Observations of past and current climate in Asia are assessed in IPCC WGI AR6 (IPCC, 2021). Examples of observed impacts in Asia with attributed CIDs are shown in Figure 10.2. Surface temperature has increased in the past century all over Asia (very high confidence). Elevation-dependent warming (i.e., the warming rate is different across elevation bands is observed in HMA) (medium confidence) (Hock et al., 2019; Krishnan et al., 2019). While there is an overall trend of decreasing glacier mass in HMA, there are some regional differences and even areas with a positive mass balance due to increased precipitation (Wester et al., 2019). Rising temperatures have resulted in an increasing trend of growing-season length. The number of hot days and warm nights continues to increase in all of Asia (high confidence), while cold days and nights are decreasing except in the southern part of Siberia (Gutiérrez et al., 2021). Large increases in temperature extremes are observed in West and Central Asia (high confidence). Temperature increase is causing strong, more frequent and longer heatwaves in South and East Asia. The 2013 East China heatwaves case is such an example (Xia et al., 2016). In 2016 and 2018, extreme warmth was observed in Asia for which an event-attribution study revealed that this would not have been possible without anthropogenic global warming (medium confidence) (Imada et al., 2018; Imada et al., 2019).

There are considerable regional differences in observed annual precipitation trend (medium confidence). Observations show a decreasing trend of the South Asian summer monsoon precipitation during the second half of the 20th century (high confidence) (Douville et al., 2021). No clear trend in precipitation is observed in high-mountain Asia (Nepal and Shrestha, 2015), while a continuous shift towards a drier condition has been observed since the early 1980s in spring over the central Himalaya (Panthi et al., 2017). Increase in heavy precipitation occurred recently in South Asia (high confidence), and in Southeast and East Asia (medium confidence) (Seneviratne et al., 2021). In Japan, there is no significant long-term trend in the annual precipitation, while significant increasing trend is observed in the annual number of events of heavy precipitation (daily precipitation ≥400 mm) and intense precipitation (hourly precipitation ≥50 mm) (JMA, 2018). Decreased precipitation and increased evapotranspiration are observed in West and Central Asia, contributing to drought conditions and decreased surface runoff.

Annual surface wind speeds have been decreasing in Asia since the 1950s (high confidence) (Ranasinghe et al., 2021). The observed changes in the frequency of sand and dust storms vary from region to region in Asia (medium confidence). The frequency and intensity of dust storms are increasing in some regions, such as West and Central Asia, due to land use and climate change (Mirzabaev et al., 2019). Significant decreasing trends of dust storms are observed in some parts of Inner Mongolia and over the Tibetan Plateau (Ranasinghe et al., 2021). In contrast, West Asia has witnessed more frequent and intensified dust storms affecting Iran and Persian Gulf countries in recent decades (medium confidence) (Nabavi et al., 2016).

There is no significant long-term trend during 1951–2017 in the numbers of tropical cyclones (TCs) with maximum winds of 66.37 km h –1 or higher forming in the western North Pacific and the South China Sea (medium confidence). There are substantial inter-decadal variations in basin-wide TC frequency and intensity in the western North Pacific (Lee et al., 2020a). Numbers of strong TCs (maximum winds of 124.93 km h –1 or higher) also show no discernible trend since 1977 when complete wind-speed data near TC centre become available (JMA, 2018). According to Cinco et al. (2016), for TCs in the Philippines there are no significant trends in the annual number of TCs during 1951–2013. Their analysis showed that the Philippines have been affected by fewer TCs above 124.93 km h –1, but affected more by extreme TCs (above 158.11 km h –1). There has been a significant northwestward shift in TC tracks since the 1980s, and a detectable poleward shift since the 1940s in the average latitude where TCs reach their peak intensity in the western North Pacific (medium confidence) (Lee et al., 2020a).

According to Bindoff et al. (2019), the oceans have warmed unabatedly since 2004, continuing the multi-decadal ocean-warming trends. Their report also summarised that there is increased agreement between coupled model simulations of anthropogenic climate change and observations of changes in ocean heat content (high confidence). Observed SLR around Asia over 1900–2018 is similar to the global mean sea level change of 1.7 mm yr –1, but for the period 1993–2018, the SLR rate increased to 3.65 mm yr –1 in the Indo-Pacific region and 3.53 m yr –1 in the Northwest Pacific, compared with the global value of 3.25 mm yr –1 (Ranasinghe et al., 2021). The extreme SLR has occurred since the 1980s along the coast of China (Feng et al., 2018b).

Ocean acidification continues with surface seawater pH values having shown a clear decrease by 0.01–0.09 from 1981–2011 along the Pacific coasts of Asia (high confidence) (Lauvset et al., 2015). For the western North Pacific along the 137°E line, the trend varies from −0.013 at 3°N to −0.021 at 30°N per decade during 1985–2017 (JMA, 2018). Ocean interior (about 150–800 m) pH also shows a decreasing trend with higher rates in the northern than the southern subtropics, which may be due to greater loading of atmospheric CO2 in the former (JMA, 2018).

Rising temperatures increase the likelihood of the threat of heatwaves across Asia, droughts in arid and semiarid areas of West, Central and South Asia, floods in monsoon regions in South, Southeast and East Asia, and glacier melting in the HKH region (high confidence) (Doblas-Reyes et al., 2021; Ranasinghe et al., 2021; Seneviratne et al., 2021). Confidence in the direction of the projected change in CIDs in Asia are summarised in Table 12.4 of WGI AR6 Chapter 12 (Ranasinghe et al., 2021).

Projections of future changes in annual mean surface air temperature in Asia are qualitatively similar to those in the previous assessments with greater warming at higher latitudes (i.e., North Asia) (high confidence) (Gutiérrez et al., 2021). Projected surface air temperature changes in the Tibetan Plateau, Central Asia and West Asia are also significant (high confidence) (Gutiérrez et al., 2021). The highest levels of warming for extremely hot days are expected to occur in West and Central Asia with increased dryness of land (high confidence) (SR1.5). Over mountainous regions, elevation-dependent warming will continue (medium confidence) (Hock et al., 2019). Glaciers will generally shrink, but rates will vary among regions (high confidence) (Wester et al., 2019). Thawing permafrost presents a problem in northern areas of Asia, particularly Siberia (Parazoo et al., 2018). Temperature rise will be strongest in winter in most regions, while it will be the strongest on summer in the northern part of West Asia and some parts of South Asia where a desert climate prevails (high confidence) (Gutiérrez et al., 2021). The wet-bulb globe temperature, which is a measure of heat stress, is likely 2 to approach critical health thresholds in West and South Asia under the RCP4.5 scenario, and in some other regions, such as East Asia, under the RCP8.5 scenario (high confidence) (Lee et al., 2021a; Seneviratne et al., 2021). The occurrence of extreme heatwaves will very likely increase in Asia. Projections show that a sizeable part of South Asia will experience heat stress conditions in the future (high confidence). It is virtually certain that cold days and nights will become fewer (Ranasinghe et al., 2021).

Projections of future annual precipitation change are qualitatively similar to those in the previous SREX and AR5 assessments (IPCC, 2021). Avery likely large percentage increase in annual precipitation is projected in South and North Asia (high confidence) (Douville et al., 2021; Lee et al., 2021a). Precipitation is projected to decrease over the northwest part of the Arabian Peninsula and increase over its southern part (medium confidence) (Gutiérrez et al., 2021). Both heavy and intense precipitation are projected to intensify and become more frequent in South, Southeast and East Asia (high confidence) (Seneviratne et al., 2021). There will be a large increase in flood frequency in these monsoon regions (Oppenheimer et al., 2019). Without further mitigation efforts, this will lead to continued loss of lives and infrastructure. SR1.5 assessed higher risk from heavy precipitation events at 2°C compared with 1.5°C of global warming in East Asia. A large ensemble-modelling study shows that future warming is expected to further increase winter precipitation, and extreme weather events, such as rain-on-snow, will result in an increase in extreme runoff in Japan (low confidence) (Ohba and Kawase, 2020). Furthermore, the earlier snowmelt will affect energy supply by hydropower.

Monsoon land precipitation likely will increase in East, Southeast and South Asia mainly due to increasing moisture convergence by elevated temperature (high confidence); however, there is low confidence in the magnitude and detailed spatial patterns of precipitation changes at the sub-regional scale in East Asia (Doblas-Reyes et al., 2021). Increasing land–sea thermal contrast and resultant lower tropospheric circulation changes, together with increasing moisture, are projected to intensify the South Asian summer monsoon precipitation (medium confidence). Anthropogenic aerosols greatly modify sub-regional precipitation changes, and their spatio-temporal changes are uncertain (Douville et al., 2021). Monsoonal winds will generally become weaker in a future warming world with different magnitudes across regions (medium confidence). Future changes in sand and dust storms are uncertain.

The global proportion of very intense TCs (category 4–5) will increase under higher levels of global warming (medium to high confidence). Mean global TC precipitation rate will increase (medium to high confidence). Models suggest a reduction in TC frequency but an increase in the proportion of very intense TCs over the western North Pacific in the future; however, some individual studies project an increase in western North Pacific TC frequency (medium confidence) (Cha et al., 2020). In the western North Pacific, some models project a poleward expansion of the latitude of maximum TC intensity, leading to a future increase in intense TC frequency south of Japan (medium confidence) (Yoshida et al., 2017).

Relative SLR associated with climate change in Asia will range from 0.3–0.5 m in SSP1-2.6 to 0.7–0.8 m in SSP5-8.5 for 2081–2100 relative to 1995–2014 (Ranasinghe et al., 2021). In coastal regions, evaluation of SLR is necessary at the regional scale to assess the impacts on coastal sectors. Liu et al. (2016c) investigated the regional-scale SLR using dynamic downscaling from the three global-climate models in the western North Pacific. In their projection in the case following the RCP8.5 scenario, the regional sea level rises along Honshu Island in Japan during 2081–2100 relative to 1981–2000 are 6–25 cm higher than the global mean SLR due to the dynamic response of the ocean circulation. For the impact assessment of coastal hazards, the total SLR included extreme events due to storm surge and high ocean waves, which are influenced by the changes in TCs (Seneviratne et al., 2021). Mori and Takemi (2016) summarised the characteristics of TCs in the western Pacific in the past and in the future, and the extreme value of significant wave height increased in several regions. There is considerable increase in the return levels along the China coast under 2.0°C warming compared with that under the 1.5°C warming scenario (Feng et al., 2018b).

Ocean acidification will continue over the 21st century (virtually certain) (SROCC). Projected decrease in global surface ocean pH from 1986–2005 to 2081–2100 is about 0.145 under RCP4.5 (Lee et al., 2021a).

Diverse and complex climate characteristics in Asia limit climate models’ ability to reasonably simulate the current climate and project its future change (Gutiérrez et al., 2021).

Energy consumption of Asia accounts for 36% of the global total at present. China, India and the ASEAN countries have largely contributed to the ever-growing global energy consumption. Asia is predicted to account for 80% of coal, 26% of natural gas and 52% of electricity consumption of the world by 2040 (IEA, 2018). The share of Asia in the global primary energy consumption will increase to 48% by 2050. China continues to be the world’s largest energy consumer, and the combined consumption of India and ASEAN will be similar to that of China by that time (IEEJ, 2018).

The current energy structure of Asia is dominated by fossil fuels. As the trend indicates, the share of coal in China’s primary energy consumption is forecasted to sharply decline from 60% in 2017 to around 35% in 2040 (BP, 2019). In contrast, India and ASEAN rely more on coal since coal may meet their soaring energy demand. Accordingly, more than 80% of the global coal will be consumed in Asia by 2050. China will surpass the USA in about 10 years to become the world’s largest oil consumer. India will then replace the USA to be the second largest by the late 2040s (IEEJ, 2018).

Around 60% of the incremental electricity demand globally, predicted to double by 2050, will occur in Asia. By that time, the electrification rate will increase to 30%, but 40% of electricity demand will be still covered by coal (IEEJ, 2018). Asia accounts for almost half of the growth in global renewable power generation. It is hardly possible for Japan and Republic of Korea to develop additional nuclear power plants as planned, whereas nuclear generation continues to increase quickly in China and the scale will be similar to the entire generation of OECD by 2040 (BP, 2019). India and Russia’s nuclear power sectors are also growing fast (e.g., the recent launch of the Akademik Lomonosov offshore nuclear power plant in Russia).

The rapid growth of energy demand in Asia reinforces the region’s position as the largest energy importer (BP, 2019). Around 80% of energy traded globally will be consumed in Asia, and the rate of self-sufficiency will decrease from 72 to 63% by 2050. This tendency is especially remarkable for ASEAN, which will become a net importer in the early 2020s. The self-sufficiency rate of coal will be maintained at a level of 80%, while that of oil and natural gas will decline significantly. The additional oil imports of the emerging Asian economies will be from North America, the Middle East and North Africa. The main players in Asia for the liquefied natural gas imports will extend from Japan and Republic of Korea to China and India. ASEAN has been a net exporter of natural gas but starts to expand its importation due to the increased consumption and resource depletion (IEEJ, 2018).

The increase in energy demand at a rapid rate in these countries thus cannot be attributed only to population growth and rising living standards, but also to increasingly extreme temperature variations. The decrease in precipitation influences energy demand as well, as countries are becoming more dependent on energy-intensive methods (e.g., desalination, underground water pumping) to supply water. Similarly, energy systems are influenced by the way the agriculture sector, mainly in Al Mashrek, relies increasingly on energy-intensive methods (e.g., more fertilisers, different irrigation and harvesting patterns) (Farajalla, 2013).

Climate change has direct and indirect impacts on energy and industrial systems. It has a particularly wide and profound impact on energy systems (energy development, transportation, supply, etc.). With global warming, the energy consumption for heating in winter decreases, while the energy consumption for cooling in summer significantly increases, but the overall energy demand shows an upwards trend (high confidence) (Sailor, 2001; Szabo et al., 2018). Such demands in summer seasons will by far exceed any energy savings from the decrease in heating demand due to warmer winters. Higher demand for cooling due to hotter temperatures has become a major challenge in the energy sector in all countries. Furthermore, decreased water levels due to lower precipitation reduces hydroelectric output. This is particularly the case for countries such as Syria and Iraq with large hydroelectric capacity (Hamid and Raouf, 2009). Additionally, the decrease in water levels negatively affects low-carbon energy systems such as concentrated solar power and thermal-generation plants that require regular cooling and cleaning.

Climate change adds extra pressure to current energy infrastructures in most countries where systems failures and blackouts are already common (Assaf, 2009). In the wake of extreme weather events (e.g., heatwaves), energy infrastructures remain inadequate to cope. This is particularly the case for countries such as Lebanon, Syria, Jordan and Palestine, with poor electricity infrastructures (Jordan, 2015). Extreme weather events could generate grave damage to power plants, most being located only a few metres above sea level, as well as power-transmission towers and lines. In Lebanon, a small country where there are no Indigenous energy resources, the disruption of shipping of fuel supplies due to extreme weather events is a major risk. Other extreme weather events, such as floods and sandstorms, expose energy and industrial systems in the coastal areas due to a rise in sea level. Countries of the Arabian Peninsula are projected to experience significant inland flooding as sea levels rise (Hamid and Raouf, 2009). In East Asia wet snow accretion enhanced by global warming often causes damage to electric power lines (Sakamoto, 2000; Ohba and Sugimoto, 2020).

Universal energy access is a big challenge for Asia (IEA, 2018). About 230 million Indian people lack access to electricity, and around 800 million still use solid fuels for cooking (Sharma, 2019). The average electricity access rate in South Asia was 74%, the equivalent of 417 million people without electricity and accounting for more than a third of the global 1.2 billion lacking the access (Shukla et al., 2017). With a total population of nearly 640 million in ASEAN, an estimated 65 million people remain without electricity and 250 million rely on solid biomass for cooking fuel (IEA, 2017). Universal access to electricity is expected to be achieved by 2030, while 1.6 billion people in Asia will still lack clean energy for cooking (UNESCAP, 2018b).

Asia faces an energy security problem even with the rapid growth in production and trade (IEEJ, 2018). Among 13 developing countries with large energy consumption in Asia, 11 are exposed to high energy security risk (WEC, 2018). This will be a major challenge for the sustainable development of Asia due to the vulnerability to global energy supplies and price volatility (Nangia, 2019). Asia lacks natural energy resources and has the smallest oil reserve but largely relies on fossil fuels. The dependency on fossil fuels was as high as 88.3% in China, 72.3% in India, 89.6% in Japan and 82.8% in Republic of Korea in 2013 (BP, 2014). Many countries in South Asia rely on a single source to supply more than half of the electricity (i.e., 67.9% from coal for India, 99.9% from hydropower for Nepal, 91.5% from natural gas for Bangladesh and 50.2% from oil for Sri Lanka) (Shukla et al., 2017). Additionally, cooperation in Asia to create the integrated energy systems needed for enhancing overall security is still at a very preliminary stage due to countries having different strategic plans and lack of cooperation among them on the common concerns (Kimura and Phoumin, 2013).

Even though energy efficiency is improving, the deployment of low-carbon energy, such as renewables, is not sufficient in Asia. To be consistent with the temperature goal of the Paris Agreement, the share of renewables in total energy consumption needs to reach 35% in Asia by 2030. Moreover, the financing to deploy renewables presents another considerable challenge (UNESCAP, 2018b).

In order to cope with climate change, renewable energy has become the core of energy development and transformation. Since the 1960s, the total solar radiation on the ground in Asia has shown a downwards trend as a whole, which is consistent with the change in global total solar radiation on the ground, and has experienced a phased change process of ‘first darkening and then brightening’ (high confidence). This conclusion has been further confirmed by ground station observations, satellite remote sensing inversion data and model simulation research (Wang and Wild, 2016; Qin et al., 2018; Yang et al., 2018a).

However, wind speed over most Asian regions is obviously decreasing (high confidence). Based on meteorological observation records or reanalysis data, many studies have analysed the variation of near-surface average wind speed in Asia. It is generally found that wind speed has declined since the 1970s, although the declining trend is different in different subregions. (Yang et al., 2012c; Lin et al., 2013; Liu et al., 2014b; Zha et al., 2016; Guo et al., 2017a; Torralba et al., 2017; Wu et al., 2017a; Ohba, 2019). The decline of near-surface wind speed in Asia is consistent with the general decline of global land-surface wind speeds, among which the frequency of strong winds and the decline of wind speed are more prominent (McVicar et al., 2012; Jiang et al., 2013; Blunden and Arndt, 2017; Wu et al., 2018c). Since the early 2010s, the average wind speed in the world and some parts of Asia has shown signs of increasing (Li et al., 2018d; Wu et al., 2018c; Zeng et al., 2019), which seems to be an inter-decadal variability. Whether this means a change in its trend needs the support of longer observation data.

At the same time, with the increase in the proportion of renewable energy in the power system, the power system will be more vulnerable to climate change and extreme weather and climate events, and the vulnerability and risk of the power system will greatly increase (medium confidence).

The overall solution would be to develop a resilient energy system and avoid the risk of unsustainable energy growth in developing Asia. This requires that strategic planning be consistent with the long-term climate projection, impact and adaptation (EUEI-PDF, 2017). Although no single policy package would be applicable for all the countries across the region, several measures could be addressed as the common options, including fortification of energy infrastructure and diversification of the sources by sufficient investment, improvement of energy efficiency for sector flexibility, and promotion of regional cooperation and integration for increasing energy security (UNESCAP, 2018b). Adaptation also includes promoting renewable energy resources, securing local natural gas resources, enhancing water production and adopting green-building technologies. These adaptation measures may help increase readiness for the anticipated impact of climate change.

The improvement of energy efficiency and demand-side management can alleviate supply constraints and thus lower overall required-energy capacity. Energy storage, smart grids for the electricity network as well as other flexible management measures enable this energy demand shifting. Regional integration of energy markets drives productivity increase, cost reduction, new investment, human capability and diversity of energy sources (WEC, 2018). For example, better interconnection of natural gas supply networks among the ASEAN countries enhances gas security in the region. The development of the long-planned regional power grid would make large-scale renewable projects more viable and aid the integration of rising shares of wind and solar power (IEA, 2017).

Providing enough investment in energy supply is a top priority to extend the connections to those without access to electricity and satisfy the soaring demand (IEA, 2017). The investment in non-fossil energies like renewables has been expanding to leverage the economic growth in China, India and Republic of Korea. According to the updated estimate of ADB, 14.7 trillion USD will be needed for the infrastructure development in the power sector of developing Asia over the 15 years from 2016 to 2030 (ADB, 2017a). The cumulative investment needs of ASEAN for energy supply and efficiency up to 2040 is estimated at 2.7 to 2.9 trillion USD (IEA, 2017). Mobilising investment to such a scale will require significant participation from the private sector and international financial institutions.

Diversifying energy sources increases energy security and thus the resilience of the whole system. The deployment of renewable energy is widely recognised as a crucial measure for enhancing energy access and diversity. There remains huge potential for renewable sources in Asia (i.e., India has massive solar power potential) (Shukla et al., 2017). Many renewable technologies (i.e., hydro- and wind power as well as solar photovoltaics) are becoming competitive, and their life-cycle costs may fall below those of coal and natural gas in the near term. Great progress has been made in enhanced geothermal systems (EGS), and in the conventional and unconventional fusion power that China is promoting. Conventional and underground pumped hydropower will level out supplies for intermittent renewable energy generation.

Substantial progress may be fulfilled by increasing the share of renewable energy in the overall energy consumption of Asia (ADB, 2017a). Access to energy, particularly in rural areas, can reduce climate vulnerability of developing Asia. Due to the high cost of extending the electricity network to rural regions, an alternative way is to develop the off-grid renewable energy systems in these areas. The distributed, instead of centralised, energy systems can increase energy access and resilience (EUEI-PDF, 2017).

Some countries in the Arabian Peninsula, such as the United Arab Emirates (UAE), are adopting an array of approaches to enhance the adaptive capacity of the energy infrastructure and diffuse the risk of climate change over a larger area (e.g., energy efficiency, demand management, storm planning for power plants). In Al Mashrek, building institutional capacity in the energy sector is a necessary first step to mainstream climate-change adaptation (CCA). Countries such as Lebanon and Jordan have already made progress in mainstreaming CCA into electricity infrastructure. In the UAE, buildings account for more than 80% of the total electricity consumption. There are currently a set of measures and regulations on building conditions and specifications that are being applied to increase energy efficiency in buildings, but the rehabilitation and upgrading of old buildings still require further efforts (Environment, 2015). In Kuwait, one adaptation measure to dust storms is through the reduction of the proportion of open-desert land from 75 to 51%, the increase in protected areas from 8 to 18% and greenbelt projects in desert areas (Kuwait, 2015). Addressing climate-change impact on energy systems in Lebanon, Jordan, Syria, Iraq and Palestine needs to simultaneously consider other interlinked challenges of population growth, rapid urbanisation, refugee influx, conflict and geopolitical location. To address these challenges and provide solutions for CCA, the promotion of multi-stakeholder partnerships is key to breaking the silo approach.

These CCA measures need to be broadened to fit the scope and depth of mitigation efforts by each country. Risk assessments and vulnerability assessments are in their early stages in the energy and industrial sectors, and are not currently based on a comprehensive plan of action. The first step is to undertake comprehensive national assessments of the risks associated with climate change based on existing studies on climate impacts and risks, and by making evidence-based decisions on adaptation actions.

Both natural and managed ecosystems, ecosystem services and livelihoods in Asia will potentially be substantially impacted by changing climate (Wu et al., 2018d). There will be increased risk for biodiversity, particularly many endemic and threatened species of fauna and flora already under environmental pressure from land-use change and other regional and global processes (Zomer et al., 2014; Rashid et al., 2015; Choi et al., 2019). Biomes shift not only serves as a signal of climate change but also provides important information for resources management and ecotone ecosystem conservation. A widespread upwards encroachment of subalpine forests would displace regionally unique alpine tundra habitats and possibly cause the loss of alpine species (Schickhoff et al., 2015). In North Asia, emissions from fires reduce forests’ ability to regulate climate. A warmer and longer growing season will increase vulnerability to fires, although fires can be attributed both to climate warming and to other human and natural influences. Recent field-based observations revealed that the forests in South Siberia are losing their ability to regenerate after fire and other landscape disturbances under a warming climate (Brazhnik et al., 2017). Data support the hypothesis of a climate-driven increase in fire frequency in boreal forests with the possible turning of boreal forests from a carbon sink to a carbon source (Ponomarev et al., 2016; Schaphoff et al., 2016; Brazhnik et al., 2017; Ponomarev et al., 2018); however, warming resulting from forest fire is partly offset by cooling in response to increased surface albedo of burned areas in a snow-on period (Chen and Loboda, 2018; Chen et al., 2018a; Jia et al., 2019; Lasslop et al., 2019).

Modelling of the interactions between climate-induced vegetation shifts, wildfire and human activities can provide keys to how people in Asia may be able to adapt to climate change (Kicklighter et al., 2014; Tian et al., 2020). Conservation and sustainable development would benefit from being tailored and modified considering the changing climatic conditions and shifting biomes, mountain belts and species ranges (Pörtner et al., 2021). Expanding the nature reserves would help species conservation; to facilitate species movements across climatic gradients, an increase in landscape connectivity can be elaborated by setting up habitat corridors between nature reserves and along elevational and other climatic gradients (Brito-Morales et al., 2018; D’Aloia et al., 2019; United Nations Climate Change Secretariat, 2019). Assisted migration of species should be considered for isolated habitats as mountain summits or where movements are constrained by poor dispersal ability. Introducing seeds of the species to new regions will help to protect them from the extinction risk caused by climate change (Mazangi et al., 2016). In Asian boreal forests, a strategy and integrated programmes should be developed for adaptation of the forests to global climate change, including sustainable forest management, firefighting infrastructure and forest fuel management, afforestation, as well as institutional, social and other measures in line with Sustainable Development Goal (SDG) 15 ‘Life on Land’ (Isaev and Korovin, 2013; Kattsov and Semenov, 2014; Bae et al., 2020). Improvements in forest habitat quality can reduce the negative impacts of climate change on biodiversity and ecosystem services (Choi et al., 2021). Adaptation options for freshwater ecosystems in Asia include increasing connectivity in river networks, expanding protected areas, restoring hydrological processes of wetlands and rivers, creating shade to lower temperatures for vulnerable species, assisted translocation and migration of species (Hassan et al., 2020; Chapter 2). Reduction of non-climate anthropogenic impacts can enhance the adaptive capacity of ecosystems (Tchebakova et al., 2016).

The vulnerabilities to disaster in coastal regions with high population densities are reported in several studies (Sajjad et al., 2018) that have assessed the vulnerabilities of coastal communities along the Chinese coast and shown that roughly 25% of the coastline, and more than 5 million residents, are in highly vulnerable coastal areas of mainland China, and these numbers are expected to double by 2100. Husnayaen et al. (2018) assessed the Semarang coast in Indonesia and showed that 20% of the total coastline (48.7 km) is very highly vulnerable. Mangroves continue to face threats due to pollution, conversion for aquaculture, agriculture, apart from climate-based threats like SLR and sea erosion (Richards and Friess, 2016; Romañach et al., 2018; Wang et al., 2018b; Friess et al., 2019). Hypersalinity, storm effects on sediment deposition, fishery development and land erosion are responsible for most of the Sunderban mangrove degradations leading to loss of livelihood (Uddin, 2014; Paul, 2017). In the Sunderbans of Asia, climate change is expected to increase river salinisation, which in turn could significantly negatively impact the valued timber species, Heritiera fomes (Dasgupta et al., 2017b). Augmented potential for honey production is also predicted, which could increase the conflict between humans and wildlife (Dasgupta et al., 2017b).

Destruction by natural hazards was found to remove the above-ground C pool, but the sediment C pool was found to be maintained (Chen et al., 2018b). In the Andaman and Nicobar Islands, the 2004 Indian Ocean tsunami severely impacted mangrove habitats at the Nicobar Islands (Nehru and Balasubramanian, 2018), although new inter-tidal habitats suitable for mangrove colonisation did develop. Mangrove species with a wide distribution and larger propagules showed high colonisation potential in the new habitats compared with other species (Nehru and Balasubramanian, 2018). Mangrove sites in Asia are predominantly minerogenic, so continued sediment supply is essential for the long-term resilience of Asia’s mangroves to SLR (Lovelock et al., 2015; Balke and Friess, 2016; Ward et al., 2016a; Ward et al., 2016b).

Primary production in the western Indian Ocean showed a reduction by 20% during the past six decades, attributed to rapid warming and ocean stratification which restricted nutrient mixing (Roxy et al., 2016). Variation in secondary-production zooplankton densities and biomass in the East Asian Marginal Seas affected the recruitment of fishes due to mismatch in spawning period and larval-feed availability during the last three climate regime shifts (CRS) in the mid-1970s, late 1980s and late 1990s, which were characterised by the North Pacific index and the Pacific Decadal Oscillation index (Kun Jung et al., 2017). In the western North Pacific, climate change has affected recruitment and the population dynamics of pelagic fishes, such as sardine and anchovy (Nakayama et al., 2018), and also shifts in the spawning ground and extension of the spawning period of the chub mackerel Scomber japonicas (Kanamori et al., 2019).

Varied responses to CRS in the China seas have been observed for small pelagic fishes (Ma et al., 2019) and cephalopods (Ichii et al., 2017). The winter and summer SSTs have shown evidence of decadal variability with abrupt changes from cold to warm in substantial association with climate indices to which coastal cephalopods in the China seas respond differentially, with some benefiting from warmer environments while others respond negatively (Pang et al., 2018). In the western and eastern North Pacific marine ecosystem, it is indicated that groundfish may suffer more than pelagic fish (Yati et al., 2020). Habitat Suitability index models using SST, chlorophyll-a, sea surface height anomaly (SSHA) and sea surface salinity (SSS), as well as fishing effort, strongly indicate that Neon flying squid is affected by interannual environmental variations and undertakes short-term migrations to suitable habitat, affecting the fisheries (Yu et al., 2015). The 2015–2016 El Niño was found to impact coral reefs of shallower regions (depth of 5–15 m) in South Andaman, India, more than those beyond 20 m (Majumdar et al., 2018). On the southeast coast of India, with bleaching largely mediated by the SST anomaly and during the recovery period, macroalgae outgrowth has been observed (2.75%) indicating impacts on the benthic community (Ranith and Kripa, 2019). In the South China Sea, the increase in SST was found to be higher than predicted in recent decades, while the pH decreased at a rate of 0.012–0.014 yr –1, more than the predicted level, due to high microbial respiratory processes releasing CO2 (Yuan et al., 2019). Simulation experiments have shown differential adaptation capacity of common species (Zheng, 2019; Yuan et al., 2019).

The UN’s (2019) report on climate action and support trends highlights that the impacts of climate change on coastal ecosystems are mainly increased risks due to flooding, inundation due to extreme events, coastal erosions, ecosystem processes and, in the case of fisheries, variations in population or stock structures due to ocean circulation pattern, habitat loss degradation and ocean acidification. Analysis of data on the occurrence of varied natural hazards from 1900 to 2019 has shown that tropical cyclones, riverine floods and droughts have increased significantly, and the impacts of these events on coastal communities are also severe and destructive. The UN’s average score for SDG Goal 14 (Life Under Water) for Asia was estimated as 46 among the scores of 40 nations, and the Ocean Health Biodiversity index was comparatively high (average 87.9); however, the indices show that more region-specific action plans are required to achieve the UN 2030 goal for Life Under Water.

Apart from the human impacts, the ecology and resource abundance of coastal waters have been found to be impacted by extreme events. During tropical cyclones ecological variations, like lowering of SST, an increase in chlorophyll-a and a decrease in oxygen (Chacko, 2019; Girishkumar et al., 2019) have been observed. Global analyses of such events have indicated that they may have an impact on the fishery directly by creating unfavourable ecological conditions and destruction of critical habitats indirectly by affecting the eggs and larvae as well as subsequent fishery recruitment (McKinnon et al., 2003; Bailey and Secor, 2016). In the South China Sea in July 2000, during a 3-day cyclone period, an estimated thirtyfold increase in surface chlorophyll-a concentration was observed (Lin et al., 2003). The estimated carbon fixation resulting from this event alone is 0.8 Mt, or 2–4% of the SCS’s annual new production (Lin et al., 2003). Since an average of 14 cyclones pass over this region annually, the contribution of cyclones to the annual new production has been estimated to be as high as 20–30% (Lin et al., 2003).

Water pollution and climate stressors have been considered major challenges to ecosystem sustainability, and now it has been shown that the combined effect these two stressors would be more damaging (Buchanan et al., 2019). For seagrass beds the pollution stress was found to increase by 2.6% (from 39.7 to 42.3%) when climate factors were added. Assuming the pollution levels remain at the 2014 levels, different scenarios including RCP2.6 and RCP8.5 were worked out for the Bohai Sea, and the results indicated amplification of the impacts on the ecosystem. Pollutants like petroleum hydrocarbons, dissolved inorganic nitrogen and soluble reactive phosphorus were the major pollution stressors (Lu et al., 2018). In the future, policies that focus strictly on pollution control should be changed and take into account the interactive effects of climate change for better forecast and management of potential ecological risks (Lu et al., 2018).

Projected changes in catch potential (in percent) by 2050 and 2100 relative to 2000 under RCP2.6 and RCP8.5, based on outputs from the dynamic bioclimate envelop model and the dynamic size-based food-web models, indicate that the marine and coastal resources of most Asian countries will be impacted with varying intensity (FAO, 2018b).

Better management of resources through projections of resource distribution, abundance and catch is required; however, lack of data (e.g., oceanographic surveys) and scientific knowledge is a constraint to this aim (Maung Saw Htoo et al., 2017). Effective forecasts of areas of resource abundance based on habitat preference have to be worked out for Asian regions.

Modelling and assessment of the vulnerability and habitat suitability of the Persian Gulf for 55 species to climate change indicated that there is a high rate of risk of local extinction in the southwest part of the Persian Gulf, off the coast of Saudi Arabia, Qatar and the United Arab Emirates (UAE). Likelihood of reduced catch was observed, and Bahrain and Iran were found to be more vulnerable to climate change (Wabnitz et al., 2018). Projected changes in fish catches can impact the supply of fish available for local consumption (i.e., food security) and exports (i.e., income generation) (Wabnitz et al., 2018). As per (UNESCAP, 2018a), over 40% of coral reefs and 60% of coastal mangroves in the Asia-Pacific region have already been lost, and approximately 80% of the region’s coral reefs are currently at risk.

Regionally, the escalation in thermal stress estimated for the different global warming scenarios is greatest for Southeast Asia and least for the Pacific Ocean (Lough et al., 2018). For the 100 reef locations examined here and given current rates of warming, the 1.5°C global warming target represents twice the thermal stress they experienced in 2016 (Lough et al., 2018).

In the Southeast Asia region threats from both warming and acidification has indicated that by 2030, 99% of reefs will be affected, and by 2050, 95% are expected to be in the highest levels of the ‘threatened’ category (Burke et al., 2011), similar to global corals (Frieler et al., 2013; Bruno and Valdivia, 2016). Modelling results indicate that even under RCP scenarios, the functional traits of coral reefs can be affected (van der Zande et al., 2020) and coral communities will mainly consist of small numbers of temperature-tolerant and fast-growing species (Kubicek et al., 2019). Increases in temperature (+3°C) and pCO2 (+400 matm) projected for this century can reduce the sperm availability for fertilisation, which along with adult population decline either due to climate change or anthropogenic impacts (Hughes et al., 2017) can affect coral reproductive success thereby reducing the recovery of populations and their adaptation potential (Albright and Mason, 2013; Hughes et al., 2018; Jamodiong et al., 2018). In the southern Persian Gulf, increased disturbance frequency and severity has caused progressive reduction in coral size, cover and population fecundity (Riegl et al., 2018), and this can lead to functional extinction. Connectivity required to avoid extinctions has increased exponentially with disturbance frequency and correlation of disturbances across the metapopulation. In the Philippines experiments have also proved that scleractinian corals, such as A. tenuis, A. millepora and F. colemani, which spawn their gametes directly into the water column, may experience limitations from sperm dilution and delays in initial sperm–egg encounters that can impact successful fertilisation (de la Cruz and Harrison, 2020).

Apart from these threats, natural hazards have also been found to affect coral reefs of Asia. The extensive and diverse coral reefs of Muscat, Oman, in the northeast Arabian Peninsula were found to have long-term effects from Cyclone Gonu, which struck the Oman coast in June 2007, more than coastal development (Coles et al., 2015).

Sandy beaches are subject to highly dynamic hydrological and geomorphological processes, giving them more natural adaptive capacity to climate hazards (Bindoff et al., 2019). Progress is being made towards models that can reliably project beach erosion under future scenarios despite the presence of multiple confounding drivers in the coastal zone (Chapter 3). Assuming minimal human intervention and projected impacts of SLR by 2100 under RCP8.5-like scenarios, 57–72% of Thai beaches (Ritphring, 2018), at least 50% loss of area on around a third of Japanese beaches (Mori, 2018) will disappear.

Marine heatwaves (MHWs) in Asia have been making changes to the structure and functioning of coastal and marine ecosystems (Kim and Han, 2017; Oliver et al., 2017; Frölicher and Laufkötter, 2018; Oliver et al., 2019; Smale et al., 2019), affecting resources like copepods (Doan et al., 2019) and coral reefs (Zhang et al., 2017c). Coral reefs of the southeast Indian Ocean have been affected by MHWs (Zhang et al., 2017c).

Simulation of RCP scenarios have shown that continued warming can drive a poleward shift in distribution of the seaweed Ecklonia cava of Japan, and under the lowest-emissions scenario (RCP2.6) most populations may not be impacted, but under the highest-emissions scenario (RCP8.5) the existing habitat may become unsuitable and it can also increase predation by herbivorous fishes (Takao et al., 2015).

The UN (2019) has identified establishment of protected areas, restoring ecosystems like mangroves and coral reefs, integrating coastal-zone management practices, sand banks and structural technologies, and implementing local monitoring networks for increasing adaptive capacity and protecting the biodiversity of the coastal ecosystem. In Asia, management of marine sites by earmarking protected areas (SDG 14) has been found to be low with only 27% of areas being protected. In India, detailed CCA guidelines for coastal protection and management has been prepared considering various environmental and social aspects (Black et al., 2017). The Ocean Health index for clean waters was also low (54.6), and the threat to the ecosystem due to the combined effects of pollution and climate change was high. Table 10.2 shows the ocean and MPAs.

Table 10.2 | Status of ocean health and mean of marine protected areas (MPA)a

(a) Data are from Sachs et al. (2018).

Conservation and restoration of mangroves were found to be effective tools for enhancing ecosystem carbon storage and an important part of Reducing Emissions from Deforestation and forest Degradation plus (REDD+) schemes and climate-change mitigation (Ahmed and Glaser, 2016). In East Asia, restoration success has been attributed to choosing the right geomorphological locations (Van Cuong et al., 2015; Balke and Friess, 2016) and co-management models (Johnson and Iizuka, 2016; Veettil et al., 2019).

In South Asia, restoration programmes have been largely successful (Jayanthi et al., 2018) but in some regions partly a failure due to inappropriate site selection, poor post-planting care and other issues (Kodikara et al., 2017). Using remote sensing it has been observed that there are high recovery rates of mangroves in a relatively short period (1.5 years) after a powerful typhoon, indicating that natural recovery and regeneration would be a more economically and ecologically viable strategy. Better mangrove management through mapping is suggested (Castillo et al., 2018; Gandhi and Jones, 2019). Statistical tools developed for modelling biomass and timber volume (Phan et al., 2019), and allometric models to estimate above-ground biomass and carbon stocks (Vinh et al., 2019), will be useful in estimating stocks in mangroves. Future mangrove loss may be offset by increasing national and international conservation initiatives that incorporate mangroves, such as the SDGs, Blue Carbon, and Payments for Ecosystem Services (Friess et al., 2019). Since seagrass meadows and marine macroalgae are important habitats capable of combating impacts of climate change, the need for a global networking system with participation of stakeholders has been suggested (Duffy et al., 2019).

Across Asia and its various sub-regions, the key drivers behind an increasingly inadequate supply of freshwater resources, affecting the livelihood security of millions, are varied, complex and intersect with multiple social, cultural, economic and environmental stressors (Luo et al., 2017; Tucker et al., 2015; Kongsager et al., 2016). Water stress has been defined as the situation ‘when the demand for water exceeds its supply, during a certain period of time, or when poor quality restricts its use’(Felberg et al., 1999; see also Figure 4.32 in Lee et al., 2021a).

Freshwater resources in Asia, which include both surface water and groundwater, are considerably strained, and changing climate is likely to act as a major stress multiplier (Dasgupta et al., 2015 ; Fant et al., 2016; Gao et al., 2018c; Mack, 2018). In Southern and Eastern Asia (SEA) nearly 200 million people are at risk of serious water-stressed conditions. Effective mitigation might reduce the additional population under threat by 30% (60 million people), but still there is a 50% chance that 100 million people across SEA might face a 50% increase in water stress and a 10% chance that water stress will almost double in the absence of wide-ranging, multi-scalar adaptive measures (Gao et al., 2018c). With Millennium Development Goal 7c, which aimed to halve the population that had no sustainable access to water and basic sanitation before 2015, not having been fully realised, and Sustainable Development Goal 6 on water and sanitation not having been effectively operationalised, the water stress is likely to increase by the end of 2030 (Weststrate et al., 2019).

In Asia and elsewhere the interplay between the challenge of sustainability and climate change poses major policy challenges (von Stechow et al., 2016). The pursuit of SDG 6—protection and restoration of water-related ecosystems, universal and equitable access to safe and affordable drinking water for all, improvement in water quality by reducing pollution, elimination of dumping and significant reduction in release of hazardous chemicals and materials, and treatment of waste water through recycling and safe reuse globally—could be directly or indirectly challenged and undermined by climate change (Parkinson et al., 2019). Dissolved organic materials from sewage can enhance CO2 emissions, especially in rapidly urbanising river systems which receive untreated waste water and/or sewage across developing countries (Kim et al., 2019b). Conversely, policy interventions aimed at significant augmentation in water-use efficiency across all sectors, ensuring sustainable withdrawals and supply of freshwater to address water scarcity and a significant reduction in the number of victims of water scarcity, especially the poor and marginalised, could mitigate vulnerabilities caused by climate change. More interdisciplinary research is needed on highly precarious future pathways and the intersection between CIDs and non-climate drivers in order to anticipate and mitigate diverging and uncertain outcomes.

According to a quantitative scenario assessment for future water supply and demand in Asia to 2050, based on global climate change and socioeconomic scenarios (Satoh et al., 2017), water demand in sectors such as irrigation, industry and households will increase by 30–40% around 2050 in comparison with 2010. Water stress is likely to be more pronounced in Pakistan, and northern parts of India and China. By mid-21st Century, the international transboundary river basins of Amu Darya, Indus, Ganges could face severe water scarcity challenges due to climatic variability and changes acting as stress multipliers (high confidence). Within a country as well, the water scarcity could be exacerbated, such as in India and China, due to various drivers like population increase and climate change. Research on the differentiated impacts of climate change on freshwater sources across the Asian sub-regions remains inconclusive and requires assessment at the sub-regional scale (IPCC, 2014b; Wester et al., 2019).

The climate-change impact on different parts of freshwater ecosystems (Section 10.4.2) has affected water supply in various sub-regions of Asia. While headwater zones are susceptible to change in snow cover, permafrost and glaciers, the downstream plain areas of these river systems are vulnerable to the increasing high demand of freshwater which will affect water availability in space and time. The observed impact of climate change has also been seen in direct physical losses such as precipitation (Mekong Delta), floods (Vietnam) and saltwater intrusion leading to low agricultural productivity (Mora et al., 2018; Almaden et al., 2019a; Pervin et al., 2020).

The HKH region extends 3,500 km from Afghanistan in the west to Myanmar in the east. It is a source of major river systems originating in Asia, supporting livelihoods, energy, agriculture and the ecosystem for 240 million people in the mountains and hills and 1.65 billion people in the plains (Sharma et al., 2019). The HKH region stores about half of the ice mass in HMA, provisioning freshwater to almost 869 million people in the Indus, Tarim, Ganges and Brahmaputra river basins. While the warming climate increases the melt-water runoff enhancing water supply, it is indeed at the cost of glacier-mass reduction that would eventually reduce melt water and impact the people’s livelihood downstream in the future (Nie et al., 2021). The melt runoff from the region plays an important role in downstream agriculture such as in the case of Indus where two-thirds of total irrigation withdrawal is from melt runoff in the pre-monsoon season (Biemans et al., 2019). Changes in cryosphere and other environmental changes have already impacted people living in high-mountain areas and are likely to introduce new challenges for water, energy and food security in the future (Borodavko et al., 2018; Adler et al., 2019; Bolch, 2019; Hoelzle et al., 2019; Rasul and Molden, 2019; Shen et al., 2020).

With climate-change impacts resulting in the shrinking and melting of snow, ice, glacier and permafrost, and correspondingly causing an increase in melt water, the incidences of flash floods, debris flow, landslides, snow avalanches, livestock diseases and other disasters in the HKH region have become more frequent and intense. Some of the key factors that get in the way of assigning confidence levels to climate-change impacts include lack of sufficient observed data on factors such as river discharges, precipitation and glacier melt (You et al., 2017). Climate-change impacts cryospheric water sources in the Hindu Kush, Karakoram and Himalayan ranges which, in turn, carry consequences for the Indus, Ganges and Brahmaputra basins.

The combined impacts of climate change and non-climate drivers on hydrological processes and water resources in transboundary rivers in diverse regions of Asia were well noted in AR5. In Central Asia, withdrawal is approximately equal to water availability, with Turkmenistan and Uzbekistan as the most water-stressed countries in the region (Karthe et al., 2017; Russell, 2018). A study on water availability in mainland South Asia has pointed in the direction of decreasing precipitation trends in recent years, which have also contributed to the increasing incidence and severity of droughts (Liu et al., 2018b). There are reports of increase in occurrence and severity of different forms of droughts in the Koshi River basin (Central Himalaya) (Wu et al., 2019a; Hamal et al., 2020; Dahal et al., 2021; Nepal et al., 2021). Figure 10.5 shows the water stress in the HKH region. The water stress is relatively higher in the western region compared with the central and eastern regions.

Climate change is also having an impact on stream flows. The changes in snowmelt water can explain 19% of the variations in rivers of arid regions like Xinjiang, China (Bai et al., 2018) (medium confidence), and the 10.6% of the runoff of the upper Brahmaputra River was contributed by snow during 2003–2014 (Chen et al., 2017c) (medium confidence). A recent study (Chen et al., 2018 f) has shown that with the average temperature after 1998 being 1.0°C higher than that during 1960–1998 in the Tienshan Mountains, the process of glacier shrinkage and decreases in snow cover are causing earlier peak runoff and aggravated extreme hydrological events, affecting regional water availability and adding to the future water crisis in Central Asia. The magnitude and frequency of flooding have increased across the Himalayan region, such as in the Tarim basin in China (Zhang et al., 2016c) and the higher Indus, Ganges and Brahmaputra, in the past six decades (Elalem and Pal, 2015). The latter also reported the highest number of flood disasters and greater spatial coverage in recent decades as compared with previous decades. In the Middle Yellow River basin, which has become much warmer and drier, climate variability accounts for 75.8% of streamflow decrease during 1980–2000, whereas during 2001–2016, change in land use and cover was the main factor in streamflow decrease, accounting for 75.5% of the decline (Bao et al., 2019). The changes in hydrological regime and extreme floods cause changes in river morphology and the river channel system which impact water availability.

In China, a quantitative assessment based on a multi-model dataset (six global hydrological models driven by three observation-based global forcings) during 1971–2010 suggested that climate variability dominated the changes in streamflow in more the 80% of river segments, while direct human impact dominated changes mostly in northern China (Liu et al., 2019b). In the Lancang-Mekong River basin, climate variability would have contributed 45% more flood occurrences in the middle of the basin, while reservoir operation reduced it by 36% during 2008–2016 as compared with 1985–2007 (Yun et al., 2020).

In western China, the total annual snow mass declines at a rate of 3.3 × 109 pg per decade (p< 0.05), which accounts for approximately 0.46% of the mean of annual snow mass (7.2 × 1011 pg). The loss could be valued in terms of replacement cost at 0.1 billion CN¥ (at the present value) every year (1 USD = 7 CN¥) compounded over the past 40 years (Wu et al., 2021). In the Mekong River Delta in Vietnam, climate-change impacts include a 30% annual increase in rainfall, shifting rainfall patterns, an average temperature increase of 0.5°C over the past 30 years and an average SLR of 3 mm yr –1 over the past three decades, resulting in a greater flooding threat (Wang et al., 2021a).

A recent study (Wang et al., 2021b) has shown that during 1936–2019, due largely to intensified precipitation induced by a warming climate, the streamflow of the Ob, Yenisei and Lena rivers has increased by ∼7.7, 7.4 and 22.0%, respectively. While rising temperatures can reduce streamflow via evapotranspiration, it can enhance groundwater discharge to rivers due to permafrost thawing. In permafrost-developed basins, the thawing permafrost will continue to result in increased streamflow. However, with further permafrost degradation in the future, the positive effect of permafrost thaw on streamflow would probably be offset by the negative effect of the increase in basin evapotranspiration. This could result in a situation where runoff reaches threshold level and then declines. This is clearly marked in the Ob River basin, which is characterised by the highest precipitation, whereas in the case of the Yenisei and Lena rivers, further research is needed.

The HKH region is susceptible to floods and related hazards caused by a cloud burst and other landscape-based processes such as glacial lake outburst floods, which can seriously damage property, lives and infrastructure (Shrestha et al., 2010). The likely increased frequency of hazards caused by abnormal glacier changes, such as the glacier collapses happened on two glaciers in western Tibetan Plateau in 2016 (Kääb et al., 2018), and also surges which were frequently found in this vast region (e.g. Bhambri et al., 2017; Mukherjee et al., 2017; Ding et al., 2018), threatening the security of the local and down streaming societies (high confidence).The total amount and area of glacier lakes increased during last decade (Zhang et al., 2015; Chen et al., 2017c) (high confidence). Himalayan rivers are frequently hit by catastrophic floods caused by the failure of glacial lakes (Cook et al., 2018; Ahluwalia et al., 2016). In Kedarnath, India (western Himalaya), a flash flood was triggered by glacier lake outburst flood (GLOF) released from the Chorabari glacial lake in June 2013 which caused extensive flooding, erosion of riverbanks and damage to downstream villages and towns, as well as the loss of several thousand lives (Rafiq et al., 2019; Das et al., 2015). Nepal has experienced 24 GLOF events which have caused considerable loss of life and damage to property and infrastructure (Icimod, 2011). There is high confidence that current glacier shrinkages have caused more glacial lakes to form in most mountainous regions, including HMA, but there is limited evidence that the frequency of GLOF has changed (Hock et al., 2019). Veh et al. (2018) reported no clear trend of increasing GLOF events in the Himalayan region, although the southern Himalaya was identified as a hotspot region compared with the western Himalaya. Research has shown a decrease in glacier area of 24% in Nepal between 1980 and 2010 (Bajracharya et al., 2014).

Climate-change impacts on both the quantity and quality of freshwater resources will hinder the attainment of SDG-6 (Water, 2020). Contamination of drinking water is caused by wildfires and drought that contribute to elevated levels of nutrients (nitrogen, phosphorus and sulphates), heavy metals (lead, mercury, cadmium and chromium), salts (chloride and fluorides), hydrocarbons, pesticides and even pharmaceuticals. Heavy rains and flooding also increase nutrients, heavy metals and pesticides, as well as turbidity and faecal pathogens in water supplies–especially when sewage treatment plants are overwhelmed by runoff (Mora et al., 2018). Pharmaceuticals and personal-care products (from source to disposal) are contributing to the vulnerability of urban waters. A study of vulnerability assessment of urban waters in highly populated cities in India and Sri Lanka, through analysing the concurrence of Pharmaceuticals and Personal Care Products (PPCPs), enteric viruses, antibiotic-resistant bacteria, metals, faecal contamination and antibiotic resistance genes (ARGs), also underlines the need for a resilience strategy and action plan (Rafiq et al., 2019).

Adequate water supply for various uses is crucial for millions of people living in the mountains of Asia. Particularly in the HKH region, mountain springs play an important role in generating stream flow for non-glaciated catchments and in maintaining dry-season flows across many watersheds (Scott et al., 2019; Stott and Huq, 2014). There is a good deal of evidence that the springs are drying up or yielding less discharge (Tambe et al., 2012; Tiwari and Joshi, 2014; Sharma et al., 2016), threatening local communities who depend on spring water for their lives and livelihoods. Some of the main reasons for drying springs include anthropogenic impacts (deforestation, exploitative land use), infrastructure (road construction), socioeconomic changes (increasing demand and modernisation of facilities) and climatic changes (changes in rainfall regime and higher temperature) (Stott and Huq, 2014; Tiwari and Joshi, 2014; Sharma et al., 2016).

The Ganges–Brahmaputra region also faces the threat increased frequency of flood events (Lutz et al., 2019). Floods and extreme events can impact river channel systems (Grainger and Conway, 2014). One of the challenges in South Asia is the shifting boundaries of river channels. For instance, the major floods on the Indus in July 2010 altered the river’s course in Pakistan, moving it closer to the Indian district of Kutch (Grainger and Conway, 2014). In the eastern tributary of the Ganges system, the alluvial fan of the Koshi River basin has shifted by more than 113 km to the west in the past two centuries (Chakraborty et al., 2010), which may be due to heavy sediment load from the Himalayan rivers in which about 50 million tons of sediment is deposited annually in the alluvial plains (Sinha et al., 2019; Chakraborty et al., 2010).

Asia is no exception to the global trend of lake ecosystems, which provide drinking water to millions of people, being degraded (Jenny et al., 2020) and severely threatened at the same time by climate change (Mischke, 2020). Lake surface conditions, such as ice cover, surface temperature, evaporation and water level react dramatically to this threat, and there are negative implications for water quantity and quality, food provisioning, recreational opportunities and transportation (Woolway et al., 2020). Due to substantial regional variability, the quantum of future changes in lake water storage remains uncertain. A recent study (Liu et al., 2019a) using Moderate Resolution Imaging Spectroradiometer 500-m spatial resolution global water product data, and applying the least squares method to analyse changes in the area of 14 lakes in Central Asia from 2001 to 2016, has shown that the area-shrinkage changes for all plains lakes in the study region could be attributed to climate change and human activities.

Asian and global water demands for irrigation, despite geographic variation in terms of water availability, are very likely to surpass supply by 2050 (Chartres, 2014). A regional quantitative assessment (Lutz et al., 2019) of the impacts of 1.5°C versus 2°C global warming for a major global climate-change hotspot–the Indus, Ganges and Brahmaputra river basins (IGB) in South Asia–shows adverse impacts of climate change on agricultural production, hydropower production and human health. A global temperature increase of 1.5°C with respect to pre-industrial levels would imply a ≈ 2.1°C temperature increase for IGB, whereas under a 2.0°C global temperature increase scenario, these river basins would warm by ≈ 2.7°C. Future warming is expected to further increase rain-on-snow events that can cause snowmelt flood during winter (Ohba and Kawase, 2020), affecting hydropower and resulting in river flooding, avalanches and landslides.

In the Mekong River Delta (in Vietnam), with an area of 40,500 km 2 and home to 17.8 million people in 2018, climate change is projected to increase the average temperature by 1.1–3.6°C, and the maximum and minimum monthly flow are projected to increase and decrease, respectively, and are likely to result in a high risk of food during the wet season and water shortages during the dry season (Wang et al., 2021a).

Researchers have found that the southern Tibetan Plateau has been consistently melting from 1998–2007 and is projected to continue melting until 2050 (Lutz et al., 2014b) (high confidence). In HMA, glacier ice is projected to decrease by 49 ± 7% and 64 ± 5% by the end of the century under RCP4.5 and RCP8.5 scenarios, respectively (Kraaijenbrink et al., 2017). Local- and regional-scale projections suggest that peak water will generally be reached around the middle of the century, followed by steadily declining glacier runoff thereafter (Hock et al., 2019). A global-scale projection suggests that a decline in glacier runoff by 2100 (RCP8.5) may reduce basin runoff by about 10% for at least 1 month of the melt season (Huss and Hock, 2018). Significantly, research on climate change and its impact across Asia remains inconclusive and requires an assessment at the sub-regional scale (IPCC, 2014a; Wester et al., 2019).

There is a projection of an increase in runoff until the 2050s mainly due to an increase in precipitation in the upper Ganges, Brahmaputra, Salween and Mekong basins, where it could be due to accelerated melting in the upper Indus basin. The runoff could increase in the range of 3–27% (7–12% in Indus, 10–27% in Ganges and 3–8% in Brahmaputra) by mid-century compared with the reference period (1998–2008) for Himalayan river basins depending on the different RCP scenarios (Lutz et al., 2014a). Likewise, Khanal et al. (2021) suggest contrasting responses to climate change for HMA rivers in which, on the seasonal scale, the earlier onset of melting causes a shift in magnitude and peak of water availability, whereas on the annual scale, total water availability increases for the headwaters. The future flow would increase in Nepal’s Central Himalaya region (Nepal, 2016; Ragettli et al., 2016; Bajracharya et al., 2018). These changes in water availability in space and time will have serious consequences in downstream water availability for various sectoral uses and ecosystem functioning in Asia (Nepal et al., 2014; Green et al., 2015; Arfanuzzaman, 2018; Wijngaard et al., 2018; Rasul and Molden, 2019); however, future water availability is largely uncertain due to significant variation in climate-change projections among different global climate models (Nepal and Shrestha, 2015; Lutz et al., 2016; Li et al., 2019a).

A recent study (Didovets et al., 2021) covering eight river catchments having diverse natural conditions within Central Asia, where water availability or scarcity is also a major developmental concern, and using the eco-hydrological model SWIM (including scenarios from five bias-corrected GCMs under RCP4.5 and RCP8.5) has show an increase in mean annual temperature in all catchments for both RCPs to the end of the 21st century. The projected changes in annual precipitation indicate a clear trend to increase in the Zhabay and decrease in the Murghab catchments, and for other catchments, they were smaller. Both the projected trends for river discharge and precipitation show an increase in the northern and decrease in the southern parts of the study region, whereas seasonal changes include a shift in the peak of river discharge up to one month, a shortening of the snow accumulation period and a reduction in discharge during the summer months.

The intensity and frequency of extreme discharges are very likely to increase towards the end of the century. The future of the upper Indus basin water availability is highly uncertain in the long term due to uncertainty surrounding precipitation projections (Lutz et al., 2016). The future hydrological extremes of the upper Indus, Ganges and Brahmaputra river basins suggest an increase in the magnitude of extremes towards the end of the 21st century by applying RCP4.5 and RCP8.5 scenarios, mainly due to an increase in precipitation extremes (Wijngaard et al., 2017). In the Brahmaputra, Ganges and Meghna, including the downstream component, the runoff is projected to increase by 16, 33 and 40%, respectively, under the climate-change scenarios by the end of the century during which the changes in runoff are larger in the wet seasons than the dry seasons (Masood et al., 2015). In the Mekong River basin also, extremely high-flow events are likely to increase in both magnitude and frequency, which can exacerbate flood risk in the basin (Hoang et al., 2016); however, uncertainty is high regarding future hydrological response due to large variation in precipitation projections, modelling approaches and bias-correction methods (Nepal and Shrestha, 2015; Lutz et al., 2016; Li et al., 2019a).

Current research on the adverse relationship between climate change and river flows suggests that there is a high possibility that some of the river basins affected by floods could be Brahmaputra, Congo, Ganges, Lena and Mekong, with a return period of 10 years (Best, 2018).

In most parts of the upper Ganges and Brahmaputra rivers, the 50-year return level flood is likely to increase and to a lesser degree in Indus River. Similarly, the extreme precipitation events are also expected to increase to a higher degree in the Indus than the Ganges and Brahmaputra basins (Wijngaard et al., 2017). Increase in extreme precipitation events is likely to cause more flash-flood events in the future (medium confidence). In the case of the Indus, increasing temperature trend in the future may lead to accelerated snow and ice melting which may increase the frequency and intensity of floods in the downstream areas (Hayat et al., 2019). The Ganges–Brahmaputra region also faces the threat of increased frequency of flood events (Lutz et al., 2019). Additionally, the Ganges basin also shows a higher sensitivity to changes in temperature and precipitation (Mishra and Lilhare, 2016).

Assessing the impact of climate change on water resources in nine alpine catchments in arid and semiarid Xinjiang of China (Li et al., 2019a), it has been noted that even though the total discharge revealed an overall increasing trend in the near future, the impact of climate change on different hydrological components indicated significant spatio-temporal heterogeneity in terms of the area, elevation and slope of catchments, which could be usefully factored into climate-adaptation strategies.

It was noted early on (Singh et al., 2011) that the main drivers that influence the provisioning of ecosystem services and human well-being in the HKH region are a mix of environmental change in general and climate change in particular, but much more data and knowledge on the HKH region are needed in order to develop either a regional or global understanding of climate-change processes.

Climate change impacts cryospheric water sources in the Hindu Kush, Karakoram and Himalayan ranges which in turn carry consequences for the Indus, Ganges and Brahmaputra basins. The impact of climate change on spring-fed rivers in the HKH is under-researched and therefore makes projections difficult. Further research is needed for understanding the impact of deforestation, urbanisation, development and introduction of water infrastructures, such as tube wells, in the hill region (Aayog, 2017). This in turn calls for greater investment in research and development for the HKH by both the national and regional organisations. There is high confidence that due to global warming, Asian countries could experience an increase in drought conditions (5–20%) by the end of this century (Prudhomme et al., 2014; Satoh et al., 2017).

Soil erosion in high-mountain areas is particularly sensitive to climate change. A recent study (Wang et al., 2020) that focused on the mid-Yarlung Tsangpo River, located in the southern part of the Tibetan Plateau, has revealed dramatic land surface environment changes due to climate change during recent decades. It has further shown that increasing precipitation and temperature would lead to increasing soil-erosion risk in ~2050 based on the Coupled Model Intercomparison Project (CMIP5) and RUSLE models.

High-resolution climate-change simulations suggest that due to deadly heatwaves projected in some of the densely populated agricultural regions of South Asia (i.e., the Ganges and Indus river basins), those regions are likely to exceed the critical threshold of wet-bulb temperature of 35°C under the business-as-usual scenario of future GHG emissions (Im et al., 2017).

In Asia and its diverse sub-regions, the challenge of adaptation to climate change at diverse sectors, sites and scales of vulnerability in the domain of freshwater resources is compounded by the nexus between long-standing non-climatic vulnerabilities and climatic impacts, both observed and projected. Water insecurities in Asia are increasing due to excessive freshwater withdrawals (Satoh et al., 2017), economic and population growth (Gleick and Iceland, 2018), urbanisation and peri-urbanisation (Roth et al., 2019), food insecurity (Demin, 2014) and lack of access to clean and safe drinking water (Cullet, 2016), which mostly affects the health of the most vulnerable members of society.

Significantly, climate change will add to already existing vulnerabilities. In the case of the Yellow River basin in China, underlining the interface between future water scarcity and hydroclimatic and anthropogenic drivers, a recent study expects moderate-to-severe water scarcity over six Yellow River sub-catchments under the RCP4.5 scenario, and anticipates that human influences on water scarcity will be worse than that of climate change, with water availability in the downstream being impacted by concurrent changes in land use and high temperature (Omer et al., 2020). Nearly 8% of internationally shared or transboundary aquifers (TBAs), ensuring livelihood security for millions of people through sustaining drinking water supply and food production, are currently overstressed due to human overexploitation (Wada and Heinrich, 2013). The Asia Pacific region has the highest annual water withdrawal due to its geographic size, growing population and irrigation practices, and water for agriculture continues to consume 80% of the region’s resources (Taniguchi et al., 2017b; Visvanathan, 2018).

In South Asia, surface water and groundwater resources are already under stress (both in terms of quality and quantity) due to population growth, economic development, poor governance and management, and poor efficiency of use in economic production. In the past 40 years, there has been an increasing reliance on groundwater in South Asia for irrigation (Rodell et al., 2009; Tiwari et al., 2009; Surie and Prasai, 2015; Bhanja et al., 2016; Shrestha et al., 2016; Mukherjee, 2018; Shah et al., 2018). It is noteworthy that India, Bangladesh, Pakistan and China together account for more than 50% of the world’s groundwater withdrawals (Scott et al., 2019). A study conducted in the Shahpur and Maner districts of Bihar, India, in which drinking water sourced from the groundwater of 388 households was tested, showed that 70–90% of the sampled household’s drinking water contained either arsenic or iron, or both (Thakur and Gupta, 2019). Given the nexus between CIDs and non-climate drivers, an effective adaptation to the impacts of climate change would also demand sustainable development and management of shared aquifer resources, which in turn require reliable TBA inventories and improved knowledge production and knowledge sharing on the shared groundwater systems (Lee et al., 2018a).

A study of peri-urban spaces involving four South Asian cities, Khulna (Bangladesh) (Pervin et al., 2020), Gurugram and Hyderabad (India), and Kathmandu (Nepal), has shown the nexus between intensifying use and deteriorating quality of water and the impact of climate change, resulting in peri-urban water insecurity and conflict (Roth et al., 2019). The challenge of ensuring access to water resources and their (re)allocation and prioritisation for marginalised communities remains on the agenda of policy-oriented interdisciplinary research and demands effective implementation of its findings at the grassroots level by the administrative agencies. Taking water security as a key CCA goal at the urban-city scale of Bangkok, a study (Babel et al., 2020) has shown the usefulness of a generic framework with 5 dimensions, 12 indicators and a set of potential variables to support national-level initiatives and plans in diverse climatic and socioeconomic conditions across various sub-regions of Asia.

In the Kathmandu valley in Nepal, where groundwater resources are under immense pressure from multiple stresses, including overextraction and climate change, mapping groundwater resilience to climate change has been demonstrated as a useful tool to understand the dynamics of groundwater systems, and thereby facilitate the development of strategies for sustainable groundwater management (Shrestha et al., 2020).

In the Mekong Delta, the groundwater storage is projected to decline by more than 120 and 160 million m 3 under RCP4.5 and RCP8.5 scenarios, respectively, by the end of the 21st century, in conjunction with land subsidence and SLR. This in turn calls for proactive planning and implementation of adaptation strategies that address multiple stresses in order to ensure sustainable utilisation of groundwater resources in the Mekong Delta in the context of future climatic conditions and associated uncertainties (Wang et al., 2021a). Proposed CCA strategies for the Mekong River basin include a better understanding of the complex linkages between climate change, technological interventions, land-use change, water-use change and socioeconomic developments both in the upstream and downstream riparian countries (Evers and Pathirana, 2018).

While South Asian countries have done well in attaining Goal 6 of Sustaining Development Goals, access to safe and clean drinking water remains a challenge. Taking Indian rivers as an example, it is suggested that participatory river protection and rehabilitation, based on comprehensive knowledge of the river-system dynamics, and local awareness at the community level, may act as a multiplier for river conservation measures (Nandi et al., 2016).

Hydroclimatic extremes in the HKH region could adversely impact the Ganga, Brahmaputra and Meghna basins (Wijngaard et al., 2017; Acharya and Prakash, 2019). Studies have recommended watershed or basin analysis to address the challenge of adaptation in urban spaces (Lele et al., 2018). A study of northern Bangladesh that focused on encouraging traditional ways of cultivation suggests that rural women have Indigenous knowledge and their participation can play a useful role (Kanak Pervez et al., 2015). The knowledge pertains to agriculture, soil conservation, fish and animal production, irrigation and water conservation. There has also been a focus on gendered construction of local flood-forecasting knowledge in rural communities in India living in the Gandak River basin (Acharya and Prakash, 2019). While designing the adaptation options, understanding the water–energy–food (WEF) nexus among different water-use sectors is crucial (Section 10.5.3). Understanding of the WEF nexus could be beneficial for achieving water security in developing countries in Asia (Nepal et al., 2019).

AR5 identified a number of adaptation challenges and options facing the stakeholders in the wake of climate-change-induced vulnerabilities, uncertainties and risks in the freshwater sector, and underlined the importance of an integrated management approach as well as acknowledging diverse socioeconomic contexts, differentiated capacities and the uneven pace of impacts. Further validated by recent research in terms of their usefulness, these adaptation options include building and improving capital-intensive physical water infrastructure such as irrigation channels, flood-control dams and water storage (Nüsser and Schmidt, 2017). Drawing upon customary institutions and combining Indigenous knowledge systems with scientific knowledge, innovative structures, including artificial glaciers, ice stupas and snow barrier bands, have been built by local communities in Ladakh, Zanskar and Himachal Pradesh in India (Hock et al., 2019; Nüsser et al., 2019). Communities in Solukhumbu, Nepal, in response to depleting water flow in snow-fed rivers, have chosen adaptation through changing practices by collecting water from distant sources for domestic consumption (McDowell et al., 2013). Taking the IPCC concept of climate risk as a basis for adaptation planning, a pilot study of flood risk in Himachal Pradesh, India (Allen et al., 2018), integrating assessment of hazard, vulnerability and exposure in the complementary domains of CCA and DRR, has identified stakeholder consultation, knowledge exchange and institutional capacity building as key steps in adaptation planning. Aquifer storage and recovery has been proposed as an ‘alternative climate-proof freshwater source’ for deltaic regions in Asia, particularly those with a history of saline groundwater aquifers (Hoque et al., 2016). It is further argued (Hadwen et al., 2015) that water, sanitation and hygiene objectives would need to be addressed as a component of a wider integrated water resource management (IWRM) framework.

Ensuring sustainability of the rivers and ecosystems requires coordinated and collaborative action on the part of all countries, with the long-term goal of synergising political, social, cultural and ecological facets associated with the riverine system. Daunting as this challenge is, evidence suggests that a long-term view of transboundary basins is not very optimistic as big rivers of Asia contribute heavily towards urban and agricultural activities, and are experiencing challenges of increasing sedimentation, large-scale damming and pollution, among others (Best, 2018). In the case of China, Sun et al. (2016) have shown that the localised vulnerabilities within the Yangtze River basin prompt an ‘integrated basin-wide approach’ that is able to account for the specific needs of each of its sub-basins.

In HMA, factors that undermine effective adaptation to climate change include both sudden-onset and slow-paced disasters along with the knowledge deficit regarding cryospheric change and its adverse impacts on water resources and also the agriculture and hydropower sectors. Other key barriers include a sectoral approach, overemphasis on structural approaches and the lack of context-sensitive, community-centric understanding of how these changes influence perceptions, options and decisions about migration, relocation and resettlement (Rasul et al., 2020; Hock et al., 2019). More interdisciplinary research is needed on highly precarious future pathways and the intersection between CIDs and non-climate drivers in order to anticipate and mitigate diverging and uncertain outcomes.

There remains a paucity of data for observed climate-change impacts on Asian agriculture and food systems since the release of IPCC AR5. Most of these impacts have been associated with drought, monsoon rain and oceanic oscillations, the frequency and severity of which have been linked with the changing climate (Heino et al., 2018; Heino et al., 2020). In general, major impacts to agricultural production, such as those observed by the farmers in the Philippines and Indonesia, include among others delays in crop harvesting, declining crop yields and quality of produce, increasing incidence of pests and diseases, stunted growth, livestock mortality and low farm income (Stevenson et al., 2013). In South Asia, the series of monsoon floods from 2005 to 2015 contributed to a high level of loss in agricultural production with peaks in 2008 and 2015 (FAO, 2018a). Similarly, in Pakistan, farmers are experiencing a decline in crop yields and increasing incidence of crop diseases as a result of climate extremes, particularly floods, droughts and heatwaves (Fahad and Wang, 2018; Ahmad et al., 2019).

Limited studies have quantified the actual impacts of climate change on agricultural productivity and the economy. In a study in the Mun River basin, northeast Thailand, yield losses of rice due to past climate trends covering the period 1984–2013 was determined to be in the range of < 50 kg ha –1 per decade or 3% of actual average yields with a high possibility of more serious yield losses in the future (Prabnakorn et al., 2018). Likewise, in China, an economic loss of 595–858 million USD for the corn and soybean sectors was computed from 2000 to 2009 (Chen et al., 2016b). On the other hand, the intensive wheat–maize system in China seems to have benefited from climate change with the northward expansion of the northern limits of maize and multi-cropping systems brought about by the rising temperatures (Li and Li, 2014).

There is high agreement in more recent studies that linked the frequency and extent of the El Niño phenomenon with global warming (Thirumalai et al., 2017; Wang et al., 2017a; Hoegh-Guldberg et al., 2018) that can trigger substantial loss in crop and fishery production. The 2004 El Niño caused the Philippines an 18% production loss during the dry season and a 32% production loss during the wet season (Cruz et al., 2017). In the 2015 El Niño event, the Indian oil sardine fishery declined by more than 50% of previous years (Kripa et al., 2018) severely impacting coastal livelihoods and economies (Shyam et al., 2017). The 2015–2016 El Niño also inflicted adverse impacts on agricultural productivity and food security, especially affecting the rural poor in middle- and lower-income countries in Southeast and South Asia (UNDP ESCAP OCHA RIMES APCC, 2017).

FAO (2001) defines food security as ‘a situation that exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life’. There is significant evidence that climate change significantly undermines both agricultural production and food security in Asia (ADB, 2017b). Increasing evidence from sub-regions and individual countries suggests that climate-related hazards, such as increasing temperature, changing rainfall, SLR, drought, flooding and the more frequent and intense occurrences of El Niño–Southern Oscillation events, all impact agricultural production with significant effects on food security. All these hazards interact with non-climatic factors, such as competing demand for scarce water resources, rural–urban migration, food prices and increasing food demand in the long term, and poor governance, among other things, that may worsen food insecurity in the region (Montesclaros and Teng, 2021).

In West Asia, particularly in Saudi Arabia and Yemen, increasing water scarcity brought about by temperature rise is anticipated to have a severe impact on agriculture and food production that undermines food security (Al-Zahrani et al., 2019; Baig et al., 2019). Saudi Arabia, for instance, was forced to phase out its wheat production starting in 2016 and fully rely on importation to conserve its drying fossil water resources (Al-Zahrani et al., 2019), a situation which is also linked to a water governance issue.

In Central Asia, a study using a bioeconomic farm model shows very large differences in climate change impacts across farming systems at the subnational level. Large-scale commercial farms in the northern regions of Kazakhstan will have positive income gains, while small-scale farms in arid zones of Tajikistan will experience a negative impact with likely effects on farm income security (Bobojonov and Aw-Hassan, 2014). Impacts on farmers’ income in western Uzbekistan will also significantly vary and could fall by as much as 25% depending on the extent of temperature increase and water-use efficiency (Bobojonov et al., 2016).

In a regional study among South Asian countries using an integrated assessment modelling framework, changes in rice and wheat productions brought about by climate change are anticipated to engender wild price volatilities in the markets (Cai et al., 2016). Price spikes are projected for 2015–2040 in all South Asian regions with India, Pakistan and Sri Lanka predicted to experience increasingly much higher rice and wheat prices than under the baseline scenario, creating major concerns about food affordability and food security. This will likely severely affect the overall economic growth of these countries since they are mainly agriculture-driven economies.

A study on mapping global patterns of drought risk projected an increase in drought frequency and intensity in the populated areas of South to Central Asia extensively used for crop and livestock production with serious repercussion to food security and potential civil conflict in the medium to long term (Carrão et al., 2016). In Southeast Asia, a Philippine study on the relationship between seasonal rainfall, agricultural production and civil conflict suggests that the projected change towards wetter rainy seasons and drier dry seasons in many parts of the country will lead to more civil conflict (Crost et al., 2018) with negative implications for food and human security. Similarly, floods and higher food prices are also associated with higher risks of social unrest in Asia that may undermine food security (Hendrix and Haggard, 2015; Ide et al., 2021).

Food insecurity will be localised across Asia where one part of the country or sub-region will be more food secured while the others, more insecure. This will require in-country or sub-regional trade and development cooperation to minimise the adverse impacts of food insecurity associated with the changing climate (Li et al., 2014a; Abid et al., 2016).

There is high confidence that agriculture will continue to be among the most vulnerable sectors in Asia in light of the changing climate (Mendelsohn, 2014; ADB, 2017b). Among the more vulnerable areas include mountain agriculture where fluctuation in crop production (Poudel and Shaw, 2016; Hussain et al., 2019), and food insufficiency, is more widespread than in lowland areas (Poudel and Shaw, 2015; Kohler and Maselli, 2009). Also vulnerable are flood-prone areas like the Vietnam Mekong River Delta where 39% of the total rice area is exposed to sustained flood risks (Wassmann et al., 2019a). Increasing temperatures and changing precipitation levels will persist to be important vulnerability drivers that will shape agricultural productivity particularly in South Asia, Southeast Asia and Central Asia as well as in selected areas of the region. With the increasing likelihood of extreme weather events, such as strong typhoons in the Philippines, the agriculture sector in the typhoon-prone areas of Southeast and East Asia, as well as the Indus Delta, will be more vulnerable to crop destruction (Mallari and Ezra, 2016). Projections on increasing SLR and flooding, such as those in Bangladesh and the Mekong Delta, will submerge and decrease crop production areas and severely affect agriculture and fishery sectors, but will also trigger outmigration from these areas (ADB, 2017b).

Vulnerability of aquaculture-related livelihoods to climate change was assessed at the global scale using the MAGICC/SCENGEN climate modelling tools, and Vietnam and Thailand were identified as most vulnerable in brackish-water aquaculture production (Handisyde et al., 2017). China, Vietnam and the Philippines are also ranked highly vulnerable in marine production. Moreover, a recent vulnerability assessment of Korean aquaculture based on predicted changes in seawater temperature and salinity according to RCP8.5 indicated that vulnerability was highest for seaweed, such as laver and sea mustard, while fish, shrimp and abalone are relatively less vulnerable as they are less sensitive to high water temperature and their farming environments are controllable to a large extent (Kim et al., 2019a). In Indonesia, farming of whiteleg shrimp (Litopenaeus vannamei) has been found to be vulnerable to increased rainfall and temperature decrease (Puspa et al., 2018).

Climate-change-induced vulnerability, however, is complicated by non-climate drivers. In Thailand, for instance, a 38% reduction (from 21,486 to 13,328 million at the present value (1 USD = 33.54 THB) in the export values of rice and products in the last quarter of 2011 has been attributed not only to the impact of tropical cyclone Nock-Ten on Thai rice export but also the economic slowdown in Thailand during 2011–2012 (Nara et al., 2014).

Considering the high vulnerability of Asia to climate change as a whole, there is a need to look at the drivers of vulnerability in an integrated and comprehensive manner. The increasing interest on nexus studies that links climate-change impacts on agriculture with the other sectors like water, energy, land-use change, urbanisation, poverty, economic liberalisation and others (see, for example, Takama et al., 2016; Aich et al., 2017; Eslamian et al., 2017; Duan et al., 2019b) could contribute to a systemwide vulnerability reduction and an important initial step towards a more climate-resilient future.

Since AR5, there has been a surge in the volume of literature that documents and assesses the different adaptation practices already employed in Asian agriculture as well as those that provide future adaptation options. There is robust evidence that a variety of adaptation practices already employed in agriculture and fisheries are valuable in reducing the negative effects of current climate anomalies but may not be sufficient to fully offset the adverse impacts of future climate scenarios. Recent literature, therefore, focuses on how to build on current adaptation initiatives and processes to improve current and future outcomes (Iizumi, 2019).

Asian farmers and fishers already employ a variety of adaptation practices to minimise the adverse impacts of climate change. In a recent systematic and comprehensive review of farmers’ adaptation practices in Asia, Shaffril et al. (2018) categorised these practices into different forms such as crop management, irrigation and water management, farm management, financial management, physical infrastructure management and social activities. ‘Climate-smart agriculture’–an integrated approach for developing agricultural strategies that address the intertwined challenges of food security and climate change–is increasingly being promoted in many parts of the region, especially in Southeast and South Asia, with potentially promising outcomes (Chandra et al., 2017; Khatri-Chhetri et al., 2017; Shirsath et al., 2017; Westermann et al., 2018; Wassmann et al., 2019b). Site-specific adaptations, such as those in Pakistan, include farmers’ utilisation of several adaptation techniques which include changing crop type and variety, and improving seed quality; fertiliser application and use of pesticides, and planting of shade trees; and water storage and farm diversification (Fahad and Wang, 2018), as well as the implementation of comprehensive climate information services for farming communities (World Meteorological Organization, 2017).

Adaptation measures are also beneficial to small-scale fishers and fish farmers (Miller et al., 2018), and through fisheries management plans (FMP) and Early warning systems, the Asian region is reducing climate impact (FAO, 2018c). The most common FMPs adopted in different Asian countries are limits to fishing gear, licensing schemes and seasonal closures (ILO, 2015), protection of nursery grounds, providing alternative livelihoods (Azad, 2017), limiting fish aggregating devices (FADs) and introduction of monitoring and control tools (Department of Fisheries (Thailand), 2015). Fishers’ strong sense of belonging to their place of residence and the sense of responsibility to protect the vulnerable fish stock has been advantageously used for developing cooperatives and starting community-based fisheries management (FAO, 2012; ILO, 2015; Shaffril et al., 2017), and these initiatives have yielded positive results.

In aquaculture, most households in shrimp communities rely on process-oriented multiple coping mechanisms such as consumption smoothing, income smoothing and migration that enhance farmers’ resilience to climate anomalies (Kais and Islam, 2018). Diversification and integration of varied resources and interventions in feed and husbandry are seen to help the aqua farmers increase their profits and overcome the impacts of climate change (Henriksson et al., 2019). Strategies like polyculture, integrated multitrophic aquaculture (IMTA) and recirculating aquaculture systems (RAS) have been suggested to increase aquaculture productivity, environmental sustainability and climate change adaptability (Ahmed et al., 2019c; Tran et al., 2020). In Bangladesh, several adaptation measures, such as integrated community-based adaptation strategies (Akber et al., 2017) and integrated coastal zone management (Ahmed and Diana, 2015), have been recommended to increase climate resilience among shrimp farmers.

More recently, nature-based solutions (NbS) have gained attention globally to enhance climate adaptation. In the context of agriculture, NbS are seen as cost-effective interventions that can increase resilience in food production while advancing climate mitigation and improving the environment (Iseman and Miralles-Wilhelm, 2021 ). Experiences in implementing NbS in agricultural landscapes have been documented both in agriculture and fisheries sectors that promote production while providing co-benefits such as environmental protection and sustainability (Miralles-Wilhelm, 2021).

Despite the numerous adaptation measures already employed, there is sufficient evidence that farmers’ current adaptation practices are inadequate to offset the worsening climate change impacts. A more comprehensive approach that integrates economic and social strategies with other measures is seen to reduce climate vulnerability. For instance, agriculture insurance is viewed as a promising adaptation approach to reduce risks and increase the financial resilience of farmers and herders in many Asian countries (Prabhakar et al., 2018; Matheswaran et al., 2019; Nguyen et al., 2019; Stringer et al., 2020). Similarly, participation of multiple stakeholders from all relevant sectors at different levels in adaptation planning and decision making is seen as an important factor in improving outcomes (Arunrat et al., 2017; Hochman et al., 2017; Chandra and McNamara, 2018). Moreover, while adaptation is local and context specific, the following general adaptation-related strategies are distilled from the current literature, based on the Asian experience, to enhance current and future adaptations (see Figure 10.7 for details or examples of each strategy):

• Create enabling policies (Chen et al., 2018d) and enhance institutional capacity (Wang et al., 2014; Hirota and Kobayashi, 2019)
• Improve adaptation planning and decision making (Xu and Grumbine, 2014; Asmiwyati et al., 2015; Dissanayake et al., 2017; Hochman et al., 2017; Qiu et al., 2018; Shuaib et al., 2018; Aryal et al., 2020b; Ruzol and Pulhin, 2021 ; Ruzol et al., 2021)
• Promote science-based adaptation measures (Alauddin and Sarker, 2014; Sapkota et al., 2015; Lim et al., 2017b)
• Adopt an integrated approach to improve adaptation (Teixeira et al., 2013; Yamane, 2014; Abid et al., 2016; Sakamoto et al., 2017; Sawamura et al., 2017; Trinh et al., 2018)
• Invest in critical infrastructure (Cai et al., 2016; Rezaei and Lashkari, 2018)
• Address farmers’ adaptation barriers (Alauddin and Sarker, 2014; Pulhin et al., 2016; Fahad and Wang, 2018; Gunathilaka et al., 2018; Almaden et al., 2019b)

  10.4.6 Cities, Settlements and Key Infrastructures

By 2050, urban areas are expected to add 2.5 billion people, 90% of whom will be in Asia and Africa (UNDESA, 2018). Critically, this urban population increase will be concentrated in India, China and Nigeria, with India and China adding 416 million and 255 million urban dwellers, respectively, between 2018 and 2050 (UNDESA, 2018).

Asia is home to 54% of the world’s urban population, and by 2050, 64% of Asia’s 3.3 billion people will be living in cities. Asia is also home to the world’s largest urban agglomerations: Tokyo (37 million inhabitants), New Delhi (29 million) and Shanghai (26 million) are the top three with Cairo, Mumbai, Beijing and Dhaka home to nearly 20 million people each (UNDESA, 2018). By 2028, New Delhi is projected to become the most populous city in the world. In certain parts of Asia (e.g., some cities in Japan and the Republic of Korea), a steep decline in urban population is projected, mainly due to declining birth rates (Hori et al., 2020). Within Asia, rates of urban­­isation differ sub-regionally. Eastern Asia has seen the most rapid urban growth with the percentage of urban population having more than tripled from 18 to 60% between 1950 and 2015, while rates of urbanisation have decreased in West Asia and remained steady in Central Asia (UNDESA, 2018).

Asian cities are seeing growing income inequality, with rural poverty being replaced by urban poverty (ADB, 2013). Regional studies show high and growing inequality within Indian and Chinese urban areas and decreasing rural–urban income gaps in Thailand and Vietnam (Baker and Gadgil, 2017; Imai and Malaeb, 2018). Critically, East Asia and the Asia–Pacific in general continue to house the world’s largest population of slum dwellers at 250 million, with most of them in China, Indonesia and the Philippines, and the highest rates of urban poverty in Papua New Guinea, Vanuatu, Indonesia and the Lao PDR (McIlreavy, 2015; Baker and Gadgil, 2017). A lot of urbanisation, especially in South Asia, is also ‘hidden’ due to poor, competing definitions of what is ‘urban’ and limited data (Ellis and Roberts, 2016).

In Asian cities, climatic hazards such as changes in precipitation and, during the Asian monsoon, SLR, cyclones, flooding, dust storms, heatwaves and permafrost thawing (Byers et al., 2018; Hoegh-Guldberg et al., 2018; Rogelj et al., 2018; Shiklomanov, 2019), as well as non-climatic vulnerabilities such as non-climatic hazards (e.g., seismic hazards), inadequate infrastructure and services, unplanned urbanisation, socioeconomic inequalities and existing adaptation deficits (Johnson et al., 2013; Araos et al., 2016; de Leon and Pittock, 2017; Meerow, 2017; Dulal, 2019) interact to shape overall urban risk (Shaw et al., 2016a; Rumbach and Shirgaokar, 2017; Dodman et al., 2019). Caught at the intersection of high exposure, socioeconomic vulnerability and low adaptive capacities, informal settlements in urban and peri-urban areas are particularly at risk (robust evidence, high agreement ) (Meerow, 2017; Rumbach and Shirgaokar, 2017; Byers et al., 2018).

There is growing empirical evidence of conditions enabling and constraining urban adaptation (Table 10.3) with relatively more literature from South, Southeast and East Asia. Governance and capacity-related deficits are repeatedly identified as significant barriers to urban adaptation (robust evidence, high agreement ) and interact with financial and informational constraints to mediate adaptation action.

Table 10.3 | Barriers and enablers to climate adaptation across Asian cities

High temperatures affect mortality and morbidity in Asia (high confidence). In addition to all-cause mortality (Dang et al., 2016; Chen et al., 2018e), deaths related to circulatory, respiratory, diabetic (Li et al., 2014b) and infectious diseases (Ingole et al., 2015), as well as infant mortality (Son et al., 2017), are increased with high temperature (high confidence). Increased hospital admissions (Giang et al., 2014; Lin et al., 2019) and ambulance transport (Onozuka and Hagihara, 2015) coincide with increased ambient temperature (high confidence). Heatwaves are particularly detrimental to all-cause and cause-specific mortality (Chen et al., 2015a; Lee et al., 2016; Guo et al., 2017b; Yin et al., 2018). Both rural and urban populations are vulnerable to heat-related mortality (Ma et al., 2015; Chen et al., 2016a; Wang et al., 2018a). Individuals with lower degrees of education and socioeconomic status, older individuals and individuals living in communities with less green space are more susceptible to heat-related mortality (high confidence) (Yang et al., 2012a; Huang et al., 2015b; Seposo et al., 2015; Son et al., 2016; Kim and Kim, 2017 ). These heat effects have been attenuating over recent decades in East Asian countries, although the driving force behind this remains unknown (high confidence) (Chung et al., 2017c; Chung et al., 2018).

Rising ambient temperature accelerates pollutant formation reactions and may modify air-pollution-related health effects (medium confidence). Higher temperatures are associated with the increased effects of ozone on mortality (Shi et al., 2020). Climate change causes intensified droughts and greater wind erosion resulting in increased intensity and frequency of sand and dust storms (Akhtar et al., 2018). Mortality and hospital admissions for circulatory and respiratory diseases are increased after exposures to Asian dust events (high confidence) (Hashizume et al., 2020). El Niño has a major influence on weather patterns in various regions. For example, it causes dry conditions that sometimes result in forest fires and transboundary haze that increased all-cause mortality in children by 41% in Malaysia (Sahani et al., 2014).

Ambient temperature is associated with the risk of an outbreak of mosquito-borne disease in South and Southeast Asia (high confidence) (Servadio et al., 2018). Warmer climates are associated with a higher incidence of malaria (Xiang et al., 2018). Moderate rainfall also promotes malaria infection, while excessive rainfall decreases the risk of malaria (Wu et al., 2017b). El Niño intensity is positively associated with malaria incidence in a single year in India (Dhiman and Sarkar, 2017). The duration and survival rate of dengue mosquito development, mosquito density, mosquito biting activity, mosquito spatio-temporal range and distribution, and mosquito flying distance are all affected by temperature (high confidence) (Li et al., 2018b). Temperature, precipitation, humidity and air pressure are major weather factors associated with dengue fever transmission (high confidence) (Sang et al., 2014; Choi et al., 2016; Xu et al., 2017).

Climate change alters the hydrological cycle by increasing the frequency of extreme weather events such as excess precipitation, storm surges, floods and droughts (high confidence). Water-borne diseases, such as diarrhoea, leptospirosis and typhoid fever, can increase in incidence following heavy rainfall, tropical cyclones and flooding events (high confidence) (Deng et al., 2015; Levy et al., 2016; Li et al., 2018b; Matsushita et al., 2018; Zhang et al., 2019b). Droughts can cause increased concentrations of pathogens, which overwhelm water-treatment plants and contaminate surface water. A positive association between ambient temperature and bacterial diarrhoea has been reported, compared with a negative association with viral diarrhoea (Carlton et al., 2016; Wang et al., 2018c).

Asia has the highest prevalence of undernourishment in the world, which was 11.4% in 2017, representing more than 515 million people. Southeast Asia has been affected by adverse climate conditions such as floods and cyclones, with impacts on food availability and prices (FAO, 2018d). Crop destruction due to tropical cyclones can include salt damage from tides blowing inland (medium confidence) (Iizumi and Ramankutty, 2015). Sea level rises result in intrusion of saline water into the coastal area of Bangladesh and people living in this area face an increased risk of hypertension resulting from high salt consumption (Scheelbeek et al., 2016).

Weather conditions have been linked to mental health. High temperatures increase the risk of mental problems including mental disorders, depression, distress and anxiety in Vietnam (Trang et al., 2016), Hong Kong SAR of China (Chan et al., 2018) and the Republic of Korea (Lee et al., 2018d). In addition, high temperatures are reported to increase the risk of mortality from suicide in Japan, the Republic of Korea, Taiwan, Province of China (Kim et al., 2016c), India (Carleton, 2017) and China (Luan et al., 2019). Extreme weather events, such as storms, floods, hurricanes and cyclones, increase injuries and mental disorders (post-traumatic stress disorder and depressive disorders) (Rataj et al., 2016), thereby negatively affecting well-being (high confidence).

Higher temperatures and increased CO2 elevate the level of allergens such as pollen, which can result in increased allergic diseases, such as asthma and allergic rhinosinusitis. The association between variations in ambient temperature and the occurrence of asthma has been reported in several Asian countries/regions such as Japan (Yamazaki et al., 2015), the Republic of Korea (Kwon et al., 2016), China (Li et al., 2016a) and Hong Kong SAR of China (medium confidence) (Lam et al., 2016).

Climate change is associated with significantly increased mortality (high confidence). Figure 10.11 shows projected health impacts due to climate change in Asia. The global estimates of excess deaths due to malnutrition, malaria, diarrhoea and heat stress will be approximately 250,000 deaths per year in 2030–2050 under the medium-to-high emissions scenario, assuming no adaptation (World Health Organization, 2014). The impacts are expected to be greatest in South, East and Southeast Asia. Another projection showed that the change in heat-related deaths is largest in Southeast Asia, which was a 12.7% increase at the end of the century under a high-emissions scenario (Gasparrini et al., 2017). As the proportion of older individuals in the population rises, the number of years lost due to disability increases more steeply (Chung et al., 2017b). In the 2080s, the number of annual temperature-related deaths is estimated to reach twice that in the 1980s in China (Li et al., 2018c). Over a 20-year period in the mid-21st century (2041–2060), the incidence of excess heat-related mortality in 51 cities in China is estimated to reach 37,800 (95% CI: 31,300–43,500) deaths per year under RCP8.5 (Bazaz et al., 2018).

Increased concentrations of fine particulate matter and ozone influenced by extreme events such as atmospheric stagnations and heatwaves are projected to result in an additional 12,100 and 8,900 deaths per year due to fine particulate matter and ozone exposure, respectively, in China in the mid-century under RCP4.5 (Hong et al., 2019a). Excess ozone-related future premature deaths is noticeable in 2030 in East Asia and India for RCP8.5 (over 95% of global excess mortality) (Silva et al., 2016).

The global estimates for increases in malaria and dengue deaths (annual estimates) are approximately 32,700 and 280 additional deaths, respectively, in 2050 under the medium-to-high emissions scenario (World Health Organization, 2014). Among these additional deaths, 9,300 and 200 deaths, respectively, are projected to occur in South Asia. The population at risk of malaria infection is estimated to increase by 134 million by 2030 in South Asia under the medium-to-high emissions scenario, considering socioeconomic development. If no actions are taken, malaria incidence in northern China is projected to increase by 69–182% by 2050 (Song et al., 2016). Another study suggested a decrease in climate suitability for malaria in northern and eastern India, southern Myanmar, southern Thailand, the Malaysia border region, Cambodia, eastern Borneo and Indonesia by 2050 (Khormi and Kumar, 2016). By contrast, climate suitability for malaria is projected to increase in the southern and southeast mainland of China and Taiwan, Province of China (Khormi and Kumar, 2016).

Dengue incidence is projected to increase to 16,000 cases per year by 2100 in Dhaka, Bangladesh, if ambient temperatures increase by 3.3°C without any adaptation measures or changes in socioeconomic conditions (Banu et al., 2014). This would represent an increase in incidence of over fortyfold compared with 2010. Higher numbers of dengue fever cases are projected to occur under RCP8.5 than RCP2.6 in China (Song et al., 2017). Compared with the average numbers in 1997–2012, the annual number of days suitable for dengue fever transmission in the 2020s, 2050s and 2080s will increase by 15, 25 and 40 d, respectively, in southern China under RCP8.5. In addition, areas in which year-round dengue fever epidemics occur will likely increase by 4500, 8800 and 20,700 km 2 in the 2020s, 2050s and 2080s, respectively, under RCP8.5 (Nahiduzzaman et al., 2015).

The global estimates for increases in deaths due to diarrhoeal disease (annual estimates) in children under 15 years in 2030 and 2050 are approximately 48,000 and 33,000 additional deaths, respectively, under the medium-to-high emissions scenario (World Health Organization, 2014). Among these additional deaths, 14,900 and 7,700 deaths, respectively, are projected to occur in South Asia. An updated projection with a pathogen-specific approach estimated 25,000 additional annual diarrhoeal deaths in Asia in 2080–2095 under the high-emissions scenario (Chua et al., 2021), while in some countries, such as Japan, net reductions in temperature-induced infectious diarrhoeal cases were estimated, because viral infections are dominant in these countries during the cold season (Onozuka et al., 2019).

South and Southeast Asia are projected to be among the highest-risk regions for reduced dietary iron intake among women of childbearing age and children under five years due to elevated CO2 concentrations (medium confidence) (Smith and Myers, 2018). The estimated number of additional deaths due to climate change in children aged under five years attributable to moderate and severe stunting in 2030 and 2050 are approximately 20,700 and 16,500, respectively, in South Asia, under the medium-to-high emissions scenario (World Health Organization, 2014). In Bangladesh, due to climate change, river salinity is projected to be increased in coastal and freshwater fishery communities leading to significant shortages of drinking water in the coastal urban areas (Dasgupta et al., 2014c).

The health co-benefits of GHG mitigation measures in energy generation have been reported to reduce disease burden. In China, the implementation of GHG policies would reduce the air-pollution-associated disease burden by 44% in 2020 under the Integrate Carbon Reduction scenario compared with the business-as-usual scenario (Liu et al., 2017b). Transition to a half-decarbonised power supply for the residential and transport sectors would prevent 55,000–69,000 deaths in 2030 compared with the business-as-usual scenario (Peng et al., 2018). A shift in travel modes from private motor vehicles to the use of mass rapid-transit lines is estimated to reduce CO2-equivalent emissions by 6% in greater Kuala Lumpur and bring important health co-benefits to the population (Kwan et al., 2017). The 25 measures developed for reducing air pollution levels in Asia and the Asia–Pacific in general would reduce CO2 emissions in 2030 by almost 20% relative to baseline projections and decrease warming by 0.3°C by 2050, which could eventually reduce heat-related excess deaths in the region (UNEP, 2019). The 25 measures include conventional emissions controls focusing on emissions that lead to the formation of fine particulate matter (PM2.5), next-stage air-quality measures for reducing emissions that lead to the formation of PM2.5 and are not yet major components of clean-air policies in many parts of the region, and measures contributing to development-priority goals with benefits for air quality. Health co-benefits outweigh mitigation costs in the Republic of Korea up to 2050 (Kim et al., 2020). Low-carbon pathways consistent with the 2°C and 1.5°C long-term climate targets defined in the Paris Agreement are associated with the largest health co-benefits when coordinated with stringent air pollution controls in Asia followed by Africa and Middle East (Rafaj et al., 2021).

Strategies to increase energy efficiency in urban environments by compact urban design and circular-economy policies can reduce GHG emissions and reap ancillary health benefits; for example, compared with conventional single-sector strategies, national CO2 emissions can be reduced by 15–36%, and the annual deaths from 25,500 to 57,500 are avoidable from air pollution reduction in 637 Chinese cities (Ramaswami et al., 2017). In a city in China, the existing mitigation policies (e.g., promotion of tertiary and high-tech industry) and the one-adaptation policy (increasing resilience) increased the co-benefits for well-being (Liu et al., 2016a).

Changing dietary patterns, particularly reducing red meat consumption and increasing fruit and vegetable consumption, contributes to reduced GHG emissions as well as reduced premature deaths. The adoption of global dietary guidelines was estimated to prevent 5.1 million deaths per year relative to the reference scenario in which the largest number of avoidable deaths occurred in East Asia and South Asia, and GHG emissions would be reduced most in East Asia (Springmann et al., 2016). In China, dietary shifts to meet national dietary reference intakes reduced the daily carbon footprint by 5–28% depending on the scenario (Song et al., 2017). In India, the optimised healthy diets (e.g., lower amounts of wheat and increased amounts of legumes) could help reduce up to 30% water use per person for irrigation and reduce diet-related GHG emissions. This would result in 6800 life-years gained per 100,000 population in 2050 (Milner et al., 2017).

Climate-change governance is characterised by a scalar/stakeholder turn which includes: (a) acknowledgement of the importance of both subnational and transnational–regional scales along with the global scale; (b) involvement of diverse stakeholders in decision-making systems; (c) reliance on bottom-up architectures of governance that are supported by the framework given by the SDGs; (d) emphasis on developmental and environmental co-benefits; (e) recognition of diverse experiences of marginalisation and social stratification, and their impacts on participation in governance-related activities; and (f) greater decentralisation and strengthening of local institutions.

In order to facilitate local adaptation, especially in a context characterised by regional diversity and spatio-temporal variation, climate-adaptive governance invites greater policy attention to institution building (formal and informal) at multiple scales and across sectors (Mubaya and Mafongoya, 2017). An incremental EbA approach underlines the advantage of drawing upon ecosystem services for reducing vulnerabilities, increasing resilience of communities to adapt to climate change, and minimising threats to social systems and human security, provided climate change remains below 2°C or, better yet, below the 1.5°C of global warming (Barkdull and Harris, 2018).

Focus on multi-level governance, both below and beyond the state level, is steadily growing (Jogesh and Dubash, 2015; Jörgensen et al., 2015; Beermann et al., 2016). Discernible diversity across political systems and sectors in Asia notwithstanding, issues relevant to multi-level climate governance includes interplay between top-down national initiatives, which stem from supranational, regional and sub-regional levels. In the case of India, national climate governance has proliferated beyond the National Action Plan on Climate Change to include State Action Plans on Climate Change of over 28 states and union territories, demonstrating graphically the shared ‘co-benefit’ in terms of creating greater space for innovation and experimentation (Jörgensen et al., 2015).

In Japan’s Climate Change Adaptation Act, enacted by the Japanese Diet in June 2018, the national government shall formulate a national action plan to promote adaptation in all sectors. This Act recommends that prefectures and municipalities designate a ‘local climate change adaptation centre’ as a local climate-change data collection and provision centre to provide more locally specific information and support for adaptation planning at the level of local municipalities. The Japanese government, in partnership with the private sector, has formulated a new comprehensive strategy, named Society 5.0, which aims at devising a number of technologically innovative solutions (Mavrodieva and Shaw, 2020).

Significantly, the co-benefit concept for international city partnerships along with comparative analysis of the challenges, capabilities and limitations of urban areas in Asia with regard to CCA governance remains under-researched (Beermann et al., 2016).

In the case of Vietnam, especially at district and community levels, where the policy capacities in hierarchical governance systems to deal with climate-change impacts are generally constrained, the value of clear legal institutions, provision of financing for implementing policies and the training opportunities for governmental staff has been well demonstrated (Phuong et al., 2018b). A key finding is that any effort to support local actors (i.e., smallholder farmers) should ensure augmentation of policy capacity through necessary investments.

In the case of China, a combination of market-based policies, emissions trading systems, a growing number of environmental non-governmental organisations (NGOs) and international networks appear to be serving as an important tool for climate governance (Ramaswami et al., 2017; Wang et al., 2017b). Public private partnership (PPP) too is receiving increasing focus, especially with regard to climate-related cost-effective and innovative infrastructure projects. In the absence of major investments in resilience, climate change may force up to 77 million people into a poverty trap by 2030 (World Bank, 2016). As seen in the case of Japan, most of the countries in Asia face the challenge of contractual allocation of risks associated with natural hazards and climate change between the public and private sectors and its long-term management in the face of uncertainty. Risk sharing, therefore, could be addressed by clear definition and allocation (World Bank, 2017). Given that in Asia, especially Singapore, China, Japan and Republic of Korea, where the water sector is a target of industrial and technology policy, PPPs could prove to be mutually beneficial. As a middle ground, key findings of a study on Indonesia (Yoseph-Paulus and Hindmarsh, 2016) underline the importance of building, sustaining and augmenting local capacity by addressing inadequacies with regard to resource endowment and capacity building, public awareness about climate change, government–community partnerships, vulnerability assessment and providing inclusive decision-making spaces to Indigenous knowledge systems and communities.

In the agriculture sector, farmers in Asia are adapting to climate change at the grassroots level (Tripathi and Mishra, 2017). A recent, comprehensive and systematic review (Shaffril et al., 2018) shows how farmers in diverse sub-regions of Asia have adopted diverse adaptation strategies through management of crops, irrigation and water, farms, finances, physical infrastructure and social activities. Much more qualitative research on farmers’ perceptions and decision-making processes about adaptation practices is needed in order to capture their location-specific priorities and get a diverse understanding of the risks and threats. A study of Vietnamese smallholder farmers’ perceptions of their current and future capacity to adapt to climate change (Phuong et al., 2018a) found considerable differences between farmers in crop production and livestock production in terms of their motives behind adopting particular planned adaptation options.

A study on farmers’ awareness of, and adaptation to, climate change in the dry zones of Myanmar, critically dependent on agriculture, indicates how those at the front line of the adverse effects of climate change are steadily abandoning the common sesame/groundnut cropping pattern, and trying to adapt to risks and uncertainties with the aid of conventional agricultural practices such as rainwater collection, water-harvesting techniques and even traditional weather forecasting techniques for weather prediction. Similarly, a case study of the Gandak basin in Nepal showed that incorporation of local knowledge into agricultural practices and weather warning systems works best when coupled with multiple sources of information based on a method of triangulation. This also intersects with gender outcomes, where women frequently receive information from the men of their households rather than directly from state institutional sources (Acharya and Prakash, 2019). Climate-change adaptive governance is facilitated by improved cross-scalar and cross-sectoral cooperation, exchange of information and experiences, and best practices (Smith et al., 2014; Watts et al., 2015; Gamble et al., 2016; Gilfillan et al., 2017).

An integrated approach informed by science, which examines multiple stressors along with Indigenous knowledge, appears to be of immense value (Elum et al., 2017). A study on Pakistan concluded that poor agricultural communities are among the worst victims of climate change (Ali and Erenstein, 2017) and that farmers who are younger, better educated, belong to joint families and possess more landholdings are likely to adapt sooner and better. Correspondingly, this category achieved higher levels of income and food security. The climate-development nexus suggests that CCA practices at the farm level can have significant development outcomes, besides reducing risk posed by changing weather patterns. Central to the CCA process is the growing recognition of the role that institutions play in both the hierarchical setting and across different scales to influence implementation of CCA in diverse areas of governance across social and political domains. Cuevas (2018) highlights the usefulness of mainstreaming CCA into local land-use planning in Albay, the Philippines, by involving networks of interacting institutions and institutional arrangements for overcoming obstacles that are potentially counterproductive and conflictual.

As noted by AR5 (IPCC, 2014a), research on issues related to both climate-change impacts on livestock production–demand for which is expected to double by 2050 in a world of 10 billion people–and policy choices with regard to adaptation, especially at the local scale, is still limited but progressing (Rojas-Downing et al., 2017). The promise of diversification of livestock animals (within species), crop diversification and transition to mixed crop–livestock systems needs to be further explored. A study of livestock farmers in Pakistan showed that risk-coping mechanisms, such as purchasing livestock insurance and increasing land areas for fodder, are far more rewarding policy options in comparison with selling livestock and migrating to another place. Relatedly, the association of migration with adaptation measures is context specific and involves a number of factors pertaining to the socioeconomic circumstances of vulnerable agricultural groups in countries like India and Bangladesh (Ojha et al., 2014). In the 2010 United Nations Framework Convention on Climate Change’s Cancun Adaptation Framework, migration was recognised as a form of adaptation that should be included in a country’s long-term adaptation planning where appropriate (Paragraph 14 f).

Furthermore, agricultural climate-adaptation policy targeting livestock farmers in rural areas is very likely to benefit from better education and awareness as well as increased access to extension services among livestock farmers on climate risk-coping choices and strategies (Rahut and Ali, 2018). In Myanmar, the lack of adequate agricultural extension strategies has had a negative impact on adaptation outcomes in what is labelled the ‘central dry zone’. Farmers’ perceptions of climate change contribute to a comprehensive understanding of the context where they identify deforestation and related activities as the main culprits. Their adaptive methods include agricultural land preparation and crop rotation practices in addition to rainwater-harvesting techniques (Swe et al., 2015). A study of vulnerable areas in Bangladesh (Alam et al., 2017) has shown that with policy support, livestock rearing can prove to be a viable substitute for crop production in areas prone to riverbank erosion. Carefully developed partnerships between government organisations and NGOs can come to the rescue of poor farmers and their precarious households by providing information about best practices for local adaptation strategies, including credit options with various institutions and creating an enabling environment for the promotion of agro-based industries. A study in community forestry in the Indian Himalayan region (Gupta and Koontz, 2019) has shown how the synergies and successful partnerships could evolve between government and NGOs in local forest governance, with the former providing technical and financial support, and the latter directing the communities to those resources, and in the making up for each other’s limitations thereby enabling and augmenting community efforts in forest governance.

A study of Pakistan (Ali and Erenstein, 2017) shows that factors such as enhanced awareness about various climate risk-coping strategies, better education and agricultural extension services, augmenting farm-household assets, lowering the cost of adaptation, improving access to services and alternative livelihoods, and providing support to poorer households appear to have paid rich dividends. Countries such as Bhutan and Sri Lanka have included provisions for ‘climate-smart agriculture’ in their nationally determined contributions (NDCs) (Amjath-Babu et al., 2019).

In the domain of forest adaptive governance, ever since the introduction of Reducing Emissions from Deforestation and forest Degradation plus (REDD+) at COP 13 in 2007 in Bali, the Indonesian experience suggests that some of the major challenges include curbing emissions, changes in cross-sectoral land-use as well as practice within forestry and lack of effective, efficient and equitable implementation of diverse forest governance practices. The issue of how forest governance institutions are conceived and managed, both at national and subnational levels, involving state, private sector and civil society, also needs serious attention (Agung et al., 2014).

In an example from Nepal, Clement (2018) showed that deliberative governance mechanisms can create the space for alternative framings of climate change to take a hold in ways that are cognisant of both the local and global contexts; this moves beyond a dependence on techno-managerialism in the construction of solutions, where local governance solutions can support institutional changes. The possibilities more incorporating deliberative methods into wider governance architecture are also expanded through an acknowledgment of the role of social learning; this is observable in the multi-stakeholder involvement that this approach fosters in regions of South Asia such as the Brahmaputra River basin (Varma and Hazarika, 2018). Additionally, recent studies have reconfirmed the importance of linking Indigenous knowledge with the scientific knowledge of climate change in diverse regions of the globe, including Asia and Africa (Hiwasaki et al., 2014; Etchart, 2017; Taremwa et al., 2017; Vadigi, 2017; Apraku et al., 2018; Inaotombi and Mahanta, 2018; Makondo and Thomas, 2018) for building farmers’ resilience, enhancing CCA, ensuring cross-cultural communication, promoting local skills, drawing upon Indigenous Peoples’ intuitive thinking processes and geographic knowledge of remote areas.

A study of the Sylhet Division in Bangladesh, deploying a knowledge quality assessment tool, found significant correlation between a narrow technocratic problem framing, divorced from traditional knowledge strongly rooted in local sociocultural histories and relatively low project success due to skewed risk-based calculations disconnected from the ground realities (Haque et al., 2017; Wani and Ariana, 2018). Highlighting the vulnerability of the Bajo tribal communities, who inhabit the coastal areas of Indonesia, to climate change, the study showed how they share several examples of their Indigenous knowledge and traditions of marine resource conservation, and how this wisdom, a valuable asset for climate adaptation governance, has been passed from generation to generation through oral tradition.

One of the major knowledge gaps in the domain of climate adaptation governance relates to implementation by various stakeholders at multiple scales, and sharing of information and experiences in this regard. There is a need to assuage the perceptions of distrust in global information, through governance methods that engage multiple stakeholders in open and lucid channels of communication (Stott and Huq, 2014). This is observable in the structure of the New Urban Agenda which formed part of the SDGs pertaining to cities and has been shaped by a bottom-up process marked by diverse participation including communities, experts and activists, rather than the top-down variant that is observable in the Millenium Development Goals (Barnett and Parnell, 2016). This approach could also be evidenced in the Paris Agreement, which placed the onus of a successful global governance regime on the development of efficient systems of regional governance. However, these emerging systems of regional governance could equally pose a challenge to the global governance in a way that can be witnessed through the development of financial groups such as the BRICS (associated economies of Brazil, Russia, India, China and South Africa) and Asian Infrastructure Investment Bank, which resulted from a perception of inadequate institutional transformation at the global level. From another perspective, a comprehensive approach would require simultaneous implementation of both bottom-up and top-down models of governance, retaining flexibility of scale.

Given the concerns surrounding food security, especially in light of the principles of common but differentiated responsibilities, under the NDCs submitted by South Asian nations under the Paris Agreement, emission reduction commitments are less likely to include the agriculture sector. Prospects for enhancing both adaptive capacity and food security could be improved by strengthening resilience and profitability through the introduction of a basket of policy choices and actions including structural reforms, agriculture value-chain interventions and landscape-level efforts for climate resilience. Correspondingly, the substantial adaptation finance gap could be closed with the help of both private finance (autonomous adaptation) and international financial transfers (Amjath-Babu et al., 2019).

For nearly five decades, integrated coastal management (ICM), advocated by several international organisations (e.g., IMO, UNEP, WHO, FAO) and adopted by over 100 countries, has been acknowledged as a holistic coastal governance approach aimed at achieving coastal sustainability and reducing the vulnerability of coastal communities in the face of multiple environmental impacts (high confidence). In view of threats posed to coastal ecological integrity by climate-change-induced tropical storm activity, accelerated SLR and littoral erosion and social–ecological impacts on the livelihood security of vulnerable coastal communities, the pressing need for approaches that innovatively combine coastal zone management and CCA measures is widely acknowledged (Rosendo et al., 2018) yet under researched. A study focusing on the three coastal cities of Xiamen, Quanzhou and Dongying, in China, a country with nearly 12% of its national coastline already covered under the ICM governance framework, suggests that whereas the ICM approach has been found to be effective in promoting the overall sustainability of China’s coastal cities (Ye et al., 2015) using accurate and reliable data, in addition, the developing unified standards could usefully reveal changing conditions and parameters related to ICM performance.

Steadily the regional scale of climate adaptive governance is acquiring salience in diverse sub-regions of Asia, and more policy-oriented empirical research is needed on how various regional forums, agencies and multilateral organisations could further contribute by way of in-house expertise and other resources, including financial. A study of climate adaptation in the health sector in Southeast Asia (Gilfillan, 2018) highlights the growing role of the Asian Development Bank (ADB) and the Asia-Pacific Regional Forum on Health and Environment, and shows that their mandates and goals could mutually benefit from the institutionalisation of coordination mechanism. An example from the Maldives shows that the 2014 Tsunami, climate change and the risk of extreme weather events have led to the legitimisation of state-led population resettlement programmes. In China, this has occurred through the renaming of previously existing resettlement initiatives as climate adaptation initiatives; however, the efficacy of resettlement as a CCA measure requires further scrutiny (Arnall, 2019). In India, the National Adaptation Fund on Climate Change has been instituted in order to enable states to implement adaptation programmes; however, this does not address the question of mainstreaming CCA into designs for development (Prasad and Sud, 2019). This is closely related to the development of National Adaptation Programmes of Action (NAPAs) where the mainstreaming of adaptation within countries has been an important concern. Insights from developing countries indicate that there is still much ground to cover. The NAPA of the Maldives prioritises food security, coastal resources and public health, while Nepal has prioritised ecosystem management and public health, and food security, among other concerns (Saito, 2013). Importantly, Bangladesh’s NAPA has shown that there is potential for ‘reflexivity’ in the integration of adaptation objectives with sectoral objectives (Vij et al., 2018). Conspicuous by their absence are the transboundary-scale adaptation policies in South Asia (Vij et al., 2017).

A distinguishing feature of the case of Japanese apple growers is the co-existence of both top-down and bottom-up adaptation practices. The former pertains to farmers who rely on the support of the cooperative for agricultural support and follow institutional mechanisms. The latter pertains to non-co-op farmers who have been responsible for innovative practices of cultivation such as the shift to peaches and the sale in the market of apples without leaf-picking. Importantly, the non-co-op group also have access to sales channels that may not be accessible to the former owing to their direct interactions with customers, among other factors (Fujisawa and Kobayashi, 2011; Fujisawa et al., 2015). The significance of this combination of top-down and bottom-up approaches to agricultural adaptation practices may be further sharpened by formulating approaches for Asia and the Pacific region in ways that contribute to the fortification of food security objectives and the idea of co-benefits. This may be carried out by enhancing the ability of farmers to better manage cultivation practices in the context of climatic variability (FAO, 2018d).

There exist numerous barriers to the mainstreaming of CCA measures across Asia. The integration of CCA into the dissemination of localised climatic information and its uptake and implementation through institutional policy arrangements remain areas of concern (Cuevas, 2018). Institutional incentives to agricultural production, for instance, are frequently compounded by the negative impacts they have on existing bases of natural resources. The disconnected operations of local governmental agencies coupled with inadequacies of cross-sectoral coordination further highlights the prevalent food–water–energy nexus (Rasul, 2016). One possible way of addressing these intersecting sources’ complexity is by locating emerging CCA measures in educational development. The introduction of CCA thinking into land-use planning in the Philippines is an example of the successful role of enhancing public education and awareness through the dissemination of information by institutional channels. The linkages between the strength of local leadership and the inclusion of CCA in localised planning activities are also well illustrated by the case study of Cuevas (2018).

As shown in the case of Pakistan, level of education shares a positive relationship with the implementation of adaptation measures (Ali and Erenstein, 2017). However, a closer examination of the educational imperatives that drive CCA in ways that improve the representational architecture of adaptation actions through a focus on gender is needed. Mainstreaming of gender into CCA would involve addressing a host of barriers to education and involvement that are often rooted in the differential structures of households, social norms and roles, and the domestic division of labour (Rao et al., 2019). A study from the Indian state of Bihar shows that gender plays a major role in determining intra-household decision making and also inhibits the ability of female-headed households to establish access to agricultural extension services (Mehar et al., 2016). Even within wider female farmer-operated federations, such as the Bangladesh Kishani Sabha (BKS), the barriers to participation stem from social factors that include the limitation of female mobility through the gendered division of labour and a lack of recognition of female agency (Routledge, 2015). Gendered inequalities in educational attainment and outcomes viewed through the lens of social vulnerability thus intersect with environmental vulnerabilities in ways that affect the ability of women to participate in CCA, owing also to a lack of access to health and sanitation facilities. These factors have a direct impact on the ability of adaptation to be effective in the global South, and are especially important in the context of the commitments of the UN Convention on the Elimination of All Forms of Discrimination Against Women countries to the objective of gender equality (Roy, 2018).

Much like any other field, CCA is greatly facilitated by science, technology and continuous innovation. These range from the application of existing science, to the development of new scientific tools and methods, to the utilisation of Indigenous knowledge and citizen science. Many of the pressing problems in Asia, including water scarcity, rapid urbanisation, loss of natural habitats, biodiversity, rising coastal and river basin hazards, and agricultural loss can be effectively minimised through the adoption of suitable scientific and technological methods. Despite the current challenges in the region, many significant advances in science and technology have been made, and the future prospects look bright. The following sections outline the present status and future prospects of science and technology in scaling up adaptation actions in four key sectors, namely (a) DRR, (b) urbanisation, (c) water and agriculture, and (d) forests and biodiversity.

With rapid advances of technologies, the use of appropriate technologies generates some degree of management problems. To resolve such problems, the enhancement of information science is essential to understand design, implementation and adoption of digital tools under crisis (Xie et al., 2020). For example, social media research reveals a way of controlling malicious information (Tanaka et al., 2014), and its characteristics under COVID-19–showing a plain text message–can be more powerful in the context of citizen engagement than media-rich communications (Chen et al., 2020b). Information behaviour needs more investigation to understand how people survive and connect in the era of information overload (Pan et al., 2020). Moreover, a new set of data (e.g., travel history record, personal health data, etc.) becomes an important base of DRR (Xie et al., 2020). Analysis of these personal data requires careful consideration, as it generates ethical issues (Sakurai and Chughtai, 2020). Indicators or measurements of technology-enabled crisis response needs to be developed for further risk reduction (Akbari and Kolokotsa, 2016; Wong et al., 2020). On the other hand, adopting infrastructure technologies requires investment, and due to the inherent uncertainties of climate projections, the future payoffs of these investments are also somewhat uncertain (Ginbo et al., 2020). In the water and infrastructure sectors, for example, various options exist for conducting cost–benefit analysis considering future uncertainty (i.e., so-called robust approaches, which are able to identify adaptation projects and infrastructure that can achieve their intended purpose(s) across a wide range of climate scenarios) (Dittrich et al., 2016). Despite substantial investment and progress in research, development and capacity building in the recent past, the majority of the developing countries in Asia are struggling to manage both water resources and the agriculture sector. Considering the frequent extreme weather conditions, progress in management tasks has become even more mammoth and, hence, we need a holistic solution, which is currently missing in field implementation. This solution should be based on advanced science and technology in association with other attributes like social, economic and political dynamics, which play a pivotal role in sustainable management of water resources and agriculture, as a way forward.

Understanding the motivations and processes underpinning decisions to adapt or not is key to enabling adaptation (see Section 17.2.2.1; Clayton et al., 2015; de Coninck et al., 2018; Taylor, 2019; van Valkengoed and Steg, 2019a; van Valkengoed and Steg, 2019b), because how and why certain people adapt is shaped by sociocultural factors, ways of making sense of risks and uncertainty, and personal motivations to undertake action (Nguyen et al., 2016; Mortreux and Barnett, 2017; Singh et al., 2018b; van Valkengoed and Steg, 2019b). The IPCC’s Assessment Report 5 was critiqued for silences on how perceptions shape climate action and the behavioural drivers of adaptation responses (Lorenzoni and Whitmarsh, 2014). Addressing this gap and assessing the growing literature from social sciences, notably psychology, behavioural economics and risk perception studies, the IPCC Special Report on 1.5°C (de Coninck et al., 2018) comprehensively assessed behavioural dimensions of CCA for the first time; however, compared with studies on mitigation behaviour, the literature on what motivates adaptation remains incomplete (Lorenzoni and Whitmarsh, 2014; Clayton et al., 2015).

There are three key aspects of adaptation to which psychology and behavioural science contribute: understanding perceptions of climate risk, identifying the behavioural drivers of adaptation actions and analysing the impacts of climate change on human well-being (Clayton et al., 2015). Overall, there is growing acknowledgement that individual adaptation is significantly shaped by perceptions of risk, perceived self-efficacy (i.e., beliefs about which options are effective and one’s ability to implement specific adaptation interventions), sociocultural norms and beliefs within which adaptation decisions are taken, past experiences of risk management and the nature of the intervention itself (Grothmann and Patt, 2005; Werg et al., 2013; Clayton et al., 2015; Truelove et al., 2015; Pyhälä et al., 2016; Deng et al., 2017; Sullivan-Wiley and Short Gianotti, 2017; Taylor, 2019; van Valkengoed and Steg, 2019a). This is in addition to more commonly understood factors shaping adaptation behaviour such as technical know-how and the cost and benefits associated with an option.

Across Asia, behavioural aspects of adaptation have been studied to a lesser extent: a global meta-analysis of 106 studies found that most research focused on North America and Europe with only 12% of papers from Asia (van Valkengoed and Steg, 2019a). Within Asia, behavioural drivers of adaptation decision making have been studied primarily in agriculture (in South, East and Southeast Asia) and disaster risk management (from Southeast and East Asia) (Table 10.4) and tend to focus on technical adaptation interventions rather than how and why people adapt (Sun and Han, 2018).

Table 10.4 | Sectors and sub-regions where behavioural aspects of adaptation have been assessed

(a) No evidence

In agriculture, studies demonstrate how perceptions of risk (e.g., climate variability) (Singh et al., 2016; Zheng and Dallimer, 2016; Burnham and Ma, 2017; Feng et al., 2017), sociocultural norms and personal experiences (Masud, 2016; Nguyen et al., 2016; Singh et al., 2016), and perceived efficacy of adaptation interventions in having a positive and desirable impact (Halbrendt et al., 2014; Truelove et al., 2015; Feng et al., 2017), affect adaptation decisions. Policies on providing early warnings of drought or information on prevention techniques shape farmer decisions to undertake adaptation interventions (Wang et al., 2015).

In disaster risk management, risk appraisal (Samaddar et al., 2014; Rauf et al., 2017; Hung et al., 2018), previous experience and losses (Said et al., 2015; Hung et al., 2018; Walch, 2018)12, 11 perceived probabilities and consequences (Reynaud et al., 2013), perceived self-efficacy (Ung et al., 2015; Hung et al., 2018) and awareness (Hung et al., 2018; Wu et al., 2018a; Alvi and Khayyam, 2020) shape preparedness. Individual risk management is nested within public policies, such as those on flood management, which shape individual flood risk perception and protective behaviours (Reynaud et al., 2013) as well as personal factors such as religious beliefs (Alshehri et al., 2013). For example, communities often perceive disasters as ‘acts of God’ (Birkmann et al., 2019) or punishment for wrongdoings (Alshehri et al., 2013; Iqbal et al., 2018), which might constrain adaptive action. However, religious faith can also motivate people to prepare for extreme events, as Alshehri et al. (2013) showed in Saudi Arabia demonstrating how ‘Islam urges that it is most important to prepare the people to escape from disaster’ (p.1825).

Trust in public action as a mediator of risk management has had conflicting evidence: some studies have discussed trust as being critical to effective preparedness (Kittipongvises and Mino, 2015; Walch, 2018), while others have found that trust in public actions, such as structural interventions to mitigate flood impacts, can lower individual motivations to act since they feel protected (Hung et al., 2018).

Belief in climate variability and change significantly shapes adaptation decision making (Le Dang et al., 2014; Singh et al., 2016; Khanal et al., 2018; Liu et al., 2018a) with those believing in climate change and associated impacts tending to engage in adaptation. Crucially, those who do not believe in climate change can be influenced by social norms (Arunrat et al., 2017) thereby incentivising adaptation behaviour. While risk perception is a critical step in adaptation decision making, higher risk perception does not necessarily signal better capacity to cope: in Taiwan, Province of China, Sun and Han (2018) highlight how perceptions of climate risk as a global problem tends reduce its urgency as an individual issue. Providing information on climate risks, impacts and possible adaptation options enables adaptation behaviour (Piya et al., 2013; Zheng and Dallimer, 2016; Rauf et al., 2017), but information alone is not sufficient to motivate adaptive behaviour. Specifically, awareness building on concrete measures and outcomes, such as the amount of water saved or number of deaths averted, rather than abstract notions of climate change, motivate adaptation (Deng et al., 2017; Rauf et al., 2017).

Changes in current lifestyles and consumption patterns are acknowledged as critical to climate action (de Coninck et al., 2018; IGES, 2019). With rapidly changing diets and increasing purchasing power, lifestyle changes in countries across Asia, especially those with large populations such as China and India, will be critical to contributing to global climate solutions (IGES, 2019). Lifestyle shifts that can contribute towards adaptation include:

• Engaging in urban agriculture through rooftop gardening, community gardens in urban and peri-urban areas and so forth (with implications for food-associated footprints but also nutritional, livelihood and well-being benefits) (Mohanty et al., 2012; Ackerman et al., 2014; Padgham and Dietrich, 2015)
• Shifts towards organic farming and creating demand for organically sourced food and other materials
• Shifts towards water-saving behaviour such as rainwater harvesting, water conservation, reducing water usage and so forth

Overall, understanding behavioural factors shaping adaptation implementation and uptake is important (medium evidence, high agreement ). While there is a growing literature on behavioural drivers of adaptation at the individual and household levels, gaps remain in understanding how socio-cognitive factors affect adaptation behaviour at higher scales (e.g., at local or subnational government, in the private sector, etc.)13. 12 More empirical evidence is needed in sectors beyond agriculture and disaster risk management (e.g., factors motivating urban adaptation) and better coverage across Asia’s sub-regions. Importantly, there are no studies on the behavioural aspects of adaptation from Central Asia.

Estimates of adaptation costs and financial needs have evolved significantly since the previous IPCC assessments. These developments are based on improvements in the understanding of how the hazard interacts with the physical and socioeconomic elements, and how to capture these interactions in systematic modelling frameworks. The developments are also clearly reported especially in the area of addressing the underestimates in adaptation costs that the previous studies suffered from as the previous studies tended to rely on data from wealthy economies (Hochrainer-Stigler et al., 2014; Carleton et al., 2020). The adaptation cost estimates have also improved since the previous IPCC reports due to constant improvements in capturing the loss and damages of disaster events (Hochrainer-Stigler et al., 2014). The reliance of earlier studies on correlations to derive adaptation costs was addressed to some extent by addressing the endogeneity of disaster measures (Kousky, 2014), especially by relying upon the physical measures of disasters such as wind speed, although more work is needed in this area.

Climate change can cause significant impacts and as a result can impose considerable adaptation costs on countries and people. Despite the importance, the research on adaptation costs is limited in Asia, especially on the economy-wide costs, while fragmented literature is available on sector-level adaptation costs. Most of the available literature on adaptation costs at the regional level originate from the work carried out by development finance institutions such as ADB.

Estimates suggest that climate-change impacts could result in a loss of 2% of the GDP of South Asian countries by 2050 and 9% by 2100 (Ahmed and Suphachalasai, 2014). These impacts will be felt in major vulnerable sectors, including agriculture, water, coastal, marine, health and energy, and will have significant impact on the economic growth and poverty reduction in the region. Countries could differ widely in terms of the economic costs they face. In South Asia, the economic costs were projected to be 12.6% of the GDP for the Maldives, which is the highest among the South Asian countries, and 6.6% for Sri Lanka, the least among the South Asian countries. The resultant adaptation costs for countries were projected to range from 0.36% (Copenhagen Cancun Scenario for 2050) to 1.32% (business-as-usual scenario) of the GDP in various scenarios during 2010–2050 (Medium agreement , limited evidence) (Ahmed and Suphachalasai, 2014).

Arto et al. (2019) have reported the adaptation costs of the Mahanadi Delta in India for agriculture, fisheries and infrastructure sectors (Arto et al., 2019). The cumulative adaptation costs for 2015–2016 were reported to be 276 million USD for agriculture and 0.163 million USD for fisheries. In comparison, the modelled cumulative agricultural GDP loss due to climate-change impacts was reported to be 5% up to 2050, and 8% for infrastructure. Adaptation interventions, such as embankments, were found to provide an avoided losses (adaptation benefits) to the tune of 2.2% of the delta’s GDP by 2050. Similarly, input subsidies in seeds, fertilisers and biofertilisers were found to buffer the shocks in agriculture by 10%, and buffer the GDP per capita by 3% (Arto et al., 2019).

Markandya and González-Eguino (2019) have estimated the adaptation costs and residual adaptation costs accrued due to insufficient adaptation using integrated assessment models. Using the residual damages as a measure of loss and damage, the authors have estimated adaptation costs and residual costs under scenarios of high damages–low discount rate and low damages–high discount rate. The estimates suggested adaptation costs of 182 and 193 billion USD by 2050, and 737 and 783 billion USD by 2100 for South Asia and East Asia, respectively, under the scenario of high damages–low discount rate. The residual costs for the same scenario were 289 and 76% for 2050 and 238 and 62% for 2100 for South Asia and East Asia, respectively. Estimates for low damages–high discount rate were significantly lower adaptation costs and residual costs for both of these sub-regions of Asia.

The CCA efforts can be characterised as fragmented, incoherent and lacking perspective (Ahmed et al., 2019a), and the picture on adaptation financing can be stated as similarly fragmented with very limited literature published in peer-reviewed journals. Adaptation financing is crucial for supporting vulnerable countries and enhances adaptation, as it is evident that the enhanced adaptation finance support has positively affected the pace of adaptation in low-income countries (Ford et al., 2015). At the organisational level, adaptation financing has provided multiple functions that include risk assessment functions, valuation functions and risk disclosure functions (Linnenluecke et al., 2016).

Of the total global public adaptation finance of 28 billion USD, East Asia and the Asia–Pacific attracted 46% of the total funding, while South Asian countries attracted only 9% of the total funding (UNEP, 2016). These differences reflect the capacity of countries to attract adaptation finance. Some of the important adaptation-targeted climate funds are Pilot Programmes for Climate Resilience, Green Climate Fund, and Least-Developed Countries Fund, and South Asian countries have significantly benefited from these dedicated climate funds. Due to the disaster implications of climate change, there is a need to allocate adaptation finances for DRR. Estimates suggest that East Asia and the Asia–Pacific in general allocated 27% of the total adaptation funds to DRR, while South Asia allocated 25% (Caravani, 2016). Low-income economies tend to allocate more adaptation funds to DRR (46%), while lower-middle-income economies allocated 22%.

The least developed countries lack the capacity to adapt to climate change and the Least Developed Country Fund (LDCF) has made significant contributions to adaptation in these countries (High agreement, limited evidence). Based on the interview-based field research in four least developed countries, Sovacool et al. (2017) opined that the LDCF projects are contributing to the adaptive capacity of these countries (Sovacool et al., 2017). They also found that these projects are taking a marginal approach, rather than a radical or transformational one, to adaptation.

Kissinger et al. (2019) have estimated the climate financing needs in the land sector under the Paris Agreement. The estimates suggested adaptation needs of 2.5 billion USD for Bangladesh, 40.5 million USD for Lao PDR and 31 million USD for Mongolia, for the forest sector alone (Low agreement, limited evidence).

Financing green growth and low-carbon development can provide resilience benefits (high agreement , limited evidence). Kameyama et al. (2016) have estimated the cost of low-carbon investments that can provide resilience benefits in Asia and reported that such low-carbon development will cost in the range of 125–149 billion USD annually. A combination of public, private, bilateral and multilateral funding sources, and carbon-market offsets, were suggested to achieve this level of funding. In terms of the total resources available, a combination of public, private and bi- and multi-lateral funding could help the region to raise as much as 222.3–412.5 billion USD annually, with a possibility to reach higher amounts depending on the future economic growth of countries in the region. Soil carbon sequestration in agricultural soils was found to be a win–win solution for both mitigation and adaptation as it can help improve soils while increasing farm yields and incomes of smallholders (Aryal et al., 2020a).

New adaptation financing sources have been emerging which could provide country-specific adaptation financing suiting local-level adaptation needs in Asia. The newly established Asia Infrastructure Investment Bank (AIDB), and newly emerging developing-country finance institutions, are known to provide an additional adaptation finance (Neufeldt et al., 2018); however, despite these emerging financial sources, the region will fall short of the adaptation target in the Paris Agreement (Neufeldt et al., 2018).

Adaptation cost estimates can vary between various studies due to the differences in methodologies they adopt. Some studies have conducted cost assessments using a combination of stakeholder consultations and quantitative modelling of climate-change impacts and adaptation (Ahmed and Suphachalasai, 2014), while others depended solely on the quantitative modelling. Studies also differ in the coverage of sectors too: they either have focused on the multiple vulnerable sectors (Ahmed and Suphachalasai, 2014) or on a single sector (Hossain et al., 2019). Studies have differed in their estimates depending on their ability to take into consideration the transition costs of sudden adaptation (Hossain et al., 2019), the nature of social cost and/or damage functions employed (Arto et al., 2019), the discount rates applied (Markandya and González-Eguino, 2019) and consideration for the effects of GHG mitigation on adaptation needs (Duan et al., 2019a). In addition, the assumptions made on the pace of adaptation in estimating adaptation costs can make a difference in adaptation cost estimates. Adaptation at a slow or normal pace could require more adaptation finance, as large amounts of damage are not eliminated, than when adaptation is implemented at a faster rate (Markandya and González-Eguino, 2019). Although there have been improvements in adaptation cost estimates, there is a need to address the issue of endogeneity (Kousky, 2014; Samuel et al., 2019). The vast majority of studies that rely on databases, such as EM-DAT, tend to suffer from such endogeneity problems due to their inability to control the causality between GDP and damages (Kousky, 2014). Costs attributable to non-economic losses and damages are the least reported and least quantified in the adaptation costs literature due to lack of sufficient, robust and accessible methodologies (Chiba et al., 2017; Chiba et al., 2019; Serdeczny, 2019). This is a major limitation in assessing adaptation costs and financial needs, and it can lead to gross underestimation of adaptation costs. A detailed description of issues related to non-economic losses and damages, and its importance in strengthening adaptation, is provided in Box 10.6 and Table 10.5.

Risk insurance approaches and tools have significantly evolved during recent years. The emphasis has been mainly on mitigating the adverse selection and moral hazard that have been the limitations of traditional area-based crop insurance approaches (He et al., 2019). This has been achieved by shifting the indemnity calculations on to the specific weather parameters and developing a weather index (Greatrex et al., 2015; Fischer, 2019). Technological applications in the development of insurance products have seen significant progress, including that of the blockchain and smart contracts (Gatteschi et al., 2018). There are technological developments in loss estimation, which has been a major limitation in the traditional insurance approaches in the past that either delayed the indemnity payment or misjudged the losses. Application of multi-model and multi-stage decision support systems has begun to make crop loss assessments for insurance more efficient (Aggarwal et al., 2020). Technological applications also include remote sensing (Di et al., 2017) and mobile phone app technologies (Meena et al., 2018) to provide accurate and quick damage assessments, and application of Internet-based indemnity approvals have enabled quick payment of indemnities (OECD, 2017b).

As against financing post-disaster relief and reconstruction, which has been the norm of disaster management for decades in Asia, the evolution of ex-ante risk financing in the form of risk insurance has seen a steady rise globally and in Asia. The rise in popularity for risk financing in general and insurance in specific stem from the observation that governments have recognised the burden of mainly financing the post-disaster relief and reconstruction only (Juswanto and Nugroho, 2017; UNESCAP, 2018c; ADB, 2019), and from the realisation of cost savings and efficiency that risk financing for risk mitigation brings overall risk reduction (high agreement , medium evidence). As a result, a gamut of risk-financing instruments have been introduced to finance DRR and CCA initiatives in Asia among which risk insurance has gained prominence for it provides a low-cost and easy option for individuals, provides an opportunity for the governments to effectively engage the private sector in implementation and has the ability to inculcate risk-aware decision making at various levels (high agreement , medium evidence) (Hazell and Hess, 2017; UNESCAP, 2018c).

Several Asian countries, including India, the Philippines and China, have a significant experience of offering agricultural insurance against typhoons, droughts and floods (Yang, 2018). For the most part, these insurance systems have followed a traditional indemnity-based insurance which faces several challenges in implementation including moral hazard and adverse selection, disagreements and delays in crop-damage assessments that relied upon crop-cutting experiments, often leading to a delay in processing indemnity payments, costly insurance premiums and poor insurance expansion (high agreement , robust evidence) (Patnaik and Swain, 2017; Ghosh et al., 2019). Other factors contributing to poor penetration of insurance include limited awareness on the importance of insurance, and poor access.

To tackle the problem of costly insurance premiums, governments have subsidised the premiums (Ghosh et al., 2019). Premium subsidies have been reported to undermine the ability to convey the real cost of risks by the insured (price distortion), and have encouraged adverse selection and moral hazard (Nguyen and Jolly, 2019). On the contrary, subsidies have been suggested to address the issue of adverse selection associated with the insurance (Zhao et al., 2017c).

Despite the fact that the insurance programmes are able to obtain high participation rates due to subsidised premiums, their impact on farmers’ income seems to be insignificant especially under the conditions of low indemnities, low guarantee and wide coverage (Zhao et al., 2016a). The subsidy burden of insurance on national governments is found to be significant with an estimated equivalent of 6 billion USD spent by China alone on insurance (Hazell et al., 2017). In addition, the insurance programmes in Asian countries are reporting higher producer claim ratios, and often governments have to spend more than the money being transferred to the insured through the insurance programmes (Hazell et al., 2017).

To address the issues associated with traditional indemnity insurance, efforts have been made to develop weather-index insurance in Asia that bases the payouts on the rainfall or temperature index, rather than on the direct damage measurements. The parametric insurance products help avoid the delays in insurance payouts as they are based on modelled risks, rather than actual damage measurements, and control the adverse selection and moral hazard, although basis risks could be increased due to improper matching of payouts with the index (De Leeuw et al., 2014). Index insurance is known to promote public–private partnerships that in turn will enhance the efficiency of overall programme delivery (Hazell and Hess, 2017). Several countries, including India, Bangladesh, Thailand, Indonesia, Myanmar and the Philippines, either are currently piloting or expanding the weather-index insurance (Surminski and Oramas-Dorta, 2014; Tyagi and Joshi, 2019). Index insurance is constantly expanding with an estimated 194 million farmers already enrolled in China and India, which is much lower than the potential number of farmers it can reach (Hazell et al., 2017).

Few significant bottlenecks that are limiting the scaling up of weather-index insurance include lack of reliable weather data, low density of weather stations leading to high basis risk, and limited data on damage and hazard for parametric modelling of the insurance (Shirsath et al., 2019). Several innovations are being tried and tested to overcome the limitations associated with the index insurance which include developing multiscale index insurance, application of remote sensing, smartphone-based near-surface remote sensing and building insurance based on vegetation indices instead of relying on weather data alone (Hufkens et al., 2019). Alternative indices, such as the NDVI, are being tested for their applications in designing index-based insurance in India (IFAD, 2017). Agro-meteorology-based statistical analysis and crop growth modelling have been suggested to calibrate and rectify faulty weather indices (Shirsath et al., 2019; Zhu et al., 2019). Establishing automatic weather stations can improve data accuracy while preventing the delay in acquiring the weather data (Sinha and Tripathi, 2016). These technological applications have already started finding space within insurance programmes designed by national governments in Asia. For example, the government of India has released new operational guidelines for the application of new technologies such as drones, remote sensing and mobile phone apps in implementation of the national agricultural insurance, which is the third largest insurance in the world (Department of Agriculture, 2019).

Despite these developments, several issues still seem to hinder the penetration of insurance in Asia. Issues such as lack of sufficient choices, lack of clear model, lack of legal support, limited or absence of proper monitoring and evaluation, and limited data for underwriters to properly evaluate claims have been suggested (Nguyen and Jolly, 2019). Low interest among the potential buyers due to unaffordable insurance premiums, lack of provision for partial-loss claim settlement, big hassles in the claim settlement process and lack of timely settlement of claims are reported (Parappurathu et al., 2017). In addition, insurance has been reported to have expanded the coverage of cash crops at the expense of drought-resistant subsistence crops with effects on natural capital and a potential increase in farmer’s vulnerability to market price fluctuations (Müller et al., 2017).

Regional catastrophic insurance pools have also received attention in Asia. With the formation of Southeast Asia Disaster Risk Insurance Facility (Haraguchi and Lall, 2019), the regional insurance pool has been introduced in Southeast Asia, initially being piloted in Lao PDR and Myanmar and to be expanded to the rest of the ASEAN region. Regional catastrophic insurance allows vulnerable countries to buffer climatic shocks by diversifying the risks beyond country boundaries.

Social protection (SP) encompasses initiatives that involve transfer income or assets to the poor, protect the vulnerable against risks to their livelihood, and enhance the social status and rights of the marginalised (Béné et al., 2014; Kothari, 2014). Social protection offers a wide range of instruments (e.g., cash transfers, insurance products, pension schemes and employment guarantee schemes) that can be used to support households that are exposed to climate changes (Bank, 2015). It also presents an opportunity to develop inclusive comprehensive risk management strategies to address L&D from climate change as well as a means to CCA (Aleksandrova, 2019).

Social protection programmes assist individuals and families, especially the poor and vulnerable, cope with crises and shocks, finds jobs, improve productivity, invest in the health and education of their children, and protect the ageing population (Bank, 2018b). Social protection that is well designed and implemented in a more long-term approach can enhance human capital and productivity, reduce inequalities, build resilience and empowerment, and end the inter-generational cycle of poverty (medium evidence, medium agreement ) as indicated from various experiences in the region such as (a) cash transfer programmes in Indonesia (Kwon and Kim, 2015), (b) the Benazir Income Support Programme in Pakistan (Watson et al., 2017), (c) the Chars Livelihoods Programme in Bangladesh (Pritchard et al., 2015) and (d) Minsei-in designated volunteer social workers in Japan (Boeckmann, 2016). A key consideration in strengthening resilience through SP programmes is to design with climate and disaster risk considerations in mind and implement in close synergy with existing programmes, such as on sustainable livelihoods, EWS and financial inclusion (Coirolo et al., 2013; Bank, 2018a).

Asia is already the most disaster-prone region in the world, with over 200,000 lives lost and almost 1 billion people affected by storms and floods alone between 2005 and 2014, while a heatwave in North and Central Asia in 2010 killed 56,000 people (United Nations, 2015). Climate change is increasing the frequency and intensity of these sudden and slow-onset disasters, among them, hydrological changes in major river basins where 1.5 billion people live (such as the Indus, Ganges, Brahmaputra, Mekong, Yellow, Yangtze, Tarim, Amu and Syr Darya rivers) (Bank, 2017a). According to the latest estimates of the International Labour Organisation (ILO), 55% of the global population (around 4 billion people) remain without any SP benefits, and the SP coverage gap is highest in Africa (82.2%) and the Asia–Pacific (61%) (ILO, 2017b).

Risks are generally amplified for people without SP or essential infrastructure and services, and for people with limited access to land and quality housing, especially those in exposed areas and informal settlements without secure tenure (ESCAP, 2017). Stateless people are disproportionately affected by climate change and disasters as they tend to reside in hazard-prone areas and their statues as non-citizens often limits access to assistance (Connell, 2015). The three main types of SP are: (a) social safety nets (also known as social assistance), which include conditional and unconditional cash transfers, public work programmes, subsidies and food stamps; (b) social insurance, which consists of contributory pensions and contributory health insurance; and (c) labour market measures, which include instruments such as unemployment compensation (Bank, 2018b). The potential for an integrated adaptive SP is not yet harnessed by policymakers in tackling the structural causes of vulnerability to climate change (Tenzing, 2019). Public works programmes (i.e., India’s Mahatma Gandhi National Rural Employment Guarantee Act, MGNREGA) should take into account climate risk in planning and support development of community assets to increase collective resilience.

Aligning SP with climate-change interventions is an attempt to develop more durable pathways out of poverty and climate vulnerability; examples from MGNREGA depicting the attempt to align through a mainstreaming approach has helped women and their households (Adam, 2015; Steinbach et al., 2016). On another note, the Catastrophe Insurance Framework, the first model introduced in Shenzen, China, provides timely relief for citizens and operates as a safety net, particularly for the poorest residents who do not have disposable income to cover the costs associated with bodily injuries arising from disasters (Telesetsky and He, 2016). The Department of Labour and Employment’s Integrated Livelihood and Emergency Employment Programme in the Philippines is part of the recovery efforts after Typhoon Haiyan, providing short-term wage employment, and facilitates entrepreneurship for people affected by natural calamities and economic shocks (Bank, 2018b).

In each of these instances, governments are using SP to protect populations suffering from climate change or are adversely affected by structural, pro-climate economic reforms (Hallegatte et al., 2015). However, additional research is still needed and new tools need to be developed to inform policy design and support the implementation of ‘green’ SP, as well as to measure the net-welfare impacts of such policies (Canonge, 2016). In order to enhance SP programmes, one of the cross-cutting issues is to discuss the linkages between gender roles and responsibilities, food security, agricultural productivity and the mediating role that SP programmes can have (Jones et al., 2017). Social protection has a potentially important role to play in contributing to food security and agricultural productivity in a gender-responsive way (Holmes and Jones, 2013). As such, experience from Challenging the Frontiers of Poverty Reduction: Targeting the Ultra Poor programme in Bangladesh has promoted social innovation by creating social and economic values, fostering microenterprises, increasing food security and fostering inclusive growth, all while empowering ultra-poor women (Emran et al., 2014; Mahmuda et al., 2014). Although there is increasing evidence that SP programmes are having a positive impact in terms of reducing vulnerability in women’s everyday lives (Jones et al., 2017), the transformative impact of these programmes is rare due to limitations in recognising women’s access to productive inputs and resources (Tanjeela and Rutherford, 2018; Cameron, 2019).

On the other hand, poor governance practices affect delivery of SP programmes and the ability of beneficiary households to reap the benefits from such support (Sijapati, 2017). In Nepal, a closer look at public expenditure shows that about 60% of the SP budget is used by social insurance programmes that predominantly consist of public-sector pensions (Babken Babajanian, 2014; Koehler, 2014). Towards this end, more effort is needed to improve its existing programmes so that there is an equality of opportunities, along with secured human rights. The example from Nepal’s Child Grant is an indicative of an incremental approach to social policy (Garde et al., 2017). Meanwhile, in the Philippines, despite the existence of flagship national interventions that cover a significant number of people in need and have clear and robust implementation rules, there are still many programmes with overlapping mandates and target population, and several gaps in their monitoring systems (Bank, 2018b).

Having an integrated SP information system would allow policymakers to better monitor inputs, outputs and outcomes (e.g., who the beneficiaries are, what they are receiving, at what frequency, what the existing gaps are) (OECD, 2017a; Samad and Shahid, 2018). Based on evidence from the assessments of three countries (Mongolia, Nepal and Vietnam), the political and institutional arrangements (i.e., the software) is as important as the technical fixes (i.e., the hardware) in the success of using information and communication technology for delivering SP programmes (ADB, 2016). By 2050, climate-induced migration will likely be a major policy aspect of the rural–urban nexus as slow-onset impacts of climate change in sub-Saharan Africa, South Asia and Latin America will likely force over 143 million people to migrate within their national borders (Kumari Rigaud, 2018). This will have major implications for SP systems, and therefore national SP strategies should be designed to anticipate and address climate-induced internal mobility (Schwan and Yu, 2017). For instance, it does not offer a solution for maintaining Indigenous cultures which are often strongly affected by, or even disrupted by, climate change (Olsson, 2014). Hence, an effective approach needs to combine different policy instruments to support protection, adaptation and migration (O’Brien et al., 2018).

Evidently, SP has been financed typically through the combination of government tax revenues and official development assistance, and the challenges of the increasing frequency and intensity of natural and economic crises are straining these traditional financial sources (Durán-Valverde, 2020). In this context, innovative financing schemes are seen as critical to achieve the sustainable financing of SP (Asher, 2015; UNICEF, 2019) via social and solidarity economy, as seen in women’s autonomous adaptation measures in precautionary savings and flood preparedness in Nepal (Banerjee et al., 2019), and self-help groups as development intermediaries (Anderson, 2019). Still, there are constraints of SP to reach those who are most vulnerable to climate change and other hazards due to their legal status, such as the fact that attention to forcibly displaced populations within the SP field has been limited (Sabates-Wheeler, 2019).

Government SP can attenuate the negative impacts in facing disasters, depending on the differences in political systems and the focus put on sociopolitical measures (medium evidence, medium agreement ), not only in restoring livelihoods but also in easing mental burdens faced by rural households in developing countries (Dalton et al., 2016; Kosec and Mo, 2017; Liebenehm, 2018). However, limited government capacities and fiscal feasibility may impede the expansion and effective implementation of SP as developing countries need further support to design, adjust and implement SP schemes effectively (Klonner, 2014; Schwan and Yu, 2017). Most countries have comprehensive strategies for both SP and climate change, but few have attempted to align them, as in practice they remain in separate institutional homes, governed by their own intra-sector coordination groups and funding channels (Steinbach et al., 2016; Bank, 2018b). Thus, significant knowledge gaps remain in terms of understanding the potential of SP to build long-term resilience to climate change (Ulrichs et al., 2019). Future efforts should be geared to develop climate-responsive SP policies that consider a broad range of issues including urbanisation and migration, the impact of green policies on the poor, access to essential health care and risks to socially marginalised groups (Aleksandrova, 2019). Along with strengthening links to climate information and EWS, finance for enabling SP systems to address climate-related shocks and stresses dynamically needs to be scaled up (Kuriakose et al., 2013; Ulrichs et al., 2019).

Asian areas with the least capacity to respond, such as the Himalayan region and densely populated deltas, are hit first and hardest by climate impacts (De Souza et al., 2015; Khan, 2017). Acknowledging the limitations in terms of capacity and coping mechanisms towards climate change, education, training and awareness building is central to sustaining long-term capacity building (Clemens et al., 2016). Education has a lot more to offer in terms of improvements in addressing climate change, particularly in the climate hotspots of Asia where mostly poor, disadvantaged communities vulnerable to climate change reside (Mani et al., 2018). In particular, when disseminated, climate-change awareness and information need more explanation (Steg et al., 2014; Wi and Chang, 2018; Cho, 2020). In addition, international and national support through institutions and financing is critical for successful capacity building (Hemachandra, 2019), which must be designed for the long term and be self-sustaining (Gustafson et al., 2018). National ownership by recipient countries and members of communities of capacity-building efforts is key to ensuring their success (Roberts and Pelling, 2016; Mikulewicz, 2017).

The need to develop tailored climate communication and education strategies for individual nations as public awareness and risk perceptions towards climate change vary greatly (medium evidence, high agreement ) (Lee et al., 2015a). Improving on, and investing in, basic education, climate literacy and location-based strategies of climate change are vital to enhance public engagement, societies’ adaptive capacity and support for climate action (Lutz et al., 2014c; Hu and Chen, 2016). As stated in the IPCC Special Report 1.5°C, sustainable development has the potential to significantly reduce systemic vulnerability, enhance adaptive capacity and promote livelihood security for poor and disadvantaged populations (Roy et al., 2018). Hence, various concepts are introduced to foster awareness, understanding, knowledge, participation as well as commitment towards managing climate change in a sustainable manner. One such concept is education for sustainable development (ESD), which is aimed at integrating the principles and practices of sustainable development in all aspects of education, and training individuals who will contribute to the realisation of a more sustainable society (Kitamura, 2017).

Climate-change education (CCE) is also now addressed in the context of ESD and allows for learners to understand the causes and consequences of climate change, and teaches them how to take action (Mochizuki and Bryan, 2015). Both ESD and CCE are gaining broader attention, for instance, in China (Han, 2015) and the Republic of Korea (Sung, 2015); however, development of policies and implementation of initiatives regarding ESD and CCE still face a handful of challenges which require a strong political will and consensus of key stakeholders (Læssøe and Mochizuki, 2015). Effective communication on CCE particularly for younger-generation engagement is also essential, as they are our future leaders as climate change is an inter-generational equity issue (Corner et al., 2015). Action for Climate Empowerment of Article 6 of the UNFCCC target youth as a major group for effective engagement in the formulation and implementation of decisions on climate change (UNFCCC, 2015). Increasing attention from countries in Asia, such as Thailand and India, will encourage innovative ways to provide adequately in educating and engaging youth in climate-change issues (Narksompong and Limjirakan, 2015; Dür and Keller, 2018).

An integrated approach to knowledge about climate change embraces both the importance in bridging knowledge of climate science and respecting IKLK, and should be at the heart of any effort to educate citizens to have a deeper understanding of the causes and consequence of climate change in a holistic manner (Aswani et al., 2018). Indigenous Peoples, comprising about 6% of the global population, play a crucial role in the fight against climate change for two interlinked reasons. First, they have a particular physical and spiritual relationship with land, water and associated ecosystems, and tend to be among the most vulnerable group to climate change (Magni, 2017). Second, they have a specialised ecological and traditional knowledge relevant to finding the best solutions to climate change (Rautela and Karki, 2015). Indigenous knowledge systems and resource management practices are important tools for both mitigating and adapting to climate change (Fernandez-Llamazares et al., 2015). Indigenous knowledge is increasingly recognised as a powerful tool for compiling evidence of climate change over time (Ahmed et al., 2016a). Knowledge of CCA and DRR provide a range of complementary approaches in building resilience and reducing the vulnerability of natural and human systems to the impacts of climate change and environmental hazards (Mall et al., 2019). The adaptation dimension involves developing knowledge and utilising existing IKLK, skills and dispositions to better cope with already evident and looming climate impacts (Aghaei et al., 2018). It is also important to ensure inclusive efforts in DRR across different nations and communities as well as increasing skills and capacities of women towards DRR efforts (Alam and Rahman, 2014; Drolet et al., 2015; Islam et al., 2016b; Reyes and Lu, 2016; Hemachandra et al., 2018). More effective and efficient teaching and learning strategies, as well as collaborative networks, are needed to increase preparedness and DRR activities across various levels of community (Oktari et al., 2015; Takahashi et al., 2015; Tuladhar et al., 2015b; Shiwaku et al., 2016; Gampell et al., 2017).

Table 10.6 shows education and capacity-building aspects affecting adaptation by sub-region examples.

Table 10.6 | Education and capacity-building aspects affecting adaptation by sub-regions examples

Capacity building at national and local levels still needs to address gaps in research and practice, such as impacts and results of different preparedness measures (Alcayna et al., 2016). Ad-hoc and localised documentations and monitoring of efforts to build adaptive capacities has rendered it difficult to assess success (Cinner et al., 2018). Recommendations for strengthened capacity building are sometimes made or understood in isolation from the underlying structural issues shaping vulnerability, or without adequately recognising the political relationships that mediate the ways in which particular technical interventions result in differentiated outcomes for different groups (Archer and Dodman, 2015). Thus, design- and decision-based tools, such as rapid assessment for community resilience to climate change as well as rapid approach to monitor the effectiveness of aid projects, support the community-based adaptation to climate change to analyse using a multi-dimensional approach, procedural, distributional, rights and responsibilities (Nkoana et al., 2018; Jacobson et al., 2019).

As a model of communication and engagement, citizen science has the potential to promote individual and collective climate-change action (Groulx et al., 2017). More than information provision is needed to mobilise public action on climate change (Kyburz-Graber, 2013). Citizen science links communication and engagement in a manner that holds important lessons on ways to promote collective responses to climate (Wals et al., 2014; Bonney et al., 2016). The power of science-based citizen engagement lies in citizen group contribution in drawing upon their local knowledge to enrich the knowledge base required for management decisions (Sayer et al., 2015). Scientific evidence may be less attuned to the complexity of local realities in managing climate change; thus, citizen science has the potential in bridging this gap and has many advantages for climate mitigation and adaptation practice and policy (Ford et al., 2016). While citizen science uses citizens as policy-passive objects for research in conducting measurements for big datasets, citizen social science is gaining momentum where it repositions citizens as central co-learners who can widen the climate-science evidence base to achieve a more holistic understanding for the benefit of all (Kythreotis et al., 2019).

There is growing evidence on the interconnectedness of extreme weather, climate change and disaster impacts (Asia, 2017; Reyer, 2017). In Asia, climate-related disasters have become more recurrent and destructive in terms of both economic and social impacts (Bhatt et al., 2015; Aich et al., 2017; Vij et al., 2017). Projections of increasing frequency, intensity and severity of climate-related disasters call for better integration of CCA and DRR (Sapountzaki, 2018) in policy development to address risks efficiently (Rahman et al., 2018) and to promote sustainable development pathways for reduced vulnerability and increased resilience (Seidler et al., 2018). Connecting CCA and DRR efforts in both policy and practice continue to be a challenge, however, because the convergence of national policy and planning processes on CCA and DRR within Asia is in its early stages (Cousins, 2014) and structural barriers persist (Mall et al., 2019). Both CCA and DRR have developed as separate policy domains because of the different temporal and spatial scales considered, the diversity of actors involved, the policies and institutional frameworks adopted and the differences in tools and methodological approaches used. This has resulted in the CCA and DRR communities, and the knowledge and research they produce to support planning and decision making, not always being well connected (Street et al., 2019).

Climate risk management in Asia is approached by focusing on hazards that are associated with extremes (i.e., extreme weather events with increased frequency and severity) as well as climate- and weather-related events. For example, farming has been affected by climatic variability and change in a wide variety of ways that include an increase in drought periods and intensity, a shortage of irrigation water availability, an increase in flooding and landslides, pest infestation of crops, a rising number of crop diseases, the introduction of invasive species and crop weeds, land degradation and an overall reduction in crop yields (Khanal et al., 2019). Estimation of the number of daily patients of heat-related illness based on the weather data and newly introduced metrics shows that the effects of age, successive days and heat adaptation are key variables (Kodera et al., 2019).

Because most developing countries in Asia are highly vulnerable to the impacts of climate change due to a number of factors, many studies have focused on understanding vulnerability, for instance, gendered vulnerability at the micro scale, which limits capacity to respond to both climatic and socioeconomic stressors (Ferdous and Mallick, 2019); vulnerability of urban poor communities due to the interaction of environmental and social factors (e.g., low incomes, gender, migrant status) and heightens the impacts of climate change on the poor (Porio, 2014); social–ecological vulnerability where a degraded environment influences hazard patterns and vulnerability of people (Depietri, 2020); and livelihood vulnerability due to perceived climate risks and adaptation constraints (Fahad and Wang, 2018; Hossain et al., 2020).

Risk assessments have been undertaken for different hazards such as flood (Al Saud, 2015; Al-Amin et al., 2019; Jha and Gundimeda, 2019; Mahmood et al., 2019; Zhang et al., 2019e), drought (Guo et al., 2019; Mainali et al., 2019), rainfall-induced landslide (Li et al., 2019b), SLR (Imaduddina and Subagyo, 2014; Suroso and Firman, 2018) and heat stress (Onosuka et al., 2019), among others, as well as environmental assessment, for example, in coastal zones (Islam and Zhang, 2019). Different types of strategies for climate risk management have also been studied including: (a)in situ adaptation through ecosystem- and community-based adaptation (Jamero et al., 2017); (b) managed retreat or relocation (Buchori et al., 2018; Doberstein et al., 2020); (c) planned sheltering in flood zones (Wu et al., 2019c); (d) sustainable livelihoods that consider long-term CCA measures of farmers and fishermen (Nizami et al., 2019; Shaffril et al., 2019); (e) coastal afforestation through mangrove plantation (Rahman et al., 2018); (f) management of ecosystem services to mitigate the effects of droughts (Tran and Brown, 2019); (g) pre-investments, including holistic assessment of the basin (Inaoka et al., 2019); (h) institutionalisation, where entry points are identified in efforts to build resilience (Lassa, 2019) and adaptive governance (Walch, 2019); and (i) linking science and local knowledge (Mehta et al., 2019; van Gevelt et al., 2019).

The sectors to which CCA and DRR have been linked are varied. For example, Filho et al. (2019) assessed adaptive capacity and resilience to climate change based on urban poverty, infrastructure and community facilities; Mabon et al. (2019) looked at adaptation via the built environment, green roofs, and citizen and private-sector involvement in smaller-scale greening actions; Lama and Becker (2019) focused on adaptation to reduce risk in conflicts; Banwell et al. (2018) studied the link between health, CCA and DRR; and Izumi et al. (2019) surveyed science, technology and innovation for DRR. Vulnerable groups have been given much attention, such as farmers (Afroz, 2017; Gupta et al., 2019; Jawid and Khadjavi, 2019; Khanal et al., 2019; Shi et al., 2019a), women (Goodrich et al., 2019; Hossain et al., 2019; Udas et al., 2019), and children, elderly and refugees (Asia, 2017). Finally, issues identified include water resource management (Bhatta et al., 2019; Sen et al., 2019; Zhang et al., 2019a); food security (Aleksandrova et al., 2016; Le, 2016); disaster governance (Blanco, 2015); climate boundary shifting wherein impacts of climate change are significant for crop production, soil management and DRR (Talchabhadel and Karki, 2019); and institutional dimensions of CCA (Cuevas, 2018; Islam et al., 2020).

Case studies on climate risk management and integrated CCA and DRR actions highlight some key lessons including: an integrated and transformative approach to CCA, which focuses on long-term changes in addressing climate impacts (Filho et al., 2019); adoption of an adaptive flood risk management framework incorporating both risk observation and public perceptions (Al-Amin et al., 2019); a holistic approach and non-structural and technological measures in flood control management (Chan, 2014); monitoring of changes in urban surface water in relation to changes in seasons, land covers, anthropogenic activities and topographic characteristics for managing watersheds and urban planning (Faridatul et al., 2019); removing ‘gender blindness’ in agrobiodiversity conservation and adaptation policies (Ravera et al., 2019); understanding uncertainties in CCA and DRR at the local level (van der Keur et al., 2016; Djalante and Lassa, 2019 ); promoting the use of IKLK alongside scientific knowledge (Hiwasaki et al., 2014); and increasing information, education and communication activities, and capacity development on DRR at the local level (Tuladhar et al., 2015a).

Several studies also have identified enabling conditions to effectively implement CCA and DRR actions. In the Arab region of Asia (ARA), the following are critical: capacity building to develop knowledge and awareness; mainstreaming CCA and DRR in the national strategies and policies (e.g., water and environmental strategies); empowering the role of CCA and DRR actors, notably women and rural societies; adopting lessons learned from regions with physical characteristics similar to those of ARA; establishing forecasting and prediction platforms that are supported by advanced monitoring technologies (e.g., remote sensing); and encouraging universities and research centres to develop studies on CCA and DRR. In Southeast Asia, laws and policies, institutional and financial arrangements, risk assessment, capacity building, and planning and implementation are entry points in integrating CCA and DRR (Lassa and Sembiring, 2017; Agency, 2018). According to Cutter et al. (2015), holistic solutions and integrated approaches, rigorous risk research that shows coherent science-based assessment and knowledge transfer from research to practice, and aligned targets on disaster risk management, climate change and sustainable development targets, are critical. Social capital and SP measures could promote pro-poor and gender-responsive adaptation as well as socially inclusive policies (Dilshad et al., 2019; Yari et al., 2019). Community-based approaches could allow local perceptions of climate change and experience of place to be included in planning (Dujardin et al., 2018; Dwirahmadi et al., 2019; Widiati and Irianto, 2019), and multi-stakeholder participation could engage various actors such as the private sector in CCA and DRR. Furthermore, multi-level climate governance could benefit from vertical and horizontal interactions at different levels and layers in the city (Zen et al., 2019). To mainstream and secure funding commitments, CCA and DRR could be integrated into national development plans and sectoral long-term plans (Ishiwatari and Surjan, 2020; Rahayu et al., 2020; Rani et al., 2020 b).

Adaptation follows knowledge on risks, and literature exists that systematically identifies and characterises exposure and vulnerability, but gaps still exist. Decision making under uncertainty is challenged by the lack of data for adapting to current and uncertain future climate, the different perceptions of risk, and the potential solutions across different cultures and languages (van der Keur et al., 2016). Lack of downscaled climatic data, diverse institutional structures, and missing links in policies, are among the challenges in South Asia (Mall et al., 2019). In agriculture, there are gaps in the use of advanced farming techniques such as drought-resistant crops, and information on climate change to support farming households in making adaptation decisions (Akhtar et al., 2019; Khanal et al., 2019; Ullah et al., 2019). Better understanding of effective water management is crucial due to conflicts for shared water in ARA (Shaban and Hamze, 2017; UNDP, 2018). For delta regions, gaps identified are methodologies and approaches appropriate for understanding social vulnerability at various scales, pathways required for adaptation policy and response in the deltas that transcend development, and the lessons from implemented policy and how practice can build on these lessons in the deltas, among others (Lwasa, 2015). Approaches in tackling the challenges of climate change and disasters in the cities of developing countries could be better understood, and shared between cities so they can learn from one another (Filho et al., 2019).

Food, energy, water and land are vital elements for sustainable development as well as enhancing resilience to both climatic and non-climatic shocks. All these resources are highly vulnerable to climate change (Sections 10.3.1, 10.3.4). Poor people are most affected due to changes in resources availability and accessibility. Food, water and energy security are interconnected (Bizikova et al., 2013; Ringler et al., 2013; Rasul, 2014; Chang et al., 2016; Ringler et al., 2016). Although adapting to climate change is one of the core components of the global, regional, national and subnational agendas, the focus of adaptation action has remained sectoral. Undermining the interlinkages of food, energy and water security may increase trade-offs between sectors or places, which may lead to maladaptation (Barnett and O’Neill, 2010; Howells et al., 2013; Lele et al., 2013). Therefore, focusing on the nature of trade-offs and synergies across the food–water–energy nexus for integrated management of resources is a potential strategy for adaptation to both climatic and non-climatic challenges (Bhaduri et al., 2015; Zaman et al., 2017). Due to its importance to the Paris Agreement and SDGs, the food–water–energy nexus approach has gotten increasing attention in terms of capturing synergies and minimising trade-offs in this interconnected system, which is also critical for enhancing adaptation together (Bazilian et al., 2011; Lawford et al., 2013; UNESCAP, 2013; FAO, 2014; Rasul and Sharma, 2014; Taniguchi et al., 2017a; Sukhwani et al., 2019; Sukhwani et al., 2020).

The food–water–energy nexus can be evaluated in the two-way interactions between water–food, water–energy and food–energy (Taniguchi et al., 2017a). The water–energy nexus includes water for energy and energy for water (Rothausen and Conway, 2011; Hussey and Pittock, 2012; Byers et al., 2014), the water–food nexus includes water for food and the impact of food production on water (Hoekstra and Mekonnen, 2012) and the energy–food nexus includes energy consumption for food production and food crops for biofuel production (Tilman et al., 2009). The food–water–energy–land nexus has diverse implications at the sub-regional level in Asia. The increase in the water-supply gap raises questions about the sustainability of the main mode of electricity generation in South Asia. Thermal power generation and hydropower generation are both threatened by water shortages in South Asia (Luo, 2018b; Mitra et al., 2021). Furthermore, policy-mismatch-driven anthropogenic causes lead to unsustainable water use for food production in India. For example, subsidised electricity supply for watering agriculture plays a key role in losing groundwater’s buffer capacity against the various changes including climate variabilities (Badiani et al., 2012; Mitra, 2017). In the Mekong River basin of Southeast Asia, massive and rapid export-oriented hydropower development will have direct implications on regional food security and livelihoods through a major negative effect on the aquatic ecosystem (Baran and Myschowoda, 2009; Dugan et al., 2010; Arias et al., 2014). Similarly, in Central Asia, the shifting of water storage for irrigation to power development has increased risks on reliable water supply and quality of water (Granit et al., 2012). Deforestation-driven agro-environmental changes have led to a decreased forest water supply, an increased irrigation water demand and a negative effect on cropland stability and productivity (Lim et al., 2017a; Lim et al., 2019b).

Many challenges remain in both scientific research and policy actions at the global, regional, national and subnational levels. The scientific challenges include data, information and knowledge gaps in understanding the food, energy, water and land interlinkages, and lack of systematic tools to address trade-offs (Liu et al., 2017a). Until very recently, implementation of the food–energy–water nexus focused primarily on technical solutions, whereas governance (i.e., the institutions and processes governing the food–energy–water nexus) has not received much consideration (Scheyvens and Shivakoti, 2019). At the policy end, the common challenges for implementation of the water–energy–food–land nexus are absence of sectoral coordination (Pahl-Wostl, 2019), the influence of political priorities on decisions and lack of processes for scientific knowledge to shape decisions, lack of capacity to understand interlinkages between sectors, lack of multi-stakeholder engagement in planning and decision-making processes, and lack of incentive mechanisms and adequate finance to support the approach (Bao et al., 2018; Scheyvens and Shivakoti, 2019).