There are many unique and threatened systems distributed over various regions
of the world. Although they are restricted to relatively narrow geographical
ranges, they can affect other entities beyond their range. The existence or
functioning of some of these systems is threatened by a small temperature change;
the existence or functioning of many others will be threatened by a medium to
large temperature change. These effects include impacts such as loss of many
species and ecosystems, disappearance of tropical glaciers, damage to coral
reefs, inundation of some low-lying islands, loss of coastal wetlands, and potential
harm to aboriginal societies and their cultures.
Many of these systems already are stressed by development, including pollution,
habitat destruction, encroachment for expansion of human habitation, and overextraction
of natural resources. The combination of climate change and societal development
puts these systems at greater risk. In some cases, climate change hastens the
destruction of these systems; in other cases it may result in the destruction
of systems that could survive societal stresses alone (e.g., small island states
and some mangrove ecosystems such as the Sundarbans).
Removing societal stresses and managing resources in a sustainable manner may
help some unique and threatened systems cope better with climate change.