10.4 Policy-relevant Scientific Questions in Climate Change Response
In this section a selected set of key policy-relevant scientific questions
is examined in some detail. It surveys new developments and new results to foster
our ability to make critical choices in climate policy, such as striking the
right balance between mitigation and adaptation, the timing and location of
actions, the costs of actions, and options to reduce and share them. After a
brief discussion of the broad climate policy portfolio, the focus is on mitigation
questions. The issues involved in these policy responses are structured as follows.
What should the response be? What are the most important factors to consider
in crafting a short- to medium-term portfolio of mitigation and adaptation actions,
and in acquiring information to resolve the large uncertainties? Drawing largely
on IAMs, Section 10.4.2 takes a closer look at the first
When should the response be made? The relationship between the timing of various
types of mitigation responses, their costs, and their social, economic, technological,
and environmental implications, raises a broad array of policy issues. The most
important insights are summarized in Section 10.4.3.
Where should the response take place? Closely related to the timing issue,
the location of mitigation responses is a multifacetted concern also. While
the environmental value of a given amount of unreleased GHG is equal wherever
its abatement takes place, there are far-reaching implications of whether and
to what extent nations are allowed to use international flexibility instruments.
The questions range from cost and efficiency concerns, to incentives for technological
development, to implementation and verification problems. Section
10.4.4 summarizes some of the aspects.
Who should pay for the response? The location of the mitigation action can
largely be separated from the question of who carries the costs. Numerous guidelines
have been proposed for burden sharing. They range from historical responsibility,
to various equity principles, to efficiency and international competitiveness
concerns. Some fundamental points are reviewed in Section
Towards what objective should the response be targetted? Current analyses of
climate change impacts, adaptations, and mitigation normally cover the range
between 450 and 850ppmv CO2-equivalent concentration or an increase
of between 1°C and 6°C in the global mean temperature. Completing the
circle that started with the discussion of how the costs and benefits of balancing
mitigation and adaptation activities influence the choice of the climate and/or
GHG stabilization target, the issue of high versus low levels of stabilization
is raised again in Section 10.4.6.