Adaptation refers to adjustments in ecological, social, or economic systems
in response to actual or expected climatic stimuli and their effects or impacts.
It refers to changes in processes, practices, and structures to moderate potential
damages or to benefit from opportunities associated with climate change.
Estimates of likely future adaptations are an essential ingredient in impact
and vulnerability assessments. The extent to which ecosystems, food supplies,
and sustainable development are vulnerable or "in danger" depends
both on exposure to changes in climate and on the ability of the impacted system
to adapt. In addition, adaptation is an important policy response option,
along with mitigation. There is a need for the development and assessment of
planned adaptation initiatives to help manage the risks of climate change.
Adaptations vary according to the system in which they occur, who undertakes
them, the climatic stimuli that prompts them, and their timing, functions, forms,
and effects. In unmanaged natural systems, adaptation is autonomous and reactive;
it is the process by which species and ecosystems respond to changed conditions.
This chapter focuses on adaptations consciously undertaken by humans, including
those in economic sectors, managed ecosystems, resource use systems, settlements,
communities, and regions. In human systems, adaptation is undertaken by private
decisionmakers and by public agencies or governments.
Adaptation depends greatly on the adaptive capacity or adaptability
of an affected system, region, or community to cope with the impacts and risks
of climate change. The adaptive capacity of communities is determined by their
socioeconomic characteristics. Enhancement of adaptive capacity represents a
practical means of coping with changes and uncertainties in climate, including
variability and extremes. In this way, enhancement of adaptive capacity reduces
vulnerabilities and promotes sustainable development.
Adaptation to climate change has the potential to substantially reduce many
of the adverse impacts of climate change and enhance beneficial impactsthough
neither without cost nor without leaving residual damage.
The key features of climate change for vulnerability and adaptation are
those related to variability and extremes, not simply changed average conditions.
Most sectors and regions and communities are reasonably adaptable to changes
in average conditions, particularly if they are gradual. However, these communities
are more vulnerable and less adaptable to changes in the frequency and/or magnitude
of conditions other than average, especially extremes.
Sectors and regions will tend to adapt autonomously to changes in climate
conditions. Human systems have evolved a wide range of strategies to cope
with climatic risks; these strategies have potential applications to climate
change vulnerabilities. However, losses from climatic variations and extremes
are substantial and, in some sectors, increasing. These losses indicate that
autonomous adaptation has not been sufficient to offset damages associated with
temporal variations in climatic conditions. The ecological, social, and economic
costs of relying on reactive, autonomous adaptation to the cumulative effects
of climate change are substantial.
Planned anticipatory adaptation has the potential to reduce vulnerability
and realize opportunities associated with climate change, regardless of autonomous
adaptation. Implementation of adaptation policies, programs, and measures
usually will have immediate benefits, as well as future benefits. Adaptation
measures are likely to be implemented only if they are consistent with or integrated
with decisions or programs that address nonclimatic stresses. The costs of adaptation
often are marginal to other management or development costs.
The capacity to adapt varies considerably among regions, countries, and
socioeconomic groups and will vary over time. The most vulnerable regions
and communities are those that are highly exposed to hazardous climate change
effects and have limited adaptive capacity. Countries with limited economic
resources, low levels of technology, poor information and skills, poor infrastructure,
unstable or weak institutions, and inequitable empowerment and access to resources
have little capacity to adapt and are highly vulnerable.
Enhancement of adaptive capacity is a necessary condition for reducing vulnerability,
particularly for the most vulnerable regions, nations, and socioeconomic groups.
Activities required for the enhancement of adaptive capacity are essentially
equivalent to those promoting sustainable development. Climate adaptation and
equity goals can be jointly pursued by initiatives that promote the welfare
of the poorest members of societyfor example, by improving food security,
facilitating access to safe water and health care, and providing shelter and
access to other resources. Development decisions, activities, and programs play
important roles in modifying the adaptive capacity of communities and regions,
yet they tend not to take into account risks associated with climate variability
and change. Inclusion of climatic risks in the design and implementation of
development initiatives is necessary to reduce vulnerability and enhance sustainability.
Current knowledge of adaptation and adaptive capacity is insufficient for
reliable prediction of adaptations; it also is insufficient for rigorous evaluation
of planned adaptation options, measures, and policies of governments. Climate
change vulnerability studies now usually consider adaptation, but they rarely
go beyond identifying adaptation options that might be possible; there is little
research on the dynamics of adaptation in human systems, the processes of adaptation
decisionmaking, conditions that stimulate or constrain adaptation, and the role
of nonclimatic factors. There are serious limitations in existing evaluations
of adaptation options: Economic benefits and costs are important criteria but
are not sufficient to adequately determine the appropriateness of adaptation
measures; there also has been little research to date on the roles and responsibilities
in adaptation of individuals, communities, corporations, private and public
institutions, governments, and international organizations. Given the scope
and variety of specific adaptation options across sectors, individuals, communities,
and locations, as well as the variety of participantsprivate and publicinvolved
in most adaptation initiatives, it is probably infeasible to systematically
evaluate lists of particular adaptation measures; improving and applying knowledge
on the constraints and opportunities for enhancing adaptive capacity is necessary
to reduce vulnerabilities associated with climate change.