||Adaptation has the potential to reduce
adverse effects of climate change and can often produce immediate ancillary
benefits, but will not prevent all damages.
|| Numerous possible adaptation options
for responding to climate change have been identified that can reduce adverse
and enhance beneficial impacts of climate change, but will incur costs.
Quantitative evaluation of their benefits and costs and how they vary across
regions and entities is incomplete. Adaptation to climate change can take
many forms, including actions taken by people with the intent of lessening
impacts or utilizing new opportunities, and structural and functional changes
in natural systems made in response to changes in pressures. The focus in
this report is on the adaptive actions of people. The range of options includes
reactive adaptations (actions taken concurrent with changed conditions and
without prior preparation) and planned adaptations (actions taken either
concurrent with or in anticipation of changed conditions, but with prior
preparation). Adaptations can be taken by private entities (e.g., individuals,
households, or business firms) or by public entities (e.g., local, state,
or national government agencies). Examples of identified options are listed
in Table 3-6. The benefits and costs of adaptation
options, evaluation of which is incomplete, will also vary across regions
and entities. Despite the incomplete and evolving state of knowledge about
adaptation, a number of robust findings have been derived and summarized.
TAR Sections 18.2.3 & 18.3.5
||Greater and more rapid climate change
would pose greater challenges for adaptation and greater risks of damages
than would lesser and slower change. Key features of climate change
to be adapted to include the magnitudes and rates of changes in climate
extremes, variability, and mean conditions. Natural and human systems have
evolved capabilities to cope with a range of climate variability within
which the risks of damage are relatively low and ability to recover is high.
Changes in climate that result in increased frequency of events that fall
outside the historic range with which systems have coped, however, increase
the risk of severe damages and incomplete recovery or collapse of the system.
Changes in mean conditions (e.g., increases in average temperature), even
in the absence of changes in variance, can lead to increases in the frequencies
of some events (e.g., more frequent heat waves) that exceed the coping range,
and decreases in the frequencies of others (e.g., less frequent cold spells)
(see Question 4 and Figure
TAR Sections 18.2.2, 18.3.3, &
||Enhancement of adaptive capacity can
extend or shift ranges for coping with variability and extremes to generate
benefits in the present and future. Many of the adaptation options
listed in Table 3-6 are presently employed to cope
with current climate variability and extremes, and their expanded use can
enhance both current and future capacity to cope. But such efforts may not
be as effective in the future as the amount and rate of climate change increase.
TAR Sections 18.2.2 & 18.3.5
||The potential direct benefits of adaptation
are substantial and take the form of reduced adverse and enhanced beneficial
impacts of climate change. Results of studies of future impacts of
climate change indicate the potential for adaptation to substantially reduce
many of the adverse impacts and enhance beneficial impacts. For example,
analyses of coastal flood risks from storm surges estimate that climate
change-driven sea-level rise would increase the average annual number of
people flooded many-fold if coastal flood protection is unchanged from the
present. But if coastal flood protection is enhanced in proportion to future
GDP growth, the projected increase is cut by as much as two-thirds (see
Figure 3-6). However, estimates such as these
indicate only potential benefits from adaptation, not the likely benefits -- as
analyses generally use arbitrary assumptions about adaptation options and
obstacles, often omit consideration of changes in climate extremes and variability,
and do not account for imperfect foresight.
TAR Sections 5.3.4, 6.5.1, &
3-6: Examples of adaptation options for selected sectors.
TAR Sections 4.6 & 7.5.4;
WGII SAR Sections 10.6.4 & 14.4]
||Increase water-use efficiency with "demand-side"
management (e.g., pricing incentives, regulations, technology standards).
Increase water supply, or reliability of water supply, with "supply-side"
management (e.g., construct new water storage and diversion infrastructure).
Change institutional and legal framework to facilitate transfer of
water among users (e.g., establish water markets).
Reduce nutrient loadings of rivers and protect/augment streamside
vegetation to offset eutrophying effects of higher water temperatures.
Reform flood management plans to reduce downstream flood peaks; reduce
paved surfaces and use vegetation to reduce storm runoff and increase
Reevaluate design criteria of dams, levees, and other infrastructure
for flood protection.
|Food and fiber [WGII
TAR Sections 5.3.4-5; WGII SAR Sections 2.9, 4.4.4, 13.9, &
||Change timing of planting, harvesting,
and other management activities.
Use minimum tillage and other practices to improve nutrient and moisture
retention in soils and to prevent soil erosion.
Alter animal stocking rates on rangelands.
Switch to crops or crop cultivars that are less water-demanding and
more tolerant of heat, drought, and pests.
Conduct research to develop new cultivars.
Promote agroforestry in dryland areas, including establishment of
village woodlots and use of shrubs and trees for fodder.
Replant with mix of tree species to increase diversity and flexibility.
Promote revegetation and reforestation initiatives.
Assist natural migration of tree species with connected protected
areas and transplanting.
Improve training and education of rural work forces.
Establish or expand programs to provide secure food supplies as insurance
against local supply disruptions.
Reform policies that encourage inefficient, non-sustainable, or risky
farming, grazing, and forestry practices (e.g., subsidies for crops,
crop insurance, water).
|Coastal areas and marine fisheries [WGII
TAR Sections 6.6 & 7.5.4;
WGII SAR Section 16.3; SRTT
||Prevent or phase-out development in coastal
areas vulnerable to erosion, inundation, and storm-surge flooding.
Use "hard" (dikes, levees, seawalls) or "soft"
(beach nourishment, dune and wetland restoration, afforestation) structures
to protect coasts.
Implement storm warning systems and evacuation plans.
Protect and restore wetlands, estuaries, and floodplains to preserve
essential habitat for fisheries.
Modify and strengthen fisheries management institutions and policies
to promote conservation of fisheries.
Conduct research and monitoring to better support integrated management
|Human health [WGII
TAR Sections 7.5.4 & 9.11;
WGII SAR Section 12.5; SRTT
||Rebuild and improve public health infrastructure.
Improve epidemic preparedness and develop capacities for epidemic
forecasting and early warning.
Monitor environmental, biological, and health status.
Improve housing, sanitation, and water quality.
Integrate urban designs to reduce heat island effect (e.g., use of
vegetation and light colored surfaces).
Conduct public education to promote behaviors that reduce health risks.
|Financial services [WGII
TAR Section 8.3.4]
|Risk spreading through private and public
insurance and reinsurance.
Risk reduction through building codes and other standards set or influenced
by financial sector as requirements for insurance or credit.