Climate Change 2001: Synthesis Report

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3.26 Adaptation has the potential to reduce adverse effects of climate change and can often produce immediate ancillary benefits, but will not prevent all damages.

3.27 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.

WGII TAR Sections 18.2.3 & 18.3.5
3.28 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 4-1).

WGII TAR Sections 18.2.2, 18.3.3, & 18.3.5
3.29 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.

WGII TAR Sections 18.2.2 & 18.3.5
3.30 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.

WGII TAR Sections 5.3.4, 6.5.1, & 18.3.2
Table 3-6: Examples of adaptation options for selected sectors.
Adaptation Options
Water [WGII 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 water infiltration.
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, & 15.6; SRTT Section 11.2.1] 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 Section 15.4] 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 of fisheries.
Human health [WGII TAR Sections 7.5.4 & 9.11; WGII SAR Section 12.5; SRTT Section 14.4] 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.

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