IPCC Fourth Assessment Report: Climate Change 2007
Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability

7.6 Adaptation: practices, options and constraints

7.6.1 General perspectives

Challenges to adapt to variations and changes in environmental conditions have been a part of every phase of human history, and human societies have generally been highly adaptable (Ausubel and Langford, 1997). Adaptations may be anticipatory or reactive, self-induced and decentralised or dependent on centrally-initiated policy changes and social collaboration, gradual and evolutionary or rooted in abrupt changes in settlement patterns or economic activity. Historically, adaptations to climate change have probably been most salient in coastal areas vulnerable to storms and flooding, such as the Netherlands, and in arid areas needing water supplies; but human settlements and activities exist in the most extreme environments on earth, which shows that the capacity to adapt to known conditions, given economic and human resources and access to knowledge, is considerable.

Adaptation strategies vary widely depending on the exposure of a place or sector to dimensions of climate change, its sensitivity to such changes, and its capacities to cope with the changes (Chapter 17). Some of the strategies are multi-sectoral, such as improving climate and weather forecasting at a local scale, emergency preparedness and public education. One example of cross-cutting adaptation is improving information and institutions for emergency preparedness. Systematic disaster preparedness at community level has helped reduce death tolls; for instance, new warning systems and evacuation procedures in Andhra Pradesh, India, reduced deaths from coastal tropical cyclones by 90%, comparing 1979 with 1977 (Winchester, 2000), and poor societies in other parts of the Bay of Bengal area have undertaken practical measures to reduce flood risks due to high levels of awareness and motivation among local communities. However, the effectiveness of such systems in reaching marginal populations, and their responses to such warnings, is uneven; and the timing of decisions to adapt affects the likely benefits.

Other strategies are focused on a sector, such as water, energy, tourism and health (see Chapters 3 and 8). Some are geographically focused, such as coastal area and floodplain adaptations, which can involve such initiatives as changing land uses in highly vulnerable areas and protecting critical areas. Adaptation, in fact, tends very often to be context-specific, within larger market and policy structures (Adger et al., 2005a), although it generally takes place within the larger context of globalisation (Benson and Clay, 2003; Sperling and Szekely, 2005).

There is a considerable literature on adaptations to climate variation and on vulnerabilities to extreme events, especially in developed countries; but research on potentials and costs of adaptation by industry, settlement and society to climate change is still in an early stage (Chapter 17). One challenge is that it is still difficult to project changes in particular places and sectors with much precision, whether by downscaling global climate models or by extrapolating from past experience with climate variation. Uncertainty about the distribution and timing of climate-change impacts at the local level makes judgments about the scale and timing of adaptation actions very difficult. Where there are co-benefits between climate-change adaptation and other economic or social objectives, there will be reasons for early action. In other cases, limits on predictability tend to delay adaptation (Wright and Erickson, 2003). In addition, there is little scientific basis as yet for assessing possible limits of adaptation, especially differences among locations and systems. In particular, the knowledge base about costs of adaptation is less well developed than the knowledge base about possible adaptation benefits. At least in some cases, costs might exceed actual benefits.