Climate Change 2001:
Synthesis Report
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Populations that inhabit small islands and low-lying coastal areas are at particular risk of severe social and economic effects from sea-level rise and storm surges. Tens of millions of people living in deltas, low-lying coastal areas, and on small islands will face risk of displacement. Further negative impacts will be increased by saltwater intrusion and flooding due to storm surges and loss of coastal wetlands and slowing down of river discharges.


Key uncertainties in the identification and quantification of impacts arise from the lack of reliable local or regional detail in climate change, especially in the projection of extremes, inadequate accounting in impacts assessments for the effects of changes in extremes and disasters, limited knowledge of some non-linear processes and feedbacks, uncertainties in the costing of the damage due to climate impacts, lack of both relevant data and understanding of key processes in different regions, and uncertainties in assessing and predicting the response of ecological and social (e.g., impact of vector- and water-borne diseases), and economic systems to the combined effect of climate change and other stresses such as land-use change, local pollution, etc.

Q3.13, Q4.10, & Q4.18-19
  Costs and Benefits of Adaptation and Mitigation Options

9.23 Adaptation is a necessity; its cost can be reduced by anticipation, analysis, and planning.

9.24 Adaptation is no longer an option, it is a necessity, given that climate changes and related impacts are already occurring. Anticipatory and reactive adaptation, which will vary with location and sector, has the potential to reduce adverse impacts of climate change, to enhance beneficial impacts, and to produce many immediate ancillary benefits, but will not prevent all damages. However, its potential is much more limited for natural systems than for human systems. The capacity of different regions to adapt to climate change depends highly upon their current and future states of socio-economic development and their exposure to climate stress. Therefore the potential for adaptation is more limited for developing countries, which are projected to be the most adversely affected. Adaptation appears to be easier if the climate changes are modest and/or gradual rather than large and/or abrupt. If climate changes more rapidly than expected in any region, especially with respect to climate extremes, then the potential of adaptation to diminish vulnerability of human systems will be lessened.

Q3.26-28 & Q3.33
9.25 The costs of adaptation can be reduced by anticipation and planned action, and many costs may be relatively small, especially when adaptation policies and measures contribute to other goals of sustainable development.

Q3.31 & Q3.36-37
9.26 Key uncertainties regarding adaptations relate to the inadequate representation by models of local changes, lack of foresight, inadequate knowledge of benefits and costs, possible side effects including acceptability and speed of implementation, various barriers to adaptation, and more limited opportunities and capacities for adaptation in developing countries. Q3.27

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