Second, the economic and social costs of adaptation will increase the more rapidly climate change occurs. Third, although many opportunities exist for technological and behavioral adaptation, uncertainties exist about potential barriers and limitations to their implementation. Fourth, uncertainties exist about the efficacy and possible secondary effects of particular adaptive strategies. Water as a Common Resource Across Sectors and Subregions Water is a linchpin that integrates many subregions and sectors. Available water supplies will be directly affected by climate change, but they also are affected by changes in demand from the many sectors that rely upon the water.
Water is a scarce resource used in the agriculture, forest, and energy sectors.
It is used in urban areas and in recreational activities. It also is essential for the survival of wetlands, nonforest ecosystems, wildlife, and other ecological systems. Assessments of the potential impacts of climate change and variability on any of these systems and sectors must account for the inherent competition for water supplies and the need for water of varying qualities in various activities. For example, in an assessment of the potential impacts of climate change on agriculture, an assumption that farmers will be able to adapt to changing climatic conditions through a reliance on irrigation is valid only to the extent that water is available under future climate scenarios. In many cases, the scarcity of available water supplies will increase because of the direct effects of climate change on water, as well as increased demands for available water supplies.