Climate change is already underway in response to rising temperatures and CO2 concentrations. To mitigate the damages from future climate change, a substantial transformation of major economic sectors may be required. How much risk of damages should we permit and how much should we spend to try to offset the rest? To begin answering these questions, efforts to quantify the value of climate damages need to be considered. If we were confident of the damage estimates, we could compare them with estimates of the costs of mitigating and adapting to climate change in an overall cost-benefit analysis. But a point estimate is insufficient; the risks of being wrong about our cost forecasts also need to be weighed.

DAMAGE ESTIMATES

A wide variety of studies have tried to evaluate likely damages from climate change. Many have focused on specialized aspects of the problem, such as the effects on agricultural production in a particular region. Comprehensive studies are rarer, and even these efforts typically fail to include components that are especially difficult to estimate. Moreover, unresolved methodological issues have potentially profound effects on the predicted monetary losses.

As noted in the previous chapter, the major impacts of climate change will be felt on coastal regions, agriculture, health, and ecosystems. Economic losses to coastal areas could come from sea level rise, increased storm damage, and forced migrations. Over wider geographic areas, the production of crops, livestock, and fisheries will be affected.