Climate change and the resulting rise in sea level are likely to exacerbate threats to buildings, roads, power lines, and other infrastructure in climatically sensitive places, such as low-lying coastlines and the permafrost regions of Alaska. Other stresses magnified by climate change. Climate change will very likely magnify the cumulative impacts of other stresses, such as air and water pollution and habitat destruction due to human development patterns. For some systems, such as coral reefs, the combined effects of climate change and other stresses are very likely to exceed a critical threshold, bringing large, possibly irreversible impacts. It is very likely that some aspects and impacts of climate change will be totally unanticipated as complex systems respond to ongoing climate change in unforeseeable ways.
Significant uncertainties remain in the science underlying climate-change impacts.
Further research would improve understanding and predictive ability about societal and ecosystem impacts, and provide the public with useful information about adaptation strategies. The potential impacts on water resources are an important issue in every region examined, although the nature of the concern is very different for the mountainous West than for the East. The potential for drought is a concern across the country. Forests are likely to grow more rapidly for a few decades because of increasing carbon dioxide concentrations in the atmosphere, but it is unclear whether those trends will be maintained as the climate system itself changes, leading to other disturbances such as fire and pest outbreaks. However, the climate change itself will, over time, lead to shifts in the tree species in each region of the country, some of them potentially quite profound.