Across the United States, impacts of climate change are already evident. Some extreme weather events such as heat waves have become more frequent and intense, cold extremes have become less frequent, and patterns of rainfall are likely changing. The proportion of precipitation that falls as rain rather than snow has increased across the western United States and Arctic sea ice has been reduced significantly.
To date, decisions related to the management and protection of the nation's people, resources and infrastructure have been based on records in the recent past, when climate was relatively stable. This book, part of the congressionally requested America's Climate Choices suite of studies, calls for a new paradigm - one that considers a range of possible future climate conditions and impacts that may be well outside the realm of past experience.