This Assessment has identified many remaining uncertainties that limit our ability to fully understand the spectrum of potential consequences of climate change for our nation. Additional research is also needed to improve under-standing of ecological processes that are sensitive to climate, and of the economic costs and benefits of a changing climate to Americans. Temperature increases will vary some-what from one region to the next. Heavy and extreme precipitation events are likely to become more frequent, yet some regions will get drier. The potential impacts of climate change will also vary widely across the nation.
Ecosystems are highly vulnerable to the projected rate and magnitude of climate change.
A few, such as alpine meadows in the Rocky Mountains and some barrier islands, are likely to disappear entirely, while others, such as forests of the Southeast, are likely to experience major species shifts or break up. The goods and services lost through the disappearance or fragmentation of certain ecosystems are likely to be costly or impossible to replace. Drought is an important concern in every region. Floods and water quality are concerns in many regions. Snowpack changes are especially important in the West, Pacific Northwest, and Alaska.