If the magnitude of global warming is consistent with the mid- or upper-range of the Intergovernmental Panel on Climate Change (IPCC) simulations, serious and damaging societal and ecological impacts are likely to result. Higher latitudes are predicted to see greater temperature increases than lower latitudes, especially during winter and spring. The IPCC predicts rising sea levels, increased rainfall rates and heavy precipitation events (especially over the higher latitudes) and higher evaporation rates that would accelerate the drying of soils following rain events. With higher sea levels, coastal regions could face increased wind and flood damage, and some models predict an increase the intensity of tropical storms.

Some climate change models predict an increased tendency toward drought over semi-arid regions. Arizona and other Western states have particular concerns about the impacts of climate change and climate variability on the environment, including the potential for prolonged drought, severe forest fires, warmer temperatures, increased snowmelt, reduced snow pack and other effects.

Even if temperature increases in the year 2100 are in the lower-range of the IPCC scenarios, the models project ongoing increases in temperatures and sea levels well beyond the end of this century. Thus the eventual impacts may be delayed but not avoided.

For more information on climate change impacts at the national and international levels:

• Intergovernmental Panel on Climate Change
• U.S. Environmental Protection Agency
• National Research Council, Climate Change Science: An Analysis of Some Key Questions (2001)
• Center for Health and the Global Environment, Climate Change Futures: Health, Ecological, and Economic Dimensions, Harvard Medical School, November 2005

For information on potential on impacts in Arizona and the West:

• Climate Assessment for the Southwest (CLIMAS)