Scientists and researchers representing 13 U.S. government science agencies, major universities and research institutes produced the most comprehensive report to date on national climate change, offering the latest information on rising temperatures, heavy downpours, extreme weather, sea level changes and other results of climate change in the U.S.
The 190-page report entitled "Global Climate Change Impacts in the United States" is a product of the interagency U.S. Global Change Research Program, led by the National Oceanic and Atmospheric Administration.
Examining climate change effects region by region, the study details how the nation's transportation, agriculture, health, water and energy sectors will be affected in the future. And written in accessible language, the intent is to better inform members of the public and policymakers about the social, environmental and economic costs of climate change.
In a press conference today, University of Illinois Harry E. Preble Professor of Atmospheric Sciences Don Wuebbles, a contributor to the assessment, outlined the current and predicted effects of climate change in the Midwest U.S.
"We well recognize that the earth's climate varies naturally and has been warmer and cooler in the past," Wuebbles said. "But we also know that the climate changes we are experiencing today are largely the result of human activities."
Average temperatures have risen in the Midwest in recent decades, Wuebbles said, especially in winter. The growing season has been extended by one week. Heavy downpours are now twice as frequent as they were a century ago, he said, and the Midwest has experienced two, record-breaking floods in the past 15 years.
These trends are expected to continue into the future, Wuebbles added. Average annual temperatures are expected to increase by about two degrees Fahrenheit over the next few decades, and by as much as seven to 10 degrees by the end of the century, he said, with more warming projected for summer than winter.
Precipitation is expected to increase in the winter and spring, while summer precipitation will likely decline.
"More of the precipitation is likely to occur during heavier events," Wuebbles said.
As temperatures and humidity increases, heat waves, reduced air quality and insect-borne diseases are more likely to occur. Pollen production and the growth of fungi will also be stimulated, he said.
Heavy downpours can overload drainage systems and water treatment facilities, increasing the risk of waterborne diseases, he said.
The Great Lakes, which contain 20 percent of the planet's fresh surface water, will also be affected by the changing climate, Wuebbles explained. Depending on the extent of climate change, average water levels in the Great Lakes could drop by as much as two feet in this century, he said. This would affect beaches, coastal ecosystems, fish populations, dredging requirements and shipping.
Some of the effects of the changing climate are inevitable and will require human and animal populations to adapt, Wuebbles said. Other effects can be mitigated by limiting future emissions of carbon dioxide and other greenhouse gases that contribute to climate change, he said.
The report focuses primarily on the impacts of climate change, but it also addresses activities that could potentially mitigate those effects and adapt to changes as well. Measures in populated areas include rainwater harvesting and better urban planning to reduce urban heat island effects. In rural areas, more effective planning and management would help to slow the growing wildfire risk.
One example of planning public works to accommodate the possible risk of rising sea levels is a new sewage treatment plant in Massachusetts. The plant was built nearly two feet higher than originally planned in anticipation of a projected rise in coastal waters, a relatively inexpensive change that will keep it operational through its planned closure in 2050.
"The report lays out what is ahead for our country if we fail to act to curb climate change, and if we fail to act aggressively," said Jonathan Overpeck, co-director of the Institute for Environment and Society at the University of Arizona and lead author of the Southwest section of the report. "Time is running out."
The full report, "Global Climate Change Impacts in the United States" is available online at http://www.globalchange.gov/usimpacts.
