A new report issued today by the U.S. Global Change Research Program outlines the extent of climate change around the U.S. and its effects not only at present but for the future as well.
The report, which draws from an expansive body of science and written by more than two dozen researchers, including Jonathan Overpeck from The University of Arizona, covers the impacts of climate change on both societal and environmental areas of the country. It was reviewed publicly and by other scientists, and approved by the National Oceanic and Atmospheric Administration and the White House Office of Science and Technology Policy. It is meant for both general audiences and decision makers.
Some of the key findings of the report are that global warming is unequivocal and primarily human-induced. Climate changes are underway and include increased stresses on water supplies, challenges to livestock and crop production, risks to costal areas from rising sea levels and storm surges, health risks, quality of life issues in urban areas and permanent changes to entire ecosystems.
One area of focus in the report is the southwestern U.S., where warming has been as rapid as anywhere in the country. Overpeck, a professor of geosciences and atmospheric sciences and co-director of the Institute for Environment and Society at the UA, has previously pointed to warmer temperatures in recent decades as a factor in the decline of spring snowpack in the mountains and lower streamflows in the Colorado River.
Overpeck is the lead author on the Southwest section of the report.
"It is becoming clear that the Southwest is the front line of ongoing climate change in the country, and the projections are for a much more serious set of problems if climate change isn't slowed dramatically," Overpeck said.
Several key issues are highlighted in the report. Scarcity will increase demand for water and likely generate conflicts over who gets a share. Warmer, drier conditions also make the region more susceptible to wildfires and invasive species, which not only threaten property owners but biological diversity in sensitive areas. Those conditions also increase the dangers associated with flooding.
"The greatest warming and impacts on water supplies are projected to affect the Colorado River Basin with a bulls-eye on Arizona. As a state, we have as much at stake as any other state in the country."
A phenomenon known as the urban heat-island effect is also projected to exacerbate summertime temperature increases, which the report said are projected to be greater than the annual average. Droughts, which are frequent in the Southwest, could become more severe. The cycle of increasing temperatures and decreased water supplies represent a challenge to the region which continues to lead the country in population growth.
Demand also for air conditioning in warmer weather increases the demand for electricity and the risks for brownouts and blackouts as utilities strain to keep up.
Farmers and ranchers also face risks. Besides less water for crops and herds, warmer temperatures also are detrimental to some specialty crops that depend on a period of colder temperatures in order to set fruit for the next harvest.
Recreation and tourism, two vital components to the regional economy, could also take a hit. Ski resorts, especially those on the southern parts of the western U.S., would have substantially shorter seasons. Hunting, fishing and boating activities could also feel the pinch.
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," Overpeck said. "Time is running out."