Climate change is happening in the Southwest, but southern Arizona can help mitigate the change, UA scientists told Rep. Gabrielle Giffords Saturday at a roundtable climate discussion.

The meeting was the result of a report published in part by university researchers about global climate change aimed at policymakers. Released by the Intergovernmental Panel on Climate Change, the report used strong language to describe the link between human activity and climate change.

The report stated with “”very high confidence”” there is a link between human activity since 1750 and global climate change. The phrase “”very high confidence”” means the link is 90 percent certain to exist.

Jonathan Overpeck, professor of geosciences and director of the UA’s Institute for the Study of Planet Earth,

was a contributing author of the report. Overpeck informed Giffords about climate change and its effect on sea levels.

Overpeck’s presentation painted a dire picture of climate in the Southwest if fossil fuel use continues as it is today.

The region will face increased temperatures, decreased precipitation and an increased probability of drought, Overpeck said.

“”We, of all the regions in the United States, need to do something,”” Overpeck said.

Average global temperatures have already increased by 0.8 degrees Celsius since the industrial revolution. Within the next century, the global temperature could increase by as much as 6.4 degrees Celsius, Overpeck said.

According to models used for the report, temperatures could increase by 10 degrees Fahrenheit during an Arizona summer. Droughts in southern Arizona would intensify, especially during winter months, stretching already slim water resources.

These increased temperatures could have effects on sea levels, too. Melting ice from Greenland and Antarctica would lead to higher sea levels that would cover low-lying coastal areas.Tom Swetnam, director of the laboratory of tree ring research at the UA and a professor of geography and regional development and dendrochronology, said climate change could have an effect on forest fires.

In the past five years, 18 percent of forested areas in North America were burned in forest fires, he said.

The combination of higher temperatures, less rainfall and invasive species to southwestern Arizona will lead to more forest fires in future years, Swetnam said.

“”It’s really a kind of perfect storm of all these things coming together,”” Swetnam said.

Community collaboration to remove invasive species and federal programs aimed at fire sciences policy and its relation to climate change should be emphasized to decrease forest fires.

Jim Shuttleworth, director of Sustainability of semi-Arid Hydrology and Riparian Areas, or SAHRA, and a professor of hydrology and water resources, spoke to Giffords about the effects that climate change will have on water supply in southern Arizona.

Tucson uses ground water and the Colorado River to supply the city. With more arid soil predicted for the future as well as a 40 percent drop in volume of the Colorado River, Tucson will need to find more sustainable water sources, Shuttleworth said.

“”Inevitably, if the temperature goes up, the demand for water and the demand for energy is going to increase, especially in this part of the world,”” Shuttleworth said.

Giffords said southern Arizona should explore possible alternative energy sources, such as solar power, and said the UA and Tucson community should be involved in efforts to mitigate global warming.

“”I believe that the American people want to be asked to be a part of the solution,”” Giffords said.

“”I don’t think that anyone wants to see their children and grandchildren inherit a planet that’s not as extraordinary as the one we have.””