Human activity is almost certainly affecting global climate change, according to a report released by several UA researchers Feb. 2.

For Tucson, this means even warmer temperatures and less rain if energy use and emission rates don’t fall, experts say.

“”In relation to global climate change, I would say that the U.S. as a nation has not been proactive,”” said Edella Schlager, an associate professor of public administration and policy who focuses on environmental policy.

The report, titled “”Climate Change 2007: The Physical Science Basis,”” uses strong language when discussing mankind’s effect on global climate change.

The report summarizes scientific findings aimed at environmental policymakers.

It was created by the Intergovernmental Panel on Climate Change, a group started in 1988 by the United Nations Environmental Program and the World Meteorological Organization.

The authors state they believe with “”very high confidence”” that human activity since 1750 has led to the warming of the Earth. The phrase “”very high confidence”” is defined in the report as a 90 percent certainty.

Julia Cole, an associate professor of geosciences, was a contributing author and is writing paragraphs in a longer, more technical IPCC report due out this spring.

“”To get 90 percent agreement is somewhat remarkable,”” Cole said. “”Each report has stated this in increasingly strong terms. Now we’re saying it’s definitely (the case).””

Jonathan Overpeck, a professor of geosciences and director of the UA’s Institute for the Study of Planet Earth, helped draft the report. He was in Washington, D.C. this week briefing Congress about the report and could not be reached for comment.

Data used in the report has offered scenarios about what climates different regions of the world can expect in the future if energy consumption and emissions rates continue as they are now.

The Tucson region can expect significantly warmer winters and summers as well as a 10 to 15 percent reduction of rainfall in the next century, said Travis Huxman, assistant professor of ecology and evolutionary biology.

“”Assuming people continue to use energy resources as they are now, those are the types of changes we can expect,”” Huxman said. “”We have the potential to offset that big change.””

What effect the report will have on environmental legislation is uncertain at this point, Schlager said.

“”I don’t think that we’ll wake up one morning and read on the front page that Congress has passed this wide-sweeping legislation,”” Schlager said. “”I think that what you’ll find in the U.S. will be a number of more modest steps, at least initially.””

Those involved with the report agree that discussion about global climate change is an important first step. Because the report is generating dialogue, Cole said, it could have a positive impact on human behavior.

“”I hope that this is a real wakeup call for people to do something about climate change, to move beyond the statement that we need to investigate it further,”” he said.