Several top U.S. government climate change scientists released a new report on Tuesday warning that the effects of global warming will become more severe unless the Obama administration takes action quickly.
For years, scientists have talked about the threat of rising sea levels on remote tropical islands and melting ice in the polar regions. But a new report by the U.S. Global Climate Research Program makes the threat of global warming personal.
"Climate change is happening now and it's happening in our own backyards, and it affects the kinds of things people care about," said Jane Lubchenco.
Jane Lubchenco is the head of the U.S. National Oceanic and Atmospheric Administration. She says the report presents scientific evidence that will inform policy making.
The report, compiled by more than 30 scientists at 13 U.S. government agencies, describes climate-related changes that are happening in the United States.
Tom Karl, was a principal author of the report.
"U.S. average temperature has risen by 1.5 degrees Fahrenheit over the past 50 years," said Tom Karl. "We've had more rain coming in heavy downpours that can lead to flooding. Less winter precipitation is falling as snow, more as rain."
The report, commissioned by the White House, uses climate models to project what will happen if action is not taken to reduce the carbon dioxide emissions that most scientists say cause global warming.
It predicts increasingly deadly heat waves, and higher incidents of asthma and diseases transmitted through the water and by insects and rodents.
Jerry Melillo, an author and director of the Ecosystems Center at the Marine Biological Laboratory in Massachusetts, says U.S. coastlines are under particular threat of rising sea levels and stronger hurricanes.
He points specifically to the U.S. coast along the Gulf of Mexico, where seven of the nation's 10 biggest seaports are located and two-thirds of all U.S. oil imports are transported.
"Vital energy and transportation infrastructure will be at risk with expected sea level rise and associated storm surge," said Jerry Melillo.
The report says the most severe affects of climate change can be avoided if action is taken swiftly to reduce heat-trapping gasses.
Not everyone is convinced. William Gray, a professor emeritus at Colorado State University's Department of Atmospheric Science, is one of the skeptics.
He says some scientists are placing too much emphasis on the role of greenhouse gases in climate change.
"There's no way they can warm the way the models say they do warm," said William Gray.
Gray says the rising temperatures are caused by natural fluctuations in the oceans' salinity levels.
"I think this whole thing in 10, 15, 20 years as we look back on this, and as we learn more, we'll see that this was a great exaggeration," he said.
Scientists are not the only people debating climate change. The U.S. Congress is considering legislation on how to tackle the problem. And international negotiators from 182 nations are working on a roadmap to fight global warming.
Negotiators have to come up with a plan to replace the Kyoto Protocol on greenhouse gas emissions by December, when they present their proposal at a United Nations conference in Copenhagen.