Climate change poses "significant risks" to society, the National Academy of Sciences said yesterday, warning that delaying cuts in greenhouse gas emissions will make dealing with the problem harder in the future.

"Each additional ton of greenhouse gases emitted commits us to further change and greater risks," an academy panel said in a new report, which calls for the federal government to take a lead role in combating climate change at home and abroad.

Such advice runs counter to the political mood on Capitol Hill, where Senate Democrats recently defeated a Republican-led attempt to strip U.S. EPA of its ability to regulate carbon dioxide. That measure originated in the GOP-controlled House, which has also pushed for -- and won -- bruising budget cuts at federal environment and science agencies.

But the science academy's plain-spoken analysis, prepared in response to Congress' request for "action-oriented advice," warns of a "pressing need for substantial action to limit the magnitude of climate change and to prepare to adapt to its impacts."

"The risks associated with doing business as usual are a much greater concern than the risks associated with engaging in strong response efforts," the report adds. "This is because many aspects of an 'overly ambitious' policy response could be reversed if needed, through subsequent policy change; whereas adverse changes in the climate system are much more difficult (indeed, on the timescale of our lifetimes, may be impossible) to 'undo.'"

The analysis, prepared by a team of scientists, economists and engineers, also weighs in on the state of climate science, which it deems sound -- though it says some degree of uncertainty about the rate and severity of future climate change is inevitable.

"Given the inherent complexities of the climate system, and the many social, economic, technological, and other factors that affect the climate system, we can expect always to be learning more and to be facing uncertainties regarding future risks," the report says. "This is not, however, a reason for inaction."

In fact, said NAS committee chairman Albert Carnesale, "Uncertainty may be more of a need for taking action," because climate forecasts can't rule out the prospect that some impacts of climate change will be more severe than scientists now anticipate.

Report calls Congress to action, but are battle lines too hardened?
The report notes that climate change is already evident in the United States, where the average air temperature has risen 2 degrees Fahrenheit over the past 50 years, sea levels are rising along much of the coasts, patterns of rainfall and drought are changing, and Alaska's permafrost is warming.

Carnesale, chancellor emeritus at the University of California, Los Angeles, said his panel sought to make "policy-relevant" recommendations but stopped short of prescribing specific actions.

Those recommendations include calling for the federal government to take the lead on efforts to combat climate change with emissions cuts and programs to adapt to effects of warming that can't be avoided. Although several states and cities have put in place their own efforts to fight warming, the NAS panel said those piecemeal efforts aren't enough by themselves.

Similarly, action by the United States is key to international efforts to cut humans' greenhouse gas output, the report says.

"U.S. emissions alone will not be adequate to avert dangerous climate change risks," it notes, "but strong U.S. emission reduction efforts will enhance our ability to influence other countries to do the same."

Reaction to the report on Capitol Hill fell predictably along party lines.

Senate Foreign Relations Committee Chairman John Kerry (D-Mass.) called the NAS report "the latest watertight finding on the pile of countless peer-reviewed scientific studies that underscore the risks if the United States doesn't address climate change now, not in 10 or 20 years."

Rep. Henry Waxman (D-Calif.), who co-sponsored climate change legislation that passed the House in 2009 before sputtering to a halt in the Senate, was similarly blunt.

"Republicans in the House should be ashamed of their votes denying climate change and handcuffing the Environmental Protection Agency," he said. "If we wait to act, it may be too late to save the planet from irreversible changes."

Back in the Senate, Republican James Inhofe (Okla.), one of the chamber's most outspoken climate skeptics, dismissed the report by arguing that addressing climate change is simply too expensive.

"I appreciate the NRC's latest contribution to the scientific literature on the causes and impacts of climate change," Inhofe said. "What is clear and irrefutable is that the [academy's] proposals to address climate change would impose massive costs without meaningful benefits."

Click here to view the report.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500