Democrats hope to shift the politics of climate change by highlighting what they say are the massive costs of failing to curb greenhouse-gas emissions.

The messaging push—in the form of a new White House report and a Senate hearing Tuesday—contradicts claims by the GOP that robust policies to cut carbon dioxide will hobble the economy.

Democrats insist that a much greater financial risk lies in ignoring the devastating impact of unchecked global warming. "Delaying action will increase the cost," said Jason Furman, chairman of the White House Council of Economic Advisers.

The CEA report released Tuesday attempts to estimate the long-term expense of avoiding steps to curb global emissions.

It arrives as the Environmental Protection Agency is crafting rules to cut emissions from coal-fired power plants, a plan that administration officials hope will provide leverage to win concessions from China and other nations in international climate talks.

One scenario that CEA modeled would allow global carbon emissions to accumulate enough to boost temperatures by 3 degrees Celsius above pre-industrial levels, rather than limiting the rise to 2 degrees, which is the target of international negotiations.

That one-degree difference would increase annual climate-related global economic damages—from coastal flooding, heat-related illness, and other harm—by an amount equivalent to roughly 1 percent of global economic output, the report concludes.

"To put this percentage in perspective, 0.9 percent of estimated 2014 U.S. Gross Domestic Product is approximately $150 billion. The incremental cost of an additional degree of warming beyond 3° Celsius would be even greater. Moreover, these costs are not one-time, but are rather incurred year after year, because of the permanent damage caused by increased climate change resulting from the delay," the report states.

Furman told reporters that the estimates are conservative.

The CEA report explores a second way in which delaying action causes economic damages mount. When policymakers eventually do attempt to stave off runaway temperature increases, the most cost-effective options won't be available anymore, the authors say.

"Delays mean that the target will be met in a less efficient manner. We will lose the opportunity to make investments that are consistent with low carbon emissions," Furman said.

Costs of curbing emissions increase by 40 percent for each decade of delay, according to the report, which is based on an analysis of existing studies.

Furman said that uncertainty about the timing, magnitude, and consequences of climate change is not a justification to put off emissions cuts.

Indeed, the report also says cutting emissions is a form of "climate insurance" against the "most severe and irreversible" potential consequences, such as temperature rises on the high end of scientific estimates if emissions continue unchecked.

The report is aimed at bolstering the case for the big EPA rules and other executive steps. On Tuesday the Energy Department is rolling out initiatives to help cut leaks of the potent greenhouse gas methane from natural-gas distribution and transmission lines.

Capitol Hill Democrats are similarly trying to put opponents of curbing emissions on the defensive.

A Senate Budget Committee hearing Tuesday will explore how "failing to mitigate the risks associated with climate change will affect the U.S. federal budget."

At the same time that Democrats are focusing on the financial fallout of climate change, private-sector climate advocates have stepped up their own efforts to stress the economic risks as well.

Last month, an initiative called "Risky Business"—led by former New York City Mayor Michael Bloomberg, former Treasury Secretary Henry Paulson Jr., and billionaire climate activist Tom Steyer—produced an analysis of regional economic vulnerabilities to climate change.

More recently, former Clinton-era Treasury Secretary Robert Rubin, who works with the Bloomberg-Paulson-Steyer group, penned a Washington Post op-ed late last week that calls on federal budget planners to begin reckoning more deeply with global warming.

"Future federal spending to deal with climate change is likely to be enormous and should be included in fiscal projections, whether in existing estimates or in an additional estimate that includes climate change," Rubin writes.

But Alabama Sen. Jeff Sessions, the top Republican on the Senate Budget Committee, isn't buying the arguments on the long-term costs of failing to implement policies such as carbon curbs on power plants.

"Inaction costs may be real, but certainly they are distant and somewhat uncertain. But the costs of action are certain right now. They are real and immediate," Sessions said at the outset of the Budget Committee hearing Tuesday.

"It's not enough just to say the danger is great, therefore we are free to demand the nation spend whatever is necessary, whatever the cost to be a leader in the world on these issues," he added, warning of regulations that result in higher power prices and act as a drag on the economy.

EPA estimates that its plan to cut emissions from existing power plants will impose compliance costs of up to $8.8 billion per year in 2030, but the agency's analysis also finds that public health and climate benefits would far outweigh those costs.

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