A new White House report makes the economic case for pursuing policies to curb climate change now, arguing that delaying policy changes will significantly increase the cost of action -- and potentially put the nation at risk. The report also defends newly proposed Environmental Protection Agency rules at a time when the proposed policy changes have become midterm campaign fodder.

"The signs of climate change are all around us," says the report, produced by the White House's Council of Economic Advisers, citing the results of the recently published National Climate Assessment.

The new report notes that harms from greenhouse gas emissions aren't reflected in the price of carbon-based energy. Consequently, it says government action is necessary to make up for this market failure and "thereby to limit the damage to economies and the natural world from further climate change."

The costs of inaction could be large, the report says, citing economic estimates that letting the Earth's temperature rise 3 degrees Celsius above preindustrial levels, instead of 2 degrees, could increase economic damages by about 0.9 percent of global output.

"To put this percentage in perspective, 0.9 percent of estimated 2014 U.S. Gross Domestic Product (GDP) is approximately $150 billion," the report notes. "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 gives specific examples of how climate change would impact the economy. For instance, it cites research showing that when the temperature in the U.S. rises above 100 degrees Fahrenheit, the labor supply in outdoor industries declines by up to one hour a day relative to temperatures 20 to 25 degrees cooler.

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Furthermore, the longer policies to curb climate change are delayed, the costlier they are to implement the report says. "An analysis of research on the cost of delay for hitting a specified climate target (typically, a given concentration of greenhouse gases) suggests that net mitigation costs increase, on average, by approximately 40 percent for each decade of delay," it says.

The report also makes the case that action to curb climate change "can be thought of as 'climate insurance' taken out against the most severe and irreversible potential consequences of climate change. Events such as the rapid melting of ice sheets and the consequent increase of global sea levels, or temperature increases on the higher end of the range of scientific uncertainty, could pose such severe economic consequences as reasonably to be thought of as climate catastrophes."

The Council of Economic Advisers specifically makes the case for new carbon limits that the EPA has proposed. The proposed rule would require the existing plants to reduce carbon dioxide emissions by 30 percent from 2005 levels by 2030. Republicans have dismissed the proposed policy changes, skewering President Obama and his party as anti-coal.

The proposed EPA rule, the report notes, would generate $27 billion to $50 billion in net benefits annually by 2020 and as much as $49 billion to $84 billion in 2030.

While Congress is unlikely to do anything to address climate change this year, particularly in the GOP-led House, Democrats are keeping up discussion about the issue. On Tuesday, a subpanel of the Senate Committee on Environment and Public Works is hosting a hearing on the effects of unchecked climate change. The panel plans to hear from a local Florida official, economists and others.