BUSH’S E.P.A. CHIEF ADOPTED OBAMA ADMINISTRATION LINE…. In light of today’s hearing at the House Energy and Commerce Committee, this seems like a pretty big deal. (thanks to ethan for the tip)

An Environmental Protection Agency administrator under President George W. Bush told the former president in 2008 that his administration was obliged to declare that emissions of heat-trapping greenhouse gases linked to climate change endanger public health and welfare.

Stephen Johnson, the EPA’s administrator from 2005 until 2009, also suggested in a Jan. 31, 2008 letter that the agency propose regulations to limit greenhouse-gas emissions from automobiles and from other human sources — a stance that the Obama administration has taken.

This is something of a bombshell in the climate debate. Late last year, President Obama’s EPA chief, Lisa Jackson, concluded that carbon emissions endanger public health and welfare — the so-called endangerment finding — which is the step preceding regulating emissions through the Clean Air Act.

The Republican line — outside of the belief that the entirely of climate science is some kind of communist plot — is that legislation is needed to overturn the EPA’s endangerment finding, so that efforts to combat the climate crisis can be stopped before they start. Dems, in turn, are waving around Stephen Johnson’s letter to make the obvious political point.

“As administrator Johnson’s letter makes clear, both Republican and Democratic administrations have had the same view of the science: carbon emissions are a serious threat to our nation’s welfare,” Rep. Henry Waxman (D-Calif.) wrote yesterday in a letter to the committee’s chairman, Rep. Fred Upton (R., Mich.). “I urge you to leave the science to scientists and drop your effort to use legislation to overturn EPA’s endangerment finding.”

Upton responded by accusing Waxman of “conspiring with the EPA.”

Republicans sure do love their conspiracies, don’t they?

In any case, Bush’s former EPA chief — who, admittedly, did not prefer the Clean Air Act as the ideal mechanism for regulating emissions — said it’s possible to use the law in a way “that is prudent and cautious yet forward thinking” and which “creates a framework for responsible, cost-effective and practical actions.” In other words, the Bush administration and the Obama administration are saying the same thing.

Johnson’s 2008 letter also argued that “the latest science of climate change requires the agency to propose a positive endangerment finding, as was agreed to at the cabinet-level meeting in November.”

Whatever happened after that cabinet-level agreement in the Bush administration? It turns out Bush quashed the effort, after Dick Cheney and Exxon Mobil “explained” the situation to him.

Nevertheless, the bottom line remains the same — Bush’s own EPA administrator believed the agency was required to do an endangerment finding, and argued that the Clean Air Act could be used responsibly to combat global warming.

Congressional Republicans, in effect, are arguing that the Bush administration’s environmental policies were shaped by radical leftists.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.