(UPDATE 2/10: For another take on the issue, check out this item posted on Grist from the Natural Resources Defense Council.)

Enemies of the Environmental Protection Agency are rallying today in Congress, but they may find their efforts blunted by an act of environmental weakness by Stephen L. Johnson, a former EPA administrator under President George W. Bush.

In 2008, we called for Johnson to resign because of his well-publicized attempts to gut the EPA’s mission of protecting the environment. But, as we are just now learning, the EPA’s mission was compromised more by what Johnson didn’t do.

The evidence, in the form of a private letter by Johnson to Bush, was revealed last night just before today’s hearing in Congress on whether the EPA should regulate greenhouse gases. Ironically, the letter is being used in defense of the EPA.

Johnson’s letter to Bush in 2008 asserted that climate change and its impacts on human health were indisputable scientific facts. Bound by a Supreme Court decision, Johnson told his boss that an “endangerment finding” had to be issued by the EPA, declaring greenhouse gas emissions to be a public health hazard. As quoted today by the New York Times, Johnson was unequivocal:

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…The state of the latest climate change science does not permit a negative finding, nor does it permit a credible finding that we need to wait for more research.

According to Politico, Johnson even had a plan of action to deal with emissions sources. But, when Bush operatives like Dick Cheney discovered what Johnson was up to, they stepped in and convinced Johnson to choose between scientific facts and political facts of life.

Johnson eventually overruled his own scientists and publicly announced that the EPA would wait for more evidence to emerge. It took a new administration and a new EPA administrator to do what Johnson himself knew was proper and legal. In 2009, EPA Administrator Lisa Jackson officially decreed an endangerment finding for carbon dioxide and other greenhouse gases, setting the stage for a showdown in Congress over EPA’s power to regulate the sources of greenhouse emissions.

Johnson’s letter was revealed yesterday by House Energy and Commerce Committee ranking member Henry Waxman (D-Calif.) in advance of today’s committee hearing on the endangerment finding. The hearing deals with a bill by committee Chairman Fred Upton (R-Mich.) that would remove the endangerment finding and prevent the EPA from regulating greehouse gases.