The Environmental Protection Agency is rapidly laying the groundwork for regulation of greenhouse-gas emissions, upping the pressure on Congress to pass a climate bill and beat the Obama administration to the punch.

On Tuesday, the agency unveiled a plan that would require some 13,000 major polluters to report their emissions, creating the first comprehensive national inventory of greenhouse gases.

Also on Tuesday, an EPA document leaked to the press indicated that the agency plans by mid-April to issue a finding on whether global warming poses a danger to humankind, which would likely trigger regulation of greenhouse gases under the Clean Air Act.

The emissions reporting system would help guide policy making by providing detailed data about where emissions are originating. The government issues a report each year documenting the country’s total emissions by sector (the latest one came out last week), but this new system would go beyond that, breaking down emissions by facility.

Emissions reports would be required from large industrial facilities that emit 25,000 metric tons per year or more — including electric utilities, oil and chemical refineries, automobile and engine manufacturers, iron and steel producers, and concentrated animal feeding operations — but small businesses would be exempt. Most sectors would have to report on their 2010 emissions by 2011, while vehicle and engine manufacturers would begin reporting for the 2011 model year.

“Our efforts to confront climate change must be guided by the best possible information,” said EPA Administrator Lisa Jackson in a statement. “Through this new reporting, we will have comprehensive and accurate data about the production of greenhouse gases.”

Legislators who will play a key role in shaping climate policy praised the move. “A reliable accounting of carbon emissions is the first important step in any program to address global warming,” said Sen. Barbara Boxer (D-Calif.), chair of the Environment and Public Works Committee.

Rep. Ed Markey (D-Mass.), chair of the House Energy and Environment Subcommittee, noted that the inventory will help the U.S. avoid the pitfalls encountered in the European Union, where flawed emission-level estimates undermined its cap-and-trade program. “We must learn from the E.U.’s mistakes in moving forward our clean energy policies,” said Markey. “Accurate and timely reportage of U.S. global warming emissions is crucial to the successful implementation of climate legislation.”

Congress directed the EPA to craft an emissions reporting system in a 2007 bill, but the Bush administration stalled and never acted on the directive.

The Bush admin also failed to move forward on an assessment of the dangers posed to humans by greenhouse-gas emissions, though the Supreme Court directed it to produce one in an April 2007 ruling.

The Obama administration is now pushing ahead on both matters — so quickly that even some environmentalists are surprised.

According to the leaked document [PDF], EPA staffers expect to have internal deliberations on an assessment of climate dangers completed by March 18. Then the White House Office of Management and Budget would lead a three-week inter-agency review, after which Jackson would sign the finding on April 16. There would then follow a 60-day public comment period and two public hearings before the rule is finalized.

If, as expected, the EPA finds that greenhouse gases pose a significant danger to humans, then the agency would have to start the process of figuring out how to regulate them under the Clean Air Act. In her confirmation hearing in January, Jackson acknowledged that such a finding would “trigger the beginnings of regulation of CO2 for this country.”

But many interested parties on all sides of the issue would prefer that a regulatory framework come from Congress rather than the executive branch. In the end, the biggest effect of Tuesday’s developments may be to increase pressure on Congress to move on a climate bill — fast.