As the Obama Administration set out tough new rules for fuel mileage standards Thursday, getting less attention was the release of the first regulations ever placed on greenhouse gas tailpipe emissions, an effort by the feds to slow the effects of climate change.

"Establishing a harmonized approach to regulating light-duty vehicle GHG (Greenhouse Gas) emissions and fuel economy is critically important, given the interdependent goals of addressing climate change and ensuring energy independence and security," states the report accompanying the new emission rules.

But a closer look at the extensive set of supporting documents released by the feds showed a  repeated reliance on what some charge is a flawed United Nations study on climate change.

At issue is a 2007 report by the Intergovernmental Panel on Climate Change (IPCC), a United Nations organization which shared a Nobel Prize in 2007 with Al Gore for work on global warming. 

The IPCC Fourth Assessment report said the "warming of the climate system is unequivocal," a quote that was repeated in the report on this new tailpipe emission rule.

But in recent months, the release of hacked e-mails associated with what many refer to as "Climategate", has led to the discovery of errors in the IPCC report, which critics say broadly overstated the threats of global warming.

The documents released Thursday bolstering the new rules to limit greenhouse gas emissions by motor vehicles gave only one quick nod to that controversy.

"One commenter suggested that the proposed rule relied too heavily on literature produced by the Intergovernmental Panel on Climate Change (IPCC) and that other peer-reviewed research also should be considered," it said on page 68 of the 660 page Final Environmental Impact Statement from the National Highway Traffic Safety Administration.

If you would like to read that report, you can download it at http://bit.ly/9syVy6 .

The climate change part of these new rules say that NHTSA "has relied extensively" on the IPCC findings, saying it is part of "the most recent, thoroughly peer reviewed, and credible assessments of global and U.S. climate change."

The hundreds of references to the IPCC conclusions should be no surprise, as the Environmental Protection Agency does not hide its support for the findings of the IPCC, devoting a page on the EPA web site to the 2007 IPCC report (http://bit.ly/aFaAyy).

As for these new rules, the feds say the changes will bring about a "small, but quantifiable, reduction in projected global mean surface temperature and sea level" because of reduced carbon dioxide emissions from cars and trucks.

Like the IPCC's findings, statements like that seem likely to draw at least raised eyebrows from those who aren't sold on global warming and climate change in the first place.