Last week, a coalition of 44 investors with $546 billion in assets under management wrote to the leaders of the U.S. Senate, urging them "to allow the U.S. Environmental Protection Agency (EPA) to move forward with its greenhouse gas (GHG) regulations and to oppose any constraints on EPA's authority to do so."

The letter comes at a time when one of its recipients, Republican Senator Mitch McConnell of Kentucky, has introduced an amendment to a small business bill that would strip EPA of its authority to regulate GHG emissions, despite a 2007 Supreme Court ruling that explicitly authorized EPA to do so under the Clean Air Act.

Citing its authority under the Clean Air Act, EPA established regulations that require large facilities emitting more than 25,000 tons of GHG emissions a year to obtain permits demonstrating that they are using the best practices and technologies to minimize GHG emissions. The rules took force in January.

In 2009, when she originally announced the proposed rules, EPA Administrator Lisa Jackson said, "We are not going to continue with business as usual while we wait for Congress to act. We have the tools and the technologies to move forward today, and we are using them." However, the U.S. Chamber of Commerce responded by filing a lawsuit challenging the authority of the EPA to regulate GHG emissions.

And last week, the National Association of Manufacturers (NAM) sent letters to U.S. Senators, claiming that "the McConnell Energy Tax Prevention amendment ... would stop EPA regulations that are costing jobs and hurting our nation's economic recovery."

In their letter, the investors wrote, "As investors we prefer long-term certainty on energy and climate policy to be able to predict investment risks and opportunities ... inconsistent and volatile clean energy and climate policies have already resulted in capital moving overseas and job loss in the United States."

"Congress should take the lead in addressing climate change by passing comprehensive climate and energy legislation," the investors wrote. "However, in the absence of such legislation in the foreseeable future, EPA must be allowed to move forward using its existing authority."

The letter advises investors wishing to join the coalition to contact Stu Dalheim, the Director of Shareholder Advocacy at Calvert.

This article originally appeared at SocialFunds.com and is reprinted with permission.

Image CC licensed by Flickr user o palsson.