Congressional Carbon Credits:

Last year the U.S. House of Representatives purchased carbon offsets in an effort to make the legislative body "carbon neutral." Yet as the Washington Post reports, it is not clear the purchases did much of anything to offset Congressional emissions.

In November, the Democratic-led House spent about $89,000 on so-called carbon offsets. This purchase was supposed to cancel out greenhouse-gas emissions from House buildings -- including half of the U.S. Capitol -- by triggering an equal reduction in emissions elsewhere.

Some of the money went to farmers in North Dakota, for tilling practices that keep carbon buried in the soil. But some farmers were already doing this, for other reasons, before the House paid a cent.

Other funds went to Iowa, where a power plant had been temporarily rejiggered to burn more cleanly. But that test project had ended more than a year before the money arrived. . . .

The House bought its offsets through the Chicago Climate Exchange, a five-year-old commodities market where greenhouse-gas credits are traded like pork bellies.

This month, officials at the exchange vigorously defended the sale, saying the House's purchase had done a great deal of good by funneling money to those who were helping to combat climate change.

"It basically rewards people for having done things that had environmental good in the past and incentivizes people to do things that have environmental good in the future," said Richard Sandor, the exchange's chairman and chief executive.

He rejected the argument that the exchange shouldn't sell offsets until it can prove that the pollution reductions wouldn't have happened if the money wasn't paid. "We can't, as an exchange, trade hypothetical things," Sandor said.

There is a silver lining to the story, however. Apparently the House purchased the credits in a way to prevent interference from earmark-happy legislators.

Daniel P. Beard, the House's chief administrative officer, said he asked the Chicago exchange for offsets based only on U.S. projects. But, he said, he asked not to be told where the projects were, so representatives could not buttonhole him about projects in their districts.

At least that's something.