In the latest cover story for Rolling Stone, economist and New York Times columnist Paul Krugman offers a full-throated defense of the Obama administration, taking to task its critics from across the political spectrum. Included in the typically dour liberal’s praise: the president’s environmental policy, which "is starting to look like it could be a major legacy."

“We'll have to do a lot more soon, or face civilization-threatening disaster,” Krugman writes. “But what Obama has done is far from trivial.”

He ought not to give the White House so much credit.

Any rigorous measure of environmental policy has to consider the scope of the global climate crisis. If the planet is to avoid a two degree Celsius rise above pre-industrial levels—the internationally recognized threshold that, if surpassed, will unleash the most nightmarish effects of climate change—then we need to start leaving carbon in the ground, right now. (Activist and writer Bill McKibben has calculated about four-fifths of the world’s known fossil fuel reserves must stay in the soil.) Given that math, the least we might ask of an American administration is not to exploit the reserves that happen to fall within U.S. borders. We might also ask that federal policy encourage a faster transition to renewable energy sources like wind and solar.

On both counts, the administration has failed.