Given total Republican obstructionism in Congress, President Obama’s climate legacy will depend mostly on executive action. But new developments on the corn ethanol front could pave the way for a the rarest of Washington beasts: a bipartisan compromise on an issue that could have a real impact on climate change.

On the climate and environmental side, corn ethanol is turning out to be worse than anyone imagined. On the conservative side, corn ethanol only survives due to a government mandate that it be included in American fuels — the stuff of free market nightmares.

Today, the Environmental Protection Aagency is expected to release its latest ethanol inclusion mandate, which for the first time would reduce its size. This is a good first step, but it’s high time Congress acted to kill the mandate altogether.

Environmentalists have always been rather skeptical about corn ethanol in general. Under ideal conditions, it provides a slight climate advantage over gasoline, but with only a small departure from best practices, that advantage evaporates. Corn needs fertilizer, and ethanol factories need energy, both of which typically come from natural gas. Finally, an ethanol mandate would increase the price of corn, which could spark new planting of corn in previously undisturbed areas, a process which releases huge amounts of greenhouse gases.

It’s been clear for some time now that corn ethanol was not living up to its promises. But a recent blockbuster report from AP makes crystal clear that all the skeptics were right. Not only are the theoretical benefits smaller than predicted, the price of corn has skyrocketed (also due in part to commodity speculators). The feared massive new planting has indeed happened, and much of it on marginal land that is eroding fast and washing millions of tons of toxic fertilizer into nearby waterways. Compounding everything, this is all happening during a prolonged and terrible drought, sharply increasing the amount of land dedicated to fuel at a time of food scarcity.

The mandate was supposed to spark the development of cleaner biofuels (like “cellulosic” ethanol), which are compelling in theory. But it’s been six years with no result, and the current situation is doing so much damage that it’s time to just cut our losses. Besides, a thriving biofuels industry already exists in the form of Brazilian sugarcane ethanol, which is unambiguously a big win on climate change. Biofuels research will continue, especially if the EPA manages new regulation on carbon dioxide.

Typically, Republicans are complete hypocrites when it comes to farm policy, showing no compunction about passing a bloated socialist monstrosity of a farm bill time after time, or even personally collecting huge government subsidies. But the ethanol mandate is so wretched on free-market terms (and as an added bonus, it’s connected to the hated EPA) that even Republicans might be convinced it’s worth patching. President Obama should be open to the possibility, so long as the change is narrowly targeted to the mandate alone.

Of course, even if the corn ethanol mandate were killed, it would amount to a tiny fraction of what’s needed to combat climate change. The fact that bipartisan compromise is imaginable on such a miniscule portion of what needs to be done is a reminder of how far away we are from having a Congress that’s functional enough to begin dealing with the greatest problem humanity faces.

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