Cow farts-and the contributions of the methane therein to climate change-have long been a favorite bogeyman for critics of the cattle industry. (Their burps are a bigger problem, in fact, but who's counting when it comes to cow effluvia?) What no one thought to ask until now is, why are the cows burping so much? The answer, unsurprisingly, turns out to be their diets. When cows are fed plants like alfalfa-plants more closely related to the grass they would naturally eat-their emissions are reduced by as much as 30 percent. Cow burps may make up less than 2 percent of U.S. emissions, but this easy fix for an iconic problem shows that sometimes a simple solution is right under our noses.