Bill Gates on one of the world's biggest problem: cow farts

Microsoft co-founder Bill Gates tells CNN's Fareed Zakaria that bovine flatulence is a large contributor to global warming and no one knows exactly how to limit gas emissions generated by livestock: "So the animals that can eat grass have very unusual stomachs that have these bacteria that are methanogenic in there. And so they leak natural gas both out he front and the back. And so people have said, well, let's change the hay or throw some things in there. And it's been, nobody knows how to get rid of that...But that's another big source of greenhouse gas emissions...If it was a 50% reduction, then you could ignore, okay, leave the cows alone. But because we're trying to avoid the temperature continuing to go up, you do need to go to zero. Otherwise you're continuing to have temperature increase."