"Cutting methane is the single fastest, most effective opportunity to reduce climate change risks in the near term," says atmospheric scientist Ilissa Ocko. That's because, unlike carbon dioxide, methane's warming power doesn't come from a gradual buildup over time but is almost entirely from recent emissions. Ocko identifies three main sources of methane pollution which, if addressed, could dramatically slow down the rate of global warming within years -- not decades. "This is the methane moment," Ocko says.