U.N. officials say methane emissions are still going up, but they have hope that cutting them in coming years could have big implications for slowing Earth’s warming. Methane traps significantly more heat than carbon dioxide, but it leaves the atmosphere much faster. That means effective action to reduce it could have a quick payoff. Martina Otto, head of the U.N.’s climate and clean air commission, describes methane as a potential “hand brake” for controlling greenhouse gases. Methane emissions are projected to drop by 8% by 2030 if countries follow their climate plans. But the goal is a 30% reduction.