A surprise agreement at the COP26 climate summit between the world’s two largest economies could help curb major sources of a super-heating greenhouse gas.

China and the U.S. vowed to work together to slow global warming at COP26 in Glasgow.

China and the U.S. vowed to work together to slow global warming at the conference in Glasgow, focusing among other things on tackling methane emissions, a major component of natural gas that traps more than 80 times more heat than carbon dioxide in its first two decades in the atmosphere. 

China is the largest methane emitter, ahead of Russia and the U.S., according to the Global Methane Initiative, which based its calculations on U.S. Environmental Protection Agency data. Beijing signaled earlier it wouldn’t join a global pledge to tackle the issue, saying it didn’t offer concrete solutions.

Last week, when asked why the country hasn’t joined the global methane pact, China’s Ministry of Foreign Affairs spokesman Wang Wenbin said that it “attaches high importance to the control of non-carbon dioxide greenhouse gases” and that it “is ready to work with other parties to advance global cooperation” on reducing them.

China’s methane emissions from coal mining activities dwarf those of other producers, while the U.S. contributes the second-most from oil and gas operations behind Russia, according to estimates from the International Energy Agency. Combined, the countries’ energy sectors spew 40 million tons of methane, which heats the atmosphere more in the near term than all the carbon dioxide released by burning fossil fuels in the European Union.

The good news is that it’s a problem with cost-effective solutions. Cheap technologies to mitigate coal mine emissions are widely available, according to climate research group Ember, while oil and gas companies can often profit from emissions reductions by selling the corralled methane as natural gas.

“Tackling methane emissions from fossil fuel operations represents one of the best near-term opportunities for limiting the worse effects of climate change,” the IEA said in an October report.