When President Donald Trump withdrew America from the Paris pact, China emerged as the world’s unlikely climate leader. Now ClimateWire reports that China is living up to that role, with plans to establish a nationwide carbon market by November that will be larger than any other in the world.

It’s not yet clear exactly how the market will work. ClimateWire speculates that it might require organizations to buy carbon allowances in order to cover their emissions, or it could be a less stringent regulation that just requires reporting of emissions. But in terms of scale, it will reportedly cover four times the quantity of emissions as a previous carbon market in China, making it the largest ever such scheme on the planet.

It’s not being universally celebrated, though. Critics say that it will cover only 25 percent of the nation’s industrial carbon dioxide and is unlikely to work as well as Western efforts at first—especially ambitious ones like the scheme laid out recently by California. Then there’s the fact that no such market has yet been able to sharply reduce emissions.

Even so, it’s a sign that China takes its de facto climate leadership seriously. And if it sets an example to other Asian nations, that’s definitely no bad thing.