The U.S.’s likely absence from the upcoming COP30 is a “watershed moment,” according to EU Climate Commissioner Wopke Hoekstra.

“We’re talking about the largest, the most dominant, most important geopolitical player from the whole world. It is the second-largest emitter,” Hoekstra told Bloomberg in an interview published Sunday.

“So if a player of that magnitude basically says, ‘Well, I’m going to leave and have it all sorted out by the rest of you,’ clearly that does damage,” he added, noting however that some U.S. mayors and governors remained committed to green policies.

The COP30 climate conference will start on Nov. 10 in the Amazon port city of Belém. The Trump administration said it will not send “high level representatives,” amid Washington’s larger push against climate policies.

U.S. President Donald Trump has already announced the U.S. would exit the Paris climate agreement for a second time. Last month, the American delegation to the United Nations International Maritime Organization negotiations in London also pressured countries to skip a vote on a proposed carbon emissions fee on global shipping.

Overall, about 100 countries have failed to submit stronger carbon goals ahead of the COP30, and the EU is lagging behind too. Last year, a U.N. report found that even if nations delivered on their plans for 2030, carbon pollution would fall less than 3 percent compared to 2019 levels. That would likely not be enough to avoid major climate tipping points.

Hoekstra said in the interview that he hopes the COP30 will push governments to “get concrete” about adaptation to the new climate reality and make progress on carbon markets, among other initiatives. The climate commissioner also expressed concerns about China’s push to build coal plants.

“It would be very important for the world if they would actually refrain from that,” he said, adding that Beijing’s commitment to reduce greenhouse gas emissions, known as nationally determined contribution (NDC), is too low.

“Most experts were hoping for an NDC north of 30 percent,” Hoekstra told Bloomberg. “And then an NDC that is in all likelihood below 10 percent? I mean, even with all the diplomatic language I would love to wrap around that, it’s hard to see how that is enough.”