President Joe Biden said the sole threat to humanity’s existence is climate change, and that not even nuclear conflict poses a similar danger.

“The only existential threat humanity faces, even things more frightening than a nuclear war, is global warming,” Biden said Sunday during a news conference in Hanoi, Vietnam.

The president added “we’re going to be in real trouble” if, in the next decade or two, warming goes above the 1.5C temperature increase that scientists consider a tipping point for increasing the chances of extreme weather events.

“There’s no way back from that,” Biden continued. “And so there’s a lot we can do in the meantime.”

Biden spoke following the Group of 20 summit in India, where leaders agreed to a series of climate actions, including a pledge to triple renewable energy capacity by the end of the decade.

The president’s attention this year has been consumed at times by weather and climate disasters, including deadly wildfires in Maui. The US has suffered more than a dozen billion-dollar severe weather events this year, according to the National Centers for Environmental Information.

Still, world events, especially the war in Ukraine, have continued to prompt fears of a potential nuclear conflict. Russian President Vladimir Putin has threatened to unleash his country’s nuclear arsenal should its sovereignty be violated, and he recently positioned nuclear assets in neighboring Belarus.

“When I was out here about three years ago saying I worried about the Colorado River drying up, everybody looked at me like I was crazy,” Biden told campaign donors at a June fundraiser. “They looked at me like when I said I worried about Putin using tactical nuclear weapons. It’s real.”

--With assistance from Justin Sink.