Secretary of Defense Lloyd Austin on Thursday described the climate crisis as one of the nation’s existential threats with the potential to profoundly destabilize global security.

“From coast to coast and across the world, the climate crisis has caused substantial damage and put people in danger, making it more difficult for us to carry out our mission of defending the United States and our allies,” Austin said in an address at a summit with world leaders focused on climate change.

“As the Arctic melts, competition for resources and influence in the region increases. Closer to the equator, rising temperatures and more frequent and intense extreme weather events in Africa and Central America threaten millions with drought, hunger and displacement,” the Pentagon chief added.

President Joe Biden kicked off the virtual summit, which falls on the fifth anniversary of the Paris Agreement signing and Earth Day, with a pledge to cut emissions by 50% to 52% by 2030.

The new target more than doubles the Obama administration’s prior commitment under the 2015 Paris climate agreement. Former President Donald Trump withdrew the United States from the accords in 2019.

“I welcome President Biden’s leadership on tackling climate change,” NATO Secretary-General Jens Stoltenberg said in his opening remarks at the summit.

“Global warming is making the world more dangerous. It has a serious impact on our security, so it matters for NATO,” he said, adding that NATO members would be stepping up efforts to address the climate crisis.