President Joe Biden visited the Brazilian Amazon on Sunday, marking the first time a sitting U.S. president has done so, to highlight his climate change efforts and the importance of protecting the environment.

In Manaus, Biden stressed that climate action is a “defining” part of his presidency, warning future administrations against undoing his policies.

Though he didn’t name President-elect Trump, Biden’s comments were a direct response to Trump’s skepticism on climate change and his plans to reverse Biden’s environmental policies.

Biden announced millions in funding for Amazon preservation and climate resilience, but with Trump’s incoming administration, the future of these efforts remains uncertain, CNN has reported.

The Amazon’s fate is crucial for global biodiversity and combating climate change.

Written by B.C. Begley