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President Joe Biden speaks during a visit to the Amazon rainforest in Manaus, Brazil, on November 17, 2024.
Rio de Janeiro CNN  — 

When President Joe Biden worked to burnish his climate legacy in the Brazilian Amazon on Sunday, the unspoken presence of Donald Trump shadowed the historic stop.

A sitting American president had never before set foot in the Amazon rainforest, and Biden wanted to use his presence in the vital environment to bring attention to his efforts curbing carbon emissions and helping the world guard against global warming.

Standing on a dirt path with lush palms and other foliage behind him, Biden described the fight against climate change as a “defining” part of his presidency.

But he also warned future administrations that undoing that work would risk depriving the world of its benefits. Without naming President-elect Trump, who has questioned whether climate change exists and vowed to reverse Biden policies on gas and oil exploration, Biden delivered a clear message to the country as he prepares to make way for the incoming Republican president.

“I will leave my successor and my country a strong foundation to build on if they choose to do so. It’s true, some may seek to deny or delay the clean energy revolution that’s underway in America. But nobody, nobody can reverse it. Nobody,” Biden said in remarks from Manaus, Brazil.

“Not when so many people regardless of party or politics are enjoying its benefits. Not when countries around the world are harnessing the clean energy revolution to pull ahead themselves. The question now is: Which government will stand in the way and which will seize the enormous economic opportunity?” he continued.

Before he spoke, Biden viewed dried-up river beds and wildfire damage on an aerial tour of the Amazon rainforest, getting a bird’s-eye view of some of the effects of a yearslong drought.

The half-hour tour aboard Marine One brought Biden to the confluence of the Rio Negro and Amazon rivers, where he saw ships that had been grounded due to low water levels, and over a wildlife preserve.

Among the moves he announced Sunday were tens of millions in US dollars directed toward preserving the Amazon, whose trees act as a sponge for massive amounts of carbon dioxide and which is being threatened by deforestation. And he pledged billions to help nations bolster resilience against climate change.

Saul Loeb/AFP/Getty Images
President Joe Biden, in Marine One, takes part in an aerial tour of the Amazon during his visit to Manaus, Brazil, on November 17, 2024.

But whether any of the money makes it out the door will now largely be up to Trump, who has dismissed climate change — and who, a day before Biden’s trip, named a fracking industry executive as his pick for energy secretary.

Trump has already vowed to withdraw again from the Paris climate accord, which Biden entered back into when he took office four years ago. Trump and his team have pledged to ease restrictions on oil and gas exploration that Biden put in place. And the president-elect has cast a deeply skeptical eye toward foreign assistance of the type Biden announced Sunday.

That dynamic has led to skepticism among world leaders gathered for summits in South America this month that any of Biden’s announcements will last past January, when he exits the world stage.

The stakes of the Amazon’s fate could hardly be higher. Aside from its role absorbing planet-warming gasses, the rainforest accounts for a major portion of the world’s biodiversity and is home to Indigenous populations.