President Biden pledged new financial help to protect the Amazon, the planet’s largest tropical rainforest, during a visit to Brazil on Sunday, making one final push to combat climate change before President-elect Donald J. Trump returns to power in January.

After an aerial tour of one of the world’s most diverse ecosystems, Mr. Biden signed a proclamation declaring every Nov. 17 to be International Conservation Day and vowed that the United States would spend millions of dollars across the Amazon on restoring land, planting native tree species, supporting biodiversity efforts and increasing fertilizer efficiency programs. It was the first time a sitting American president had visited the Amazon.

“It’s often said that the Amazon is the lungs of the world,” Mr. Biden said during a brief stop in Manaus, a bustling city of two million nestled in the heart of the rainforest. "But in my view, our forest and national wonders are the heart and soul of the world,” he added. “The Amazon rainforest was built up over 15 million years. Fifteen million years history is literally watching us now.”

Flying low in his Marine One helicopter across the vast canopy of trees, Mr. Biden traveled along the Rio Negro, where its dark waters met the murky brown of the main Amazon River. From his helicopter, the president could see a wildlife refuge, shore erosion, fire damage and grounded ships, according to a map of the area provided by the White House.

But his initiatives may be short-lived. Environmental activists are bracing for a drastic shake-up in U.S. foreign policy under Mr. Trump, who has loudly opposed international cooperation on climate change. He has vowed to abandon global commitments and undo many of Mr. Biden’s environmental pledges.

Mr. Trump has said he will withdraw the United States — for a second time — from the landmark Paris climate accord, which aims to curb planet-warming emissions and rein in rising temperatures. He has promised to “drill, drill, drill” for oil and gas and nominated Chris Wright, a fossil fuels executive who has claimed “there is no climate crisis,” to lead the Department of Energy.

We are having trouble retrieving the article content.

Please enable JavaScript in your browser settings.

Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.

Thank you for your patience while we verify access.

Already a subscriber? Log in.

Want all of The Times? Subscribe.lucky sprite

• lucky sprite
• Biden
• Amazon
• Visits
• Vowing