Joe Biden became the first sitting US president to visit the Amazon rainforest on Sunday, as his successor Donald Trump vowed to scrap measures to fight climate change.

Biden traveled from Peru, where he attended his last summit with Asia-Pacific leaders, to the city of Manaus, in Brazil, in the heart of the world's largest jungle.

The Amazon, which is about the size of Australia, stores huge amounts of the world's carbon dioxide, a greenhouse gas that drives climate change when released into the atmosphere. But the rainforest is also vulnerable to environmental degradation that could exacerbate climate change.

What's on Biden's agenda during the Amazon trip?

The 81-year-old Biden flew over the rainforest by helicopter and was due to visit a museum before meeting with Indigenous and local leaders working to preserve the Amazon.

The president's tour included views of the shallowing of Amazon waterways as a result of a two-year drought and inspecting damage from large-scale wildfires and deforestation. He was also due to visit a wildlife refuge.

Biden was joined by Carlos Nobre, a Nobel-Prize-winning scientist and expert on how climate change is impacting the Amazon. He was accompanied by White House climate adviser John Podesta.

Ahead of the visit, the White House said Washington had hit its target of boosting bilateral climate financing to $11 billion (€10.44 billion) a year. The amount was six times what the US was providing at the start of Biden's term, in 2021, but still behind the funds provided by the EU.

Biden promised last year to boost the Brazilian-administered Amazon Fund by $500 million, but Washington has so far delivered on just a tenth of the amount committed. On Sunday, the White House confirmed a second $50 million payment was on track.

After his stop in Manaus, Biden will head to Rio de Janeiro for this year's G20 (Group of 20) leaders' summit, which begins Monday. Climate change will be one of the priorities at the talks, along with Brazil's plan for a new tax on the world's richest billionaires, which will help fund climate and poverty alleviation goals.

What is Brazil doing to stop Amazon deforestation?

A recent study showed that the Amazon has lost an area about the size of Germany and France combined to deforestation in four decades.

In the 12 months to July, some 6,288 square kilometers (2,428 square miles) of forest was lost, as a result of  drought, wildfires and land clearing.

Brazilian President Luiz Inacio Lula da Silva has vowed to end deforestation by 2030.

His predecessor, the far-right Jair Bolsonaro prioritized agricultural expansion over forest protection, helping deforestation to surge to a 15-year-high.

The Amazon is unlikely to get much new support from Donald Trump's second term in the White House. The Republican politician has already called climate change a hoax.

The president-elect has also vowed to pull the US — the world's second-largest polluter —  out of the Paris climate agreement for a second time.

He has announced plans to boost US oil and gas production and do away with subsidies to help wean US drivers onto electric vehicles.

On Saturday, Trump nominated fracking magnate and noted climate change skeptic Chris Wright as his energy secretary.

mm/dj (AFP, AP, Reuters)