Brazil's new President Luiz Inacio Lula da Silva assumed office on Jan. 1, jump-starting cooperation with the United States on climate change and deforestation after rocky relations under his right-wing predecessor Jair Bolsonaro. Deforestation hit a 15-year high under Bolsonaro, who rolled back environmental protections.

Lula and U.S. President Joe Biden pledged to work together on climate change in a meeting at the White House earlier this month. On deforestation, Washington announced it intended to contribute to Brazil's Amazon Fund, which supports conservation projects in the jungle region.

"The truth is that unless the Amazon is protected from those who would deforest it and who abuse it, we cannot keep the temperature to 1.5 degrees (Celsius)," Kerry said, referring to the climate target in the Paris Agreement.

"The reality is that the Amazon is the test of all of our humanity."

Protecting the Amazon is vital to curbing climate change because of the vast quantity of greenhouse gas its trees absorb.

Appearing alongside Brazil Environment Minister Marina Silva, Kerry told reporters in Brasilia that he traveled to Brazil to work out the details of what Lula and Biden agreed to.

He said that the United States was still considering how much to give to the Amazon Fund.

Kerry said the U.S. Senate is considering a bill with $4.5 billion in funding for forest conservation, while the House of Representatives is studying a proposal with $9 billion.

But, Kerry said the administration "will have to fight" to get those proposals through Congress.

Kerry and Silva said that the United States and Brazil had restarted a bilateral working group set up in 2015 to discuss cooperation on climate and environment, which had stalled under Bolsonaro.

Silva said she discussed with Kerry the possibility of opening up the United States to more sustainable sourced products from Brazil.