President Joe Biden announced another $1 billion in US climate funding Thursday at a virtual meeting with leaders from the world's biggest industrial nations to coordinate efforts to push back on global warming.

The Major Economies Forum on Energy and Climate, which the White House said was attended by officials including Chinese climate envoy Xie Zhenhua and Brazilian President Luiz Inacio Lula da Silva, was the fourth organized by Biden since he became president in 2021.

Biden announced a $1 billion contribution to the Green Climate Fund, which is financing efforts by richer countries to help developing economies switch to cleaner energy and to build climate-resilient infrastructure.

"The impacts of climate change will be felt the most by those who have contributed the least to the problem, including developing nations. As large economies and large emitters, we must step up and support these economies," Biden said.

This money is immediately available, a senior US official told reporters.

However, another $500 million that Biden announced he wants pledged to the Amazon Fund -- financing work to stop commercial deforestation of the planet's biggest rain forest -- faces an uphill battle in securing congressional approval.

Biden put fighting climate change at the top of his agenda when he took office, reversing moves by his predecessor Donald Trump to walk away from US leadership on the issue.

Biden has set a goal of reducing US emissions by 50 to 52 percent by 2030, compared with 2005 levels, as part of the worldwide effort under the Paris climate agreement to limit global temperature increases to 1.5 percent Celsius.

The administration is pushing for far-reaching rules limiting vehicle emissions and it secured a historic spending bill in Congress, the Inflation Reduction Act, to pour billions of dollars into kick-starting electric vehicle and other green technology industries.

"We have to recommit ourselves to action while we still have the time," Biden told the other leaders, who appeared on a large video screen in a White House auditorium. "We have to step up our ambitions."

Calling it a "moment of great peril, but also great possibilities," Biden said the 1.5 Celsius target remains "within reach."

"But it's going to take all of us, not just one of us," he said.