The outgoing Barack Obama administration announced Tuesday a contribution of half a billion dollars to the UN Green Climate Fund, just three days before Donald Trump takes over the White House.

The $500 million payment, announced by State Department spokesman John Kirby in a statement, is the second from the United States to support the United Nations Green Climate Fund, which aims to mitigate the effects of climate change in the world's poorest countries.

The Paris accord reached in late 2015 has been dubbed one of Obama's successes -- whereas the Republican president-elect has called climate change a "hoax."

The Obama administration had announced in 2014 -- a year before the COP 21 agreement was adopted -- a $3-billion pledge for the fund.

Trump said during his campaign that global warming was a hoax invented by the Chinese, and vowed to ditch US commitments to cut down greenhouse gas emissions.

Rex Tillerson, former ExxonMobil chief and the president-elect's nominee for secretary of state, said last week that he wants the US to keep "a seat at the table" regarding global warming.

"No one country is going to solve this alone," he said at his Senate confirmation hearing.

"The risk of climate change does exist, and the consequences could be serious enough the action should be taken."

Trump had threatened to cancel the Paris Agreement -- a global accord on curbing greenhouse gas emissions -- but after being elected he dialed back that promise, saying he had an "open mind" about it.