Former New York mayor and billionaire Michael Bloomberg says he will write a $US4.5 million ($A5.8 million) cheque to cover this year's US financial commitment to the Paris Climate Agreement.
President Donald Trump last year pulled the United States out of the pact, making the country the only one opposed to it.
Bloomberg, in a CBS interview on Sunday, said he hopes by next year Trump will have changed his mind.
Bloomberg will continue to provide money for the pact if the US does not rejoin the agreement, according to a news release from Bloomberg Philanthropies, the charity he founded.
"Our foundation will uphold our promise to cover any cuts to UN climate funding by the federal government," Bloomberg said in the statement.
Trump staunchly opposes the agreement and his administration has rolled back a number of environmental regulations.
