Trump, who once called global warming a hoax, meets with climate change activist Al Gore

Former vice-president Al Gore, a leading voice in the fight against climate change, and Donald Trump, who at one point called it a hoax, met on Monday in what Gore called a "productive" session.

Gore, a Democrat, spent about 90 minutes in meetings at the president-elect's Trump Tower apartment and office building in Manhattan. In addition to seeing Trump, he also met briefly with the Republican's daughter, Ivanka, who has attended a series of high-level meetings since her father won the Nov. 8 election.

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Gore, who lost the 2000 presidential campaign to Republican George W. Bush, has for years been devoted to lowering carbon emissions blamed for climate change.

As he campaigned for Democratic presidential candidate Hillary Clinton earlier this year, Gore warned that Trump would steer the world toward "climate catastrophe" if elected president.

That warning came amid Trump campaign speeches calling on the United States to drop out of last year's global climate accord signed in Paris to lower carbon emissions.

Trump also referred to human-induced climate change as a hoax, and had tweeted that "the concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive."

Since then, however, in an interview with the New York Times, Trump has indicated that he might have an open mind to joining the effort to battle climate change.

'Sincere search for areas of common ground'

Gore had a somewhat more upbeat take on Trump after huddling with the wealthy New York real estate developer and television reality star.

"It was a sincere search for areas of common ground," Gore told reporters, adding, "I found it an extremely interesting conversation and, to be continued."

Aides to Trump were not immediately available to comment on Monday's meeting.

Gore, who shared the Nobel Peace Prize in 2007 for his work in urging action against the risks of global warming, was also kicking off on Monday a 24-hour talk-a-thon to urge more action in the battle against climate change, which threatens to raise sea levels, spread diseases and increase droughts in more regions in the world.

In a possibly related matter, Trump is scheduled to meet on Tuesday with Rex Tillerson, the head of Exxon Mobil Corp. who possibly is being considered for the job of secretary of state in the Trump administration. Trump takes office on Jan. 20.

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Exxon Mobil has embraced the 2015 Paris Agreement that would lower global greenhouse gas emissions by between 26 per cent and 28 per cent from 2005 levels by 2025.

An aide to Gore said the Trump transition reached out to him after the former vice-president had said he intended to do everything he could to work with the president-elect to ensure that the U.S.remains a leader in the effort to address climate change.