Leading philanthropists pledged hundreds of millions of dollars to rescue shrinking tropical forests that suck heat-trapping carbon dioxide from the atmosphere, on the eve of a global climate change summit in San Francisco.

Nine foundations announced the $459 million commitment, to be delivered over the next four years, a day ahead of the Global Climate Action Summit, which is expected to draw about 4,500 delegates from city and regional governments.

“While the world heats up, many of our governments have been slow – slow to act. And so we in philanthropy must step up,” Darren Walker, president of the Ford Foundation, told journalists at an event announcing the pledge.

The commitment roughly doubles the funds the groups currently dedicate to forest protection, said David Kaimowitz, a director at the Ford Foundation, one of the donors.

Charlotte Streck, director of Amsterdam-based think tank Climate Focus, said the size of the commitment makes the groups major players in supporting anti-deforestation programs.

Norway has led donor efforts by pledging up to $500 million a year to help tropical nations protect their forests, Streck said.

But the new money committed by foundations could prove more “flexible and nimble” than money from governments, she said.

“The money that has been pledged by the governments like Norway and Germany, the UK, sits mostly in trust funds with the World Bank and the UN and it doesn’t get out so quickly,” she said.

Often “there is $20,000 missing here or $50,000 missing here, just to do one thing or develop one study or work with one person or have one consultation – and that the foundations can do”, Streck said.

Other groups that are part of the new initiative include the MacArthur Foundation and The Rockefeller Foundation.

Funds will mostly assist indigenous people who are forest dwellers, including by helping them secure titles to land they live on so it cannot be sold to private companies without their agreement, said Walker.

“Companies come to our village, our forests and say: ‘You have to leave because I have the license from the government’,” said Rukka Sombolinggi, who heads the Indonesia-based Indigenous People’s Alliance of the Archipelago (AMAN).

The world loses the equivalent of 50 soccer fields’ worth of forest every minute, organizers said.

Yet forests absorb a third of the annual planet-warming greenhouse gas emissions produced – and those emissions need to be slashed substantially more to meet the goals set in the Paris agreement.

The Paris climate agreement, adopted by almost 200 nations in 2015, set a goal of limiting warming to “well below” a rise of 2 degrees Celsius (3.6°F) above pre-industrial times while “pursuing efforts” for the tougher goal of 1.5 degrees C.

The three-day Global Climate Action Summit was organized by Californian authorities and the United Nations to support the leadership of mayors, governors and other sub-national authorities in curbing climate change.

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