Though only a sliver of the endowment's modest $130 million in assets is invested in fossil fuels, the move is notable because a century ago John D. Rockefeller Sr. made a fortune running Standard Oil, a precursor to Exxon Mobil. The charity said it would also divest from coal and Canadian oil sands.

Given the threat posed to the survival of human and natural ecosystems, "there is no sane rationale for companies to continue to explore for new sources of hydrocarbons," the Rockefeller Family Fund said.

In a letter posted on its website, the fund said Exxon's conduct on climate issues appears to be "morally reprehensible."

Exxon said the Rockefeller fund's move was not surprising.

"The Rockefeller Family Fund provided financial support to InsideClimate News and Columbia University Journalism School which produced inaccurate and deliberately misleading stories about ExxonMobil's history of climate research," Exxon spokesman Alan Jeffers said in a statement.

Stacy Feldman, executive editor of InsideClimate News, stands by those stories.

"Exxon has never specified what is inaccurate or misleading in the series, nor has it requested any corrections," she said in a statement. "But our investigation of Exxon's climate duplicity has won five national journalism awards."

Columbia University officials were not available for comment, but the school has defended its climate work in the past.

Rockefeller Family Fund Director Lee Wasserman said Exxon was not singled out when it granted about $25,000 to InsideClimate News.

"We supported public interest journalism to better understand how the fossil fuel industry was dealing with the reality of climate science internally and publicly," Wasserman said. "No specific company was targeted in our push to drive better public understanding and better climate policy."

Last year, after publication of the stories that Exxon mentioned, New York State Attorney General Eric Schneiderman launched an investigation into whether the company misled the public and shareholders about the risks of climate change.

On Wednesday, Exxon said those stories "wrongly suggested that we had reached definitive conclusions about the risks of climate change decades before the world's experts and while climate science was in an early stage of development."

Exxon said it now believes the threat of climate change is clear and warrants action.

In response to the divestment movement, many oil industry leaders have said millions of people in the developing world would be condemned to darkness and poverty if society were to halt the burning of fossil fuels before there is ample supply of cleaner energy sources.

As early as 2008, members of the Rockefeller family called on Exxon to increase spending on alternative fuels.

In late 2014, another fund associated with the family, the Rockefeller Brothers Fund (RBF), said it would divest from fossil fuels.

(Reporting by Terry Wade and Anna Driver; Editing by David Gregorio and Richard Chang)

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