John D. Rockefeller built a vast fortune on oil. Now his heirs are abandoning fossil fuels. The family whose legendary wealth flowed from Standard Oil is planning to announce on Monday that its $860 million philanthropic organization, the Rockefeller Brothers Fund, is joining the divestment movement that began a couple years ago on college campuses. In recent years, 180 institutions - including philanthropies, religious organizations, pension funds and local governments ... have pledged to sell assets tied to fossil fuel companies from their portfolios and to invest in cleaner alternatives. In all, the groups have pledged to divest assets worth more than $50 billion from portfolios. Some say they are taking action to align their assets with their environmental principles. Others want to shame companies that they believe are recklessly contributing to a warming planet. Ultimately ... their actions, like those of the anti-apartheid divestment fights of the 1980s, could help spur international debate, while the shift of investment funds to energy alternatives could lead to solutions to the carbon puzzle. At the Rockefeller Brothers Fund, there is no equivocation. The fund has already eliminated investments involved in coal and tar sands entirely while increasing its investment in alternate energy sources. The family has also engaged in shareholder activism with Exxon Mobil, the largest successor to Standard Oil. Members have met privately with the company ... in efforts to get it to moderate its stance on issues pertaining to the environment and climate change. They acknowledged that they have not caused the company to greatly alter its course.