Environmentalists from across the world are pressuring philanthropic foundations that help fund climate change projects to drop their investments in fossil fuels.

The environmentalists, all of whom have won major environmental honors, say they are targeting the foundations that handle billions of dollars in funding for climate change projects because those organizations likely are unaware that some of their finances are tied up in fossil fuels, which most scientists blame for causing global warming.

“The escalating climate crisis threatens the programs of every philanthropic organization," said Ellen Dorsey, executive director of the Wallace Global Fund and leader of the coalition calling for divestment. "Growing numbers of foundations are shifting their money from fossil fuels to clean energy so their investments help solve this crisis instead of contributing to it. We hope that our stand will encourage others to take the urgent action we now need to prevent runaway global warming.”

Spearheaded by the European Environment Foundation, the call from more than 160 environmental activists spanning 44 countries dovetails with a broader push aimed at universities, pensions and other endowments. The activists say fossil fuels need to stay in the ground if the world is to avoid some of the most catastrophic effects of climate change.

The financial logic behind the divestment strategy is that, as the effects of climate change become more pervasive, policymakers will enact measures to make burning the fossil fuels that warm the planet more costly. As such, the potential return on investment in fossil fuels would become risky.

It's a catch-22. If philanthropies turn away from fossil fuel investments that have provided stable returns for their efforts, they might not have the same amount of money to dish out in the future if a shift toward alternatives proves less profitable.

Instead, some investors are more realistic. A wholesale shift away from fossil fuels won't happen overnight, said Mindy Lubber, president of business sustainability group Ceres. Such investments are still fairly low risk, all things considered.

"Venture capitalists are saying that the play right now is renewable energy, electric vehicles," Lubber told the Washington Examiner. "But obviously not everything is black and white. Nobody is talking about taking all of their investments in fossil fuels tonight and investing in electric vehicles tomorrow."

Still, activists say their divestment push has notched some recent gains, especially among universities — Stanford being one of the higher-profile names to divest. Getting pension funds, which control billions of dollars in investments, to move away from fossil fuels has proven more difficult, though the University of California school system is weighing that option.

The effort comes as activists are gearing up for what they say will be the largest climate demonstration on record on Sept. 21 in New York. The " People's Climate March" is timed to coincide with the United Nations climate summit being held there Sept. 23. The summit is a prelude to international climate negotiations next year in Paris, where nations will seek commitments to cut enough emissions by 2020 to avert a 2 degrees Celsius temperature rise by 2100.

Targeting philanthropic foundations whose stock-in-trade include wealthy, liberal donors seems like low-hanging fruit.

"If your funder is ... [conservative casino magnate Sheldon] Adelson — if those are your funders, yeah, you have to keep those guys happy," said an environmental strategist. "But most of these guys, their funding is coming from a more diverse [group] ... or from lefties."

But if activists can get like-minded foundations to change, that would represent a significant development even from two years ago, when dropping investments in fossil fuels that have netted steady returns for decades was virtually unthinkable.

Some financial instruments are evolving to reflect growing interest in such investments. Morgan Stanley, for example, created its Institute for Sustainable Investing last year in response to client demand. The amount spent on "green" bonds — which support clean energy projects — has grown from $2 billion in 2012 to $20 billion already issued in 2014.

Still, there's a shortage of options, said James Arbib, founder and trustee of the Tellus Mater Foundation.

"One of the key barriers we need to overcome is the lack of sophisticated products and the associated financial infrastructure to allow us to invest in this way. We are keen to work with other foundations and long-term investors, and the financial community to help develop this emerging market," Arbib said.

Ultimately, Lubber said, it's about setting a price on carbon to better reflect the cost of damages from burning fossil fuels. In the meantime, her group and others are working with companies to set greenhouse gas-emitting and renewable energy goals. Sixty percent of Fortune 100 companies have them so far.

Still, most companies' climate targets are often less ambitious than what climate models suggest is necessary, said Jennifer Morgan, climate and energy director with the World Resources Institute.

The emergence of high-performing energy investment alternatives to fossil fuels will hopefully change that, Lubber said. She called it a marked improvement in and of itself in recent years, and said it's a harbinger of more to come.

"Risk drives investment markets, as it absolutely should," Lubber said. "But the other thing that drives the economy and this country is opportunity."