Students fighting climate change have been trying to pressure universities to divest from the fossil fuel industry for years: They have shouted slogans, marched, rallied, waved signs. They have signed petitions and passed resolutions and referendums. They have disrupted Zooms and football games and board meetings and administration buildings. They have covered themselves in oil.

Now, frustrated by the response from some school officials, a coalition of student groups working with the nonprofit Climate Defense Project has escalated the fight. Instead of just trying to convince university leaders that their investments are immoral for contributing to global warning, the groups argue that the investments are also illegal.

Student-led campaigns at Yale, Princeton, Stanford and Vanderbilt universities and the Massachusetts Institute of Technology filed complaints Wednesday with their respective state attorneys general in a bid to compel schools to divest. The campaigns have requested an investigation into whether the schools have violated a state law related to investments by nonprofit institutions.

The complaints argue that the Uniform Prudent Management of Institutional Funds Act requires universities to ensure their resources are put to socially beneficial ends, and that putting money into fossil fuel companies is in direct conflict with their missions. They also argue that the investments may no longer make financial sense, with the complaints saying “oil and gas stocks have greatly underperformed other investments over the last ten years.”

The complaints estimate the total amount — often hundreds of millions of dollars — they believe to be invested in fossil fuels such as coal, oil and natural gas at each institution.

Several students said it’s hard to watch the deliberation and caution of university leaders in the face of the urgency of the climate crisis for their generation.

“We’re doing something that will be much harder to ignore here,” said Peter Scott, a junior at MIT who is a co-leader of MIT Divest. “That’s what we’re excited about.”

Many university leaders have long resisted calls to divest, pointing to the imperative to invest their endowments wisely and the historical strength of the fossil fuel industry. They also argue that the funds should not be used as political instruments.

But schools — including some targeted in the new legal complaints — have also taken steps to reduce investments in the industry.

When Harvard University announced in the fall that it would end all of its investments in fossil fuels, the move was seen by many as a watershed.

The endowments of the five schools targeted in the new complaints amount to more than $150 billion in total.

Some of the institutions’ investment strategies are widely admired for their financial success: Yale’s endowment boasted an $11 billion increase in the 2021 fiscal year, with a rate of return that topped 40 percent, the university announced last fall.

But for some students, those returns are troubling. It’s crazy, said Molly Weiner, 19, an organizer with Yale Endowment Justice Coalition who is from California, that the university is making big returns off investments that include fossil fuel funds. “I’m here studying environmental policy, yet my school is contributing to the climate crisis,” she said. “It’s really awful.”

Last June, Yale announced steps toward divestment, including principles for investing in fossil fuels and listing companies no longer eligible for investment. Those follow efforts started in 2014 to keep consideration of climate change “essential” when making investment decisions. But students are pushing for complete divestment from all fossil fuels.

The complaints filed Wednesday point to environmental disasters they attribute to climate change such as flooding and wildfires. In some cases, they point to potential conflicts of interest among university leaders.

Princeton announced last May that it had begun the process of “dissociating from companies engaged in climate disinformation campaigns or that are involved in the thermal coal and tar sands segments of the fossil fuel industry,” among other steps.

Officials from the MIT Investment Management Co. explained on their website that while 15 years ago they actively sought out fossil-fuel investments, they have dramatically reduced their exposure and begun to identify ways to move the portfolio to net carbon-neutral over time.

Many universities are also working on other initiatives to combat climate change, from research efforts to reducing their own carbon emissions. Stanford completed a year-long review of fossil fuel investments in 2020 and committed to accelerating its transition to net-zero greenhouse gas emissions.

Stanford spokeswoman Dee Mostofi said the university is confident that Stanford investments fully comply with all applicable laws regulating charities in California.

The joint actions filed Wednesday follow similar recent legal efforts at Cornell, Harvard, Johns Hopkins and Marquette universities, Boston College, the University of Wisconsin and the University of New Mexico.

Ted Hamilton, co-founder and staff attorney with the nonprofit Climate Defense Project, said activists are not pushing universities toward a fringe position in advocating for divestment. “We’re making a common-sense claim that lots of universities have already come to.” The University of California, Georgetown University and others have pledged to divest from fossil fuels.

But Steven Bloom, assistant vice president for government relations with the American Council on Education, which represents college presidents, said he thinks the legal effort is unlikely to succeed.

Universities are taking many steps to move toward carbon neutrality, he said, but such institutions are conservative in managing their endowments, “as they should be.” The funds are intended not only for the needs of the present but for the long term, he said. “It seems like a stretch, if you look at the law itself, that they have failed to act in ways consistent with their legal requirements,” he said.

Activists frustrated that their concerns about climate change haven’t been adequately addressed by national or global policies are looking for other ways to effect change, said Tom Sanzillo, director of financial analysis for the Institute for Energy Economics and Financial Analysis, a nonprofit group advocating for energy transition. And the dynamics have changed completely in the past several years, he said. One reason is financial: In the 1980s, the fossil-fuel sector of the economy was 28 percent of the stock market, he said. “Now it’s 3.”

Bethany Williams, a spokeswoman for the American Petroleum Institute, wrote in an email that “natural gas and oil power our global economy, which is why most investors and banks are focused on working with our industry to achieve ambitious climate goals together.” She wrote that it’s important to ensure continued access to affordable energy while further reducing emissions, advancing cleaner fuels, investing in new technologies and undertaking other carbon abatement efforts.

The Uniform Prudent Management of Institutional Funds Act, which guides investment decisions for nonprofits, varies slightly from state to state, said Hamilton of the Climate Defense Project. The laws have been in place for about a decade, and the attorneys general have oversight over the charitable institutions in their states.

Students are hoping the complaints will spur their universities to divest. Hamilton said they would also like to see attorneys general help set guidance around the ethical obligations of such investors. They could open investigations into the matter, or issue orders mandating that the universities stop investing in fossil fuels, he said.

“A public charity can’t only be thinking about profit,” Hamilton said. “They have other obligations. We’re trying to make that a concrete legal fact.”

In December, Vanderbilt University’s chancellor, Daniel Diermeier, told the student newspaper the Vanderbilt Hustler that divesting would send a message that the best way to address climate change would be to cut off capital for Western oil companies, and that the university should not take “a party line on any policy issue that doesn’t directly affect the operations of the university.”

Miguel Moravec, a civil and environmental engineering graduate student at Vanderbilt, said that the Dores Divest campaign he co-founded concluded that “escalating to legal action is our only choice.”

For Miriam Wallstrom, a senior from New Mexico who’s an organizer with Fossil Free Stanford, her freshman year began with classes canceled because of smoke from wildfires, a symbol to her of the urgency of combating climate change. But despite petitions and student referendums calling on the university to divest over the years, “there’s a lot of frustrations and disappointment and the feeling that we are not being heard,” she said.

“This is an institution that we all love,” Wallstrom said, “and we feel that the board is failing to act in a way that is upholding those values that we believe in.”