In a few months, a small British financial think tank will mark the tenth anniversary of the publication of a landmark research report that helped launch the global fossil-fuel-divestment movement. As that celebration takes place, another seminal report—this one obtained under the Freedom of Information Act from the world’s largest investment house—closes the loop on one of the key arguments of that decade-long fight. It definitively shows that the firms that joined that divestment effort have profited not only morally but also financially.

The original report, from the London-based Carbon Tracker Initiative, found something stark: the world’s fossil-fuel companies had five times more carbon in their reserves than scientists thought we could burn and stay within any sane temperature target. The numbers meant that, if those companies carried out their business plans, the planet would overheat.

At the time, I discussed the report with Naomi Klein, who, like me, had been a college student when divestment campaigns helped undercut corporate support for apartheid, and to us this seemed a similar fight; indeed, efforts were already under way at a few scattered places like Swarthmore College, in Pennsylvania. In July, 2012, I published an article in Rolling Stone calling for a broader, large-scale campaign, and, over the next few years, helped organize roadshows here and abroad.

Today, portfolios and endowments have committed to divest nearly fifteen trillion dollars; the most recent converts, the University of Michigan and Amherst College, made the pledge in the last week. No one really pushed back against the core idea behind the campaign—the numbers were clear—but two reasonable questions were asked. One was, would divestment achieve tangible results? The idea was that, at the least, it would tarnish the fossil-fuel industry, and would, eventually, help constrain its ability to raise investment money.

That’s been borne out over time: as the stock picker Jim Cramer put it on CNBC a year ago, “I’m done with fossil fuels. . . . They’re just done.” He continued, “You’re seeing divestiture by a lot of different funds. It’s going to be a parade. It’s going to be a parade that says, ‘Look, these are tobacco, and we’re not going to own them.’ ” The second question was: Would investors lose money? Early proponents such as the investor Tom Steyer argued that, because fossil fuel threatened the planet, it would come under increased regulatory pressure, even as a new generation of engineers would be devising ways to provide cleaner and cheaper energy using wind and sun and batteries.

The fossil-fuel industry fought back—the Independent Petroleum Association of America, for instance, set up a Web site crowded with research papers from a few academics arguing that divestment would be a costly financial mistake. One report claimed that “the loss from divestment is due to the simple fact that a divested portfolio is suboptimally diversified, as it excludes one of the most important sectors of the economy.”

As the decade wore on, and more investors took the divestment plunge, that argument faltered: the philanthropic Rockefeller Brothers Fund said that divestment had not adversely affected their returns, and the investment-fund guru Jeremy Grantham published data showing that excluding any single sector of the economy had no real effect on long-term financial returns. But the Rockefeller Brothers and Grantham were active participants in the fight against global warming, so perhaps, the fossil-fuel industry suggested, motivated reasoning was influencing their conclusions.

The latest findings are making that charge difficult to sustain.

The Powerful New Financial Argument for Fossil-Fuel Divestment | The New Yorker