When we initially covered the divestment movement, we chided campus campaigners for making saber-rattling claims that removing a few million dollars here and there (or even everywhere) from university endowments would shake up the energy markets, which simply don’t function that way. Fortunately, divestment activists have largely abandoned that rhetoric. More and more, they emphasize their tactic’s true strength as a source of diversified political pressure—and one which calls on investors to actively finance sustainable sources of energy instead of passively profit from the crisping of the planet.

As I write, the campus divestment movement is still basking in the afterglow of Stanford University’s decision to divest itself of its direct holdings in coal. Stanford is now the eleventh higher-education institution to announce that it will divest in whole or part, and it’s by far the largest, with an $18.7 billion endowment.

It’s not just the suits at Stanford lending prestige to the movement. In January, seventeen foundations with a collective $1.8 billion in assets launched the DivestInvest initiative, announcing their intention to divest from fossil fuels and “switch to clean energy investments.”

“At a minimum, our grants should not be undercut by our investments,” Ellen Dorsey, executive director of the Wallace Global Fund, told the New York Times. She continued, “If you owned fossil fuels in your investment portfolio, it became increasingly clear to foundations that they own climate change, and they’re potentially profiting from those investments,” at the same time as they make grants to fight the issue.

Three Clean Yield clients have taken the Divest/Invest pledge: Singing Field Foundation, the Lydia B. Stokes Foundation, and the Henry and Frances Block Foundation. Individuals can also take the pledge at DivestInvest.org/individual.

Within the sustainable investing movement, there is an ongoing debate about the merits of divesting versus the value gained by “staying at the table” by filing shareholder proposals. Engagement enthusiasts tend to emphasize the lack of economic impact that individual divestments have upon the company whose stock has been sold. There is no denying that divestment’s impact is currently more cultural and political than economic, but in our view, those who disparage divestment overstate the value of engagement with oil companies and gloss over the moral implications of profiting from a disaster-inducing industry.

Based on extensive first-hand experience, we are bearish on the prospects that continued shareholder advocacy at fossil fuel companies will result in those companies transforming themselves in the only way that matter—that is, repositioning their mission from that of fossil fuel pushers to clean-energy providers. The first climate change proposal was filed in 1991. Twenty-three years later, fossil fuel companies still exercise a chokehold on national energy policy and remain stubbornly incapable of acknowledging that around 80% of their known reserves should stay in the ground. Between 2000 and 2011, global greenhouse gas emissions trended upward at an average increase of nearly 3% per year.

Clean Yield and its clients may continue on occasion to co-file a shareholder proposal at fossil fuel companies (using an inherited or “legacy” stock position), but we’re under no illusion that they will result in breakthrough behavioral changes. Faced with shareholder proposals and the prospect of a price on carbon, some in the industry have made incremental improvements in the carbon efficiency of their operations or product. Fossil fuel companies’ disclosures have also improved. But these will not get us where we need to go: back to 350 parts per million of atmospheric carbon.

It is time for the world’s largest investors—public and corporate pension funds, insurance companies and the like—to join Stanford and these pioneering endowments in facing the obvious: 23 more years of owning significant stock positions in the world’s fossil fuel companies is going to leave them holding the bag when the carbon bubble finally bursts, with or without their participation in shareholder proposals.

The institutional investors that are unwilling to divest but continue to profess concern about the viability of carbon-heavy energy projects should put their money where their mouths are—by reducing their portfolios’ exposure to the heaviest carbon emitters in a very public way, explanations attached. Like divestment, reducing exposure would prudently reduce portfolio risk while sending a clear message that it’s past time to shift capital to where it belongs: clean and renewable energy sources.