I’m pretty sure that, all its defensive sputtering aside, Harvard will eventually divest its holdings in fossil fuel companies. Four reasons come to mind:

First, the logic of the divestment campaign has so far gone unassailed. No researcher, and not even any oil executive, has disputed the core idea students have been putting forward for two years now: The fossil fuel industry has many times more carbon in its reserves than researchers calculate the atmosphere can handle. If Exxon et al. follow through on the promises made to shareholders and governments—the promises to dig up their reserves and sell them—then this industry will make massive climate change inevitable: There’s no mystery about it anymore, no drama. If they carry out their business plans, the planet tanks.

Once you know those numbers, these are no longer normal companies. They are rogues, breaking not the laws of the nation, but the laws of physics. And there is no gentle way to rein in rogues: So far this year, both Exxon and Shell have made formal announcements that they plan to burn everything in their reserves and keep on hunting for more hydrocarbons. Having the proverbial “seat at the table” to discuss change is, in these cases, useless, since there’s not a fixable flaw in the business plan of these firms. The business plan is the flaw.

Students know all this—they understand the grave importance of this battle. They know that heroes of the past, like Desmond Tutu, have joined their voices to the call. But they know, much more, that their future demands action. If we can’t quickly break the power of the fossil fuel industry, then we’ll never get the logical steps, like a tax on carbon, that would give us some chance of breaking out of our global logjam. That’s why students have proceeded with such vigor: polite and well-informed, but firm and persistent. They are organizing with all the passion of their predecessors in the eras of civil rights or Indochinese war—and with the all the networking might that comes in the age of Facebook and Twitter.

And—probably most crucially—students have a great ally in their fight. Not just the faculty, who have begun to chime in loudly; not just alumni, most of whom have graduated in the years since we started understanding climate change. But most of all Mother Nature.

Every week she adds another sad but powerful layer to the case against carbon. This month, it was not just the record heat spawning fires in San Diego or record rains producing monster floods in Bosnia; it was also the gut-wrenching news from the South Pole that the West Antarctic ice sheet is now in motion, melting with sinister speed as warm water begins to float it from beneath. Harvard owns a piece of those fires and floods; all of us who’ve made a donation have a share in that melt. That’s literally where the money that we’ve given over the years is now invested.

College administrators have an ever-bright hope that their student adversaries will graduate and issues will disappear. But in this case, the flood of horrifying data will only grow, a mounting toll that will eventually grind down even the mighty Harvard Corporation. At some point—as Stanford has already concluded—they’ll figure out that they don’t want to be on the wrong side of the greatest crisis our species has ever wandered into.

But damn, let’s hope it doesn’t take as long as it did for Harvard to begin, grudgingly, to divest from apartheid South Africa. Because global warming is a timed test, and every semester that goes by digs our hole deeper. Students will win this fight, but the rest of us need to help them win quickly.

So write a letter to Massachusetts Hall—a letter, not a check. Tell them you love Harvard, love it enough that you want to see it live up to the standard set by its physicists and philosophers. Divest because of the typhoon in the Philippines and the rapidly acidifying ocean. Divest because we’re headed for the sixth great extinction. Divest because Harvard disgraces herself when she arrests peaceful protesters. Divest because if you’re alive when the Antarctic begins to disintegrate and you don’t act, then your soul will start to wither. Divest because this place, so soaked in the past, is really about the future—a future that won’t exist unless we get very fast to work.

Bill E. McKibben ’82, a former Crimson president, is co-founder of 350.org.