Apparently this has come from the efforts of -- you guessed it -- Bill McKibben, bad math and all.
Actually I think this not a bad idea, but I also don't think it will work.
In short: it's easy to protest against things that don't cost you anything.
When I was in college, there was an effort among college organizations for their universities to divest from companies who did business in South Africa. I wasn't part of these efforts, mind you -- I was too busy with a double major in physics and mathematics. And I've never been able to be part of that kind of crowd anyway.
But the protest worked, and it helped end apartheid there, in its way.
Apartheid -- the segregation and disestablishment of blacks in South Africa (as if it needs explaining, but these days it might) was a hideous moral crime. It followed the struggle of blacks in the U.S. in the 1960s, and so was easy for my generation to identify with -- we grew up (barely) cognizant of that struggle, with the moral ground already well plowed.
And violations of basic humans rights are easy to understand anyway.
Not so much with climate change. Every college student out there today is highly dependent on a vast energy infrastructure that runs almost entirely on fossil fuels. (At last count, only 9% of US energy came from renewable sources, over the last 12 months.)
Turn all that off? No way -- of course. (How would McKibben get to his next protest?)
Use all renewables? Watch the students complain when their tuition goes up to cover the increased cost of renewable energy.
It all comes down to what Roger Pielke Jr calls the Iron Law of Climate Policy:
When policies on emissions reductions collide with policies focused on economic growth, economic growth will win out every time.That's it. That's the bottom line, every time, all the time.
Until noncarbon energy is cheaper than, or at least equal to, the price of fossil fuels, there will be no cutbacks. Period.
So, in my opinion, what these students ought to be protesting for is (at the least) a carbon tax, to incentivize R&D into non-C energy. Better yet (IMO) is a serious federal research program -- $10-20 billion/yr -- into technologies like nuclear fusion and air capture and carbon sequestration. Continued tax breaks for solar and wind. Credits for home-based solar panels. Drive up the demand for solar panels, and (unexpectedly) you will help drive down the price.
We can't stop using energy, and that's the difference from South Africa