It’s been snowing continuously here for about 2 days. The heaviest snows I’ve experienced in my life (for any significant amount of time) were an inch an hour, but this has been half that — amounting to a foot a day.
If it were to keep snowing like this for a week, it would be a major emergency; if for a month, the area would become uninhabitable.
As usual, people who disbelieve in global warming point at the record snow coverage extents this year and say they disprove it. As usual, people who are global warming supporters claim that global warming is causing the snow.
GCMs tend to have forecast lower snow cover with rising global temperature, indicating a positive albedo feedback. That much seems clearly wrong. On the other hand, it’s not totally counterintuitive that rising energy input in the tropics could cause more evaporation, feeding more water into an atmospheric conveyor leading to more snow in the cold places. This could actually form a negative feedback in the climate system, putting an upper limit on global temperatures. There has to be some kind of such a limit, since something appears to stop the positive feedback loop (between temperature and CO2) that drives the exponential takeoff out of ice ages into interglacials.
Anyway, snow. Whatever the reason, we’re about 3 months of what it’s doing right this minute from an ice age. I don’t have a clue how likely this is to happen how soon, but looking at the last million years of climate, ice age is the normal condition of Earth and interglacials are few and far between.
We can only hope we’ve had the sense to develop real nanotech before we’re back in one.