Map of life expectancy at birth from Global Education Project.

Wednesday, January 06, 2010

The weather

What better subject for small talk? In case you've been wondering why much of the U.S. has been unusually cold lately, it turns out meteorologists actually know why but for some reason it hasn't been discussed much. You've probably heard of the El NiƱo/Southern Oscillation but you probably didn't know that there's also a phenomenon called the Arctic Oscillation, which refers to the relative air pressure in the polar and northern temperate regions. It turns out that after tending to be in the so-called positive phase lately, with higher pressure in the temperate zone, it has now entered just about the strongest negative phase on record. This causes arctic air to spill into the populous regions of the temperate zone, and there you are.

The cause of the oscillation is unknown, and nobody knows how long this negative phase will last. It might not even last the winter, or it might go on for years. While this has no bearing on the accuracy of the anthropogenic global warming thesis -- such variations are expected to be superimposed on the longer term trend -- it certainly could have profound political implications. You probably also know about the 11 year cycle of solar activity. That also happens to be at an unusually strong and long-lasting minimum right now. Again, nobody knows why, but if the sun decides to veg out for a while as well, we could have a few years of cooler than normal weather exactly where most of the people in the wealthy countries live. No matter how much the scientists protest, I am willing to bet the ranch that if people's direct experience is that it just is not getting warmer but instead it's staying damn cold, they aren't going to believe in some mystic claim about what will happen by 2050 and if they do, they're going to be cheering for it.

Fortunately for me, the arctic cold has yet to hit Boston, and it's not in the forecast either. We've had a pretty much normally cold January here. And BTW, it's unusually warm in Greenland. But people aren't going to pay any attention to that.

Of course, the oscillation could turn positive and the sun could perk up starting tomorrow, and we could start melting like a fudgsicle on a summer sidewalk. It all depends.


C. Corax said...

Seems to me that if the Arctic cold isn't staying over the Arctic, we're screwed anyway, no matter how cold it gets in these parts. 'specially folks who live along coasts and on islands (that is, most of the world's population).

Cervantes said...

Basically yes, this doesn't necessarily reduce the global average temp. It does reduce some positive feedbacks however -- depletion of arctic sea ice and melting permafrost -- so it could in fact slow the overall warming process by a bit. No significance in geological time, but in political time, yes.

kirsten said...

Apparently, the Gulf Stream has taken a detour to Greenland leaving the UK in the cold this year.