Monday, February 25, 2008
Warming/Cooling
I just read an article in a conservative web site that notes that snow cover for the northern north American continent is higher than any times since the sixties. Naturally, the article implies that because of that, global warming must be wrong. Here's my take on that. Honestly, I don't know. I've seen a lot that supports human-powered global warming, but there's also a lot of evidence that the climate is highly variable historically, and even more so pre-historically. I've also read some articles that climate warming can (and will) suddenly collapse into a major freeze.
Now, having no scientific evidence for any of the above, I can see how a global warming period could increase snowfall in the northern climes. First, if the average temperature of winter is 25 degrees (rough non-scientific Fahrenheit degrees for my 45 degree latitude) a five degree climate warming is still going to give an average temperature under freezing. That means the snow won't melt when it hits the ground. On the other hand, like now, it means the Great Lakes probably won't completely freeze over. This gives you more water to evaporate, which means more water in the air, which since it's below freezing, means more snow. And the more snow, the more the sunlight is reflected away, thus making it colder and keeping more snow. I don't know for sure, but I'm thinking it's not impossible for the dark lake waters to absorb a bit more heat than the glaringly white snow and ice, which would tend to raise the temperature of the water a bit more, leading to more evaporation, etc.
This mechanism by the way, is what in some stories I've read, triggers the next ice age. The wide-spread highly reflective snow covers more ground, causing more heat to be reflected back, lowering average temperatures, causing more snow to cover more ground, etc. Eventually there's enough snow covered ground for the reflective infrared heat to be bounced back so that summer never quite makes it. Boom, an ice age in a season. Who knows?
Labels: tech
