7 10 2005

Continuing our look at global warming news, scientists announced in late September that Arctic sea ice was at the lowest level in recorded history, covering a little over two million square miles, off nearly twenty percent from the long-term average coverage, which is about 2.4 million miles. The date when the melting begins has moved forward about 17 days from when accurate observations began to be taken in 1978.

On land, the snow has melted about 2 and a half days earlier in each of the last several decades, leading to the tree line moving northward and the growth of small shrubs in what was formerly open tundra.

Trees act as solar collectors and help heat the ground, making it warmer. Bare ground absorbs more heat than snow-covered ground, making it warmer. Open ocean absorbs more heat than ice-covered ocean, yes, making it warmer—and the details of the observations I cited reveal that the thaw is not just happening earlier, it’s happening earlier and earlier—the momentum of global warming is picking up speed. Long-term climate records found in the Greenland ice cores disclose that climate change tends to start with small fluctuations that build, cross a threshold, and then move rapidly—over a few decades—to a new equilibrium, sometimes radically different from the climate that prevailed before. To give a concrete example, the last ice age didn’t feature glaciers grinding slowly down from the north. They were built up by twenty or thirty years of really bad weather. That’s why the Russians used to find mammoths frozen to death with flowers in their mouths.

We don’t have enough experience with the weather to really know what will happen when, say, the arctic ocean melts off, but here’s one scenario: the ice cover has prevented the evaporative cycle that creates precipitation on the shores of oceans. When it is gone, there will be increased precipitation in the Canadian and Russian arctic, but the temperatures will stay cold enough that most of it will fall as snow, which will reflect sunlight instead of absorbing it, and it will get deep enough to turn into ice and we’ll be launched into another ice age, made particularly pernicious by the greenhouse effect, so that the planet will be warming in many places as it cools off in others. This highly polarized climactic scheme will cause extreme weather conditions—how about category 8 hurricanes, with winds over 250 miles an hour?

And all for short term gain, from using coal and oil to have a more materially comfortable way of life…..who woulda thunk it?




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