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Friday, January 6, 2012

Arctic Sea Ice Volume (from Stu Ostro's marvelous end-of-the-year summary)

Something which is likely a factor contributing to the atmospheric extremity in/near the Arctic in recent years is the precipitous drop in the amount of sea ice there. The black line on this graph plots the volume, which takes into account both the area and thickness of the ice, at the time of the annual minimum each September.

The colored lines represent different mathematical slopes, and what each would do in the future if it were to follow the respective rates of decrease. Although representing different methods and phenomena compared to computer model forecasts of hurricane tracks, this range of projected potential outcomes could be thought of as analogous to the "spaghetti model" plots that have become commonly used.

Hopefully over the coming years and decades the rate of decline showed by the black line will slow down and follow a path toward zero (no ice left in late summer) more like the purple line than the green one. But the recent and current rate is troubling, given the important role that the Arctic and its ice play in the Earth's climate system, and given that this is happening faster than the climate models predicted.

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