I've republished this post because of the good comments someone has made.
http://www.sciencedaily.com/releases/2011/02/110204092149.htm
ScienceDaily (Feb. 7, 2011) — The substantial decline of Arctic sea ice in recent years has triggered some fears that the ice cover might be approaching a "tipping point" beyond which the loss of the remaining sea ice would become unstoppable. However, new research carried out at the Max Planck Institute for Meteorology in Hamburg/Germany now indicates that such tipping point is unlikely to exist for the loss of Arctic summer sea ice. The sea-ice cover reacts instead relatively directly to the climatic conditions at any given time. Hence, the ongoing loss of Arctic sea ice could be slowed down and eventually stopped if global warming were to be slowed down and eventually stopped.
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There are some good comments for this post. I have tried to change my blog so that comments appear in-line, but I think I would have to go thru a conversion process which I haven't had time to do.
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5 comments:
we've got a snowball's chance in hell that the warming could ever be stopped that abruptly...
rjs, I too am very pessimistic that we will take action in time. But I hope the recent horrible weather events, caused by shifts in polar wind patterns allowing the arctic cold to come come into the states, will bring needed change. I would think it is hurting business profits, so the power elite might take action.
patricia, we have been under the influence of a negative arctic oscillation, and that is changing...the best way to understand what has happened this winter is to think about what happens when you open your refrigerator; the cold air spills out on the floor, and warm air enters the top; that is analagous to what has happened over north america this winter, and, exacerbated by the el nino, last winter as well...the map ive linked to is that of the temperature anomalies for north america covering the period from mid december to mid january; you can note from that that large parts of baffin island, between greenland and canada proper, had a temperature exceeding 21C, or about 38F above normal, averaged over the entire month, an amazing amount to be sustained over an entire month…additional large parts of the canadian tundra were well over 10C above normal...there's two problems i see here that this condition will exacerbate; first, we know that large amounts of frozen methane, a potent greenhouse gas, is frozen in the permafrost and is released when the permafrost thaws; by not freezing deeper this winter, it sets us up for a summer when this methane feedback accelerates...similarly, the east siberian ice shelf, which i posted about last spring, has methane-hydrates frozen at high pressures on the seabed floor, and as the water warms, it thaws & methane bubbles into the atmosphere, and east siberia has also been moderately warmer this winter...although overall not as important a greenhouse gas as CO2 because it's quantities are a magnitude less, it's increased presence in the atmosphere is accelerating more rapidly than CO2 is: pre-industrial CH4 was about .7 ppb and its now at 1.8 ppb...the other problem relates to the ice loss from greenland; the melt has been accelerating exponentially and is now twice what it was a recently as 2002; if one could take all the ice that had melted off greenland this past year and put it on top of new jersey, it would cover new jersey with 257 feet of snow...
sorry, i forgot a link: the east siberian ice shelf
Thanks. I didn't realize the magnitude of the increase in temperature in the north.
As you say, methane is far less abundant then CO2; it also doesn't remain in the atmosphere nearly as long, but it has 20 times as much greenhouse effect than the same amount of CO2. Even though it is not nearly as long-lived as CO2, it is still a problem because of the positive feedback effects you refer to.
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