vincentML
Posts: 9980
Joined: 10/31/2009 Status: offline
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quote:
ORIGINAL: Moonhead Well the arctic icecap isn't landlocked, so it's already displacing its mass in the sea at the moment. There could well be problems when the greenland or antarctic ice melts, though. Moon, let me report something I do not understand. Perhaps you or some others might clarify it for me. It is a controversy. From circa 800 to 1300 c.e. the Norsemen established colonies based on agriculture, animal husbandry and fishing in Iceland, both southern coasts of Greenland, and Newfoundland. The summer climate was balmy enough for 500 years to allow safe passage between Norway and the western colonies. The Medieval Warming. In summer both southern coasts of Greenland were free of Ice. What caused the Warming? The climate changed rather suddenly around 1315 with the beginning of the Little Ice Age that lasted until about 1850. What caused the change? That's bad enough. But there is more to the controversy. Climate is effected by air temperatures and sea temperatures. Everyone agrees that the UK is kept relatively warm for its latitude because of the tropical water brought north and then east past Iceland by the Gulfstream. Many scientists argue that the Gulfstream is a windblown phenomenon. Others argue it is part of a North Atlantic Convection Current aka the Thermohaline Circulation. Sheesh! As I understand it, the warm surface water of the GS mixes with cold seawater in the northern latitudes. The cold mixture has greater density than the warm surface water and so sinks to 9000 feet (or wherever) and flows southward at great depth. The circulation involves a northward flow of warm surface water replaced by a southward flow of deep, cold current. A convection current. Here is the controversy. Some have argued (and warmers have denied) that as the ice melts from the Greenland shelf it dilutes the sea water thus reducing its density and slowing the sinking of cold water. The southbound, deep ocean convection slows. It in turn slows the northbound GS surface convection. Northbound warmth is reduced and the lands bordering the North Atlantic once again become cold. The ice pack grows again. I have read counterpoint that computer models do not replicate this system. It will not happen goes the argument. Well, something happened to cause a rather abrupt change from the Medieval Warming Period to the Little Ice Age. All of this is pre-industrial history. Perhaps climate history trumps computer models. If so, it is unlikely all of the Greenland ice will slide into the sea. I wonder if someone can offer an explanation and/or counterpoint. I would sure like to understand it better. Vincent
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vML Our lives begin to end the day we become silent about things that matter. ~ MLK Jr.
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