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Ward Hunt Ice Shelf Breaks In Two
heidi writes "CNN has this story on the breakup of the largest ice cap. A permanent feature for the previous 3,000 years, it has broken into two pieces. "The Ward Hunt Ice Shelf, on the north coast of Ellesmere Island in Canada's Nunavut territory, broke into two main parts, themselves cut through with fissures. A freshwater lake drained into the sea, the researchers reported.""
No, but I do have a PhD in modelling glacial systems during the last Ice Age, so I'll give it a go (appolgies for only using examples from the gulf stream in the N.E.Atlantic, that's the region that I know).
There is a potential risk to the warm surface currents from the loss of floating ice, though it isn't to do with a one-off influx of fresh water. This will rapidly disperse over the ocean and make no perceptable difference.
However, the 'pump' driving the global conveyer is the constant differential melting and freezing at the base of the sea ice. Sea ice is essentially floating fresh water. If you freeze part of sea water into fresh water you are left with dense, cold, salty water. This sinks to the bottom, and then flows south from the arctic. Warm, surface water then flows north to replace it, forming the Gulf Stream (and other similar currents around the world).
Over the last few decades the extent of sea ice in the Arctic has shrunk noticably. There must be a point at which this will have an effect on these currents[1].
It is not clear what the level of sea-ice required to maintain the currents is, nor on quite how the currents will respond (gradually decreasing or simply shutting down). However there is evidence from the sedimentary record of the last interglacial that the gulf stream in the North East Antlantic, at least, switched on and off a number of times, and that the switch from 'on' to 'off' was very rapid.
There is thus the possibility that current climate trends will result in a situation in which the flow of warm water to the N.E.Atlantic may cease (or dramatically reduce) over a timespan of years or decades, producing dramatic climate changes in north Western Europe (especially Iceland and North Norway, but Britain, Ireland and France are also major beneficaries of the Gulf Stream). The lack of transfer of heat from the warmer regions may also result in higher sea-surface temperatures in those regions, which in turn could provide more energy for severe bad weather and hurricanes. There are futher possible effects from the lack of the cold water current. These are important in carrying oxygen around the oceans, and when they upwell against continental shelves they bring nutrients from the deep ocean to the surface, producing rich fishing grounds.
[1] It is also, incidentally, having a major effect on polar bears, which rely on sea ice in their hunting.
You, sir, are so wrong it hurts my eyes to read!
Place a big chunk of ice in a container and fill it with water. Then sit back and see how the melting of ice does not rise the water level. Then get back to your physics books and figure out why it doesn't.
The problem with global warming is not with floating ice. It's with Antarctica where ice is sitting on the continent. Melting of that ice will rise the sea levels.