There's a positive feedback loop I'm watching which could prompt some very quick changes in the very near future: as you mentioned, the melting ice sheets are reducing the albedo of the area. The catch though is that the ice has had several centuries to build up to its current level, and so the ice is quite thick in some places, especially near the pole. What this means is that much of the energy being absorbed by the arctic, especially near the pole itself, is currently going into reducing the thickness of the ice sheet, in addition to shrinking it in terms of area.
Each year a little more melts, and what's left is both a little smaller and a little thinner; and these effects both mean that next year, the winter build up would, even ignoring that it's a little less each year as well, replace less and less of the ice; with the effect being greater than what is obvious merely from looking at the decline in ice area.
At some point, and I think there's a good case for saying we're either there already or getting quite close, there's not enough thick ice left for the sea ice to be stable, and what happens next is a rapid change, since what's left can come undone quite quickly in the summer, and then the ice free Arctic Ocean sucks up heat and thus there's a dramatic reduction in how much ice coverage forms in the next winter.
Add to this that melting all that ice absorbs a lot of heat (water has a very high specific heat of melting, to use the technical term), and once the Arctic Ocean is ice free all that heat which currently goes into melting the ice will go into warming the ocean; and this means that once that happens the pace the ocean warms is going to shoot up like a rocket.
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branchandroot
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Date: 2022-05-15 04:13 am (UTC)Each year a little more melts, and what's left is both a little smaller and a little thinner; and these effects both mean that next year, the winter build up would, even ignoring that it's a little less each year as well, replace less and less of the ice; with the effect being greater than what is obvious merely from looking at the decline in ice area.
At some point, and I think there's a good case for saying we're either there already or getting quite close, there's not enough thick ice left for the sea ice to be stable, and what happens next is a rapid change, since what's left can come undone quite quickly in the summer, and then the ice free Arctic Ocean sucks up heat and thus there's a dramatic reduction in how much ice coverage forms in the next winter.
Add to this that melting all that ice absorbs a lot of heat (water has a very high specific heat of melting, to use the technical term), and once the Arctic Ocean is ice free all that heat which currently goes into melting the ice will go into warming the ocean; and this means that once that happens the pace the ocean warms is going to shoot up like a rocket.