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If CO2 is overheating Greenland, why is
the ice still over 10,000 feet thick?
This is a really good question, because it addresses the concept of thickness,
which is extremely important to polar scientists.
It's very easy to see that ice sheets and ice shelves and sea ice are changing
in a sort of spatial sense, but what's even more important
is that they are also thinning. It's very important for sea ice,
but it's also important for the ice sheets.
We know from satellite data and mosaics of that satellite data
that our sea ice extent is decreasing in this sense, the sort of planar sense,
and our ice sheets calve off so we lose mass in that extent as well.
But more importantly, we're getting thinning.
Both in the sea ice and in the ice sheets and you can imagine
that just a little bit of thinning spread over the scale of a continent amounts to a lot of water.
So it's a great question, but I think we just have to fine tune the questioner's expectations.
If I were to walk outside on a really cold day, it would take a little bit of time
for my core body temperature to drop even though I am feeling chilly on the outside.
That's what's happening in Greenland as well. The Greenland ice sheet is really thick.
It's going to take a lot of time to melt all of that ice.
So the Greenland ice sheet is thinning, and it's thinning variably but mostly along the coastlines.
It's thinning beyond our expectations and all of that thinning is taking place upstream of where the ice sheet is grounded.
Therefore that is going right into the ocean and contributing to mean sea level rise.
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