Antarctica's 'Doomsday Glacier' is hemorrhaging ice faster than in the past 5,500 years

Last year there was the report that stated geothermal activity was partially responsible for melt.....

“Our measurements show that where the Earth’s crust is only 17 to 25 kilometres thick, geothermal heat flow of up to 150 milliwatts per square metre can occur beneath Thwaites Glacier. This corresponds to values recorded in areas of the Rhine Graben and the East African Rift Valley,” says AWI geophysicist and first author of the study, Dr Ricarda Dziadek.

Is this still part of the story?
See also: .

Note the part about the central part of Antarctica being open water in the last interglacial period about 120,000 years ago. That would be consistent with the sea level then being about 25 feet higher than it is now.

It looks pretty hard to decipher what amount of this glacial melt process is human-induced, and what part is cyclic.

But, whatever the causes, it sure looks like we should be planning for many feet of sea level rise in our future. The real question is "how fast".


"Science begets knowledge, opinion ignorance.
I am not underestimating the ice melting, and its effects on sea water level, but I have, in fairness, to point out the critical point of the origin of the ice.

The greatest problem, of course, is ice (glaciers) originating on the land in Antarctica. This melting ice goes directly to raising sea level. Ice already floating on the sea makes very little difference, due to Archimedes Principle. In fact, there would be no difference, but for the difference in density of sea and fresh water being about 3%.

However, once the ice actually breaks away and floats, the damage is done. By Archimedes, the level will not increase (except for the paltry 3%).

Cat :)
There is a lot of ice built up above sea level on what we think of as the Antarctic Continent. The base of the ice in the central portion is resting on bed rock that is below sea level, but the ice above that is not floating. Thwaite's Glacier is not floating, either. It is effectively sliding down hill, but some of it is sliding over a lip that tends to make it slide more slowly than if it was just on a sloped plain. Once it gets to the edge of the land, it starts to float and becomes an "ice shelf" with water able to circulate under it and add some warming from below.

Where sea level is on the Antarctic Continent has a lot to do with how much ice is stacked on top of the rock. The land actually has sunk down because of the 10,000 feet of ice sitting on it right now. AFTER that ice melts, the land will slowly rise, again. So, exactly what was and will someday again be above sea level in Antarctica is somewhat hard to understand. That calculation has been done for Greenland. I'll see if I can find that again, later, and post it here if I find it.
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"Science begets knowledge, opinion ignorance.
Fine. I understand what you are saying, but that does not affect Archimedes Principle.

Of course, ice on land will, on reaching the sea, be responsible for increasing sea level. My point is that once it is floating, it has already had that effect. You do not have to wait for it to melt.

Cat :)
Cat, although I understand Archimedes Principle says that floating ice will not increase water level by melting, I am not understanding why you are bringing that up. The glaciers and ice sheets that create them on the Antarctic Continent are not floating. There are some ice shelves floating around the periphery of the continent, which come from glaciers flowing into the sea. The faster they flow into the sea, off of bedrock, the more ice displaces some sea water and raises the sea level, even before it melts. So, unless there is sufficient snow fall in Antarctica to balance the ice lost to glaciers sliding off the land into the sea, the movement of the glaciers into the sea does cause sea level to rise.

A more subtle effect is that the weight of the ice lost from the continent will allow the continent to float higher in the Earth's mantel rocks, with the ocean floors and distant continents sinking a little lower to compensate. So, on land local to the ice melt locations, sea level will then seem to get lower, while in other locations, sea level will seem to rise even more than would be expected from just the water level increase due to water volume increase.

I am, as I type this, sitting on a piece of land where "sea level" appears to be rising twice as fast as the average around the globe, because the land is also still sinking from the effects of the last ice age. This locale was not covered by glaciers, so it was squeezed upwards by the nearby land being pushed downward by the ice sheet. The land that was pushed down has been rising since the ice sheets melted about 15,000-to-20,000 years ago, and my property here has been and still is sinking back to where it would be at equilibrium in the mantel without any ice sheets in adjacent lands.


"Science begets knowledge, opinion ignorance.
Please look what I said:

Of course, ice on land will, on reaching the sea, be responsible for increasing sea level. My point is that once it is floating, it has already had that effect. You do not have to wait for it to melt.
New emphasis mine.

This will happen whatever else may contribute to the sea level. If some other factor causes level to increase or decrease, that is a completely separate issue. We are talking relative, not absolute.

That was the only point that I was making.

Cat :) :) :)
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