Archive for April 6th, 2020

Antarctica Denman Glacier Quickly Undermined By Warm Water

April 6, 2020

The virus catastrophe was predictable and predicted, and so is the sea level catastrophe, presently unfolding, albeit in slow motion. The virus is virulently ongoing, and, in an healthy reaction, research in biology is ramping up. But research should be ramping up all over. Indeed, the sea is rising, and that, too, is a great catastrophe. It’s also a nonlinear catastrophe, like the virus: first slow, then exponential, because the speed of the effect is proportional to its extent. The poster child of East Antarctica melting down is the narrow outlet of the giant Aurora basin known as the Totten Glacier. Now it has a rival, the Denman Glacier. Warm water is going below the glacier into a previously unknown 1800 meters deep, 5 kilometers wide through.

Denman Glacier is a glacier 13 to 19 kilometers wide, descending north some 130 kilometers, debouching into the Shackleton Ice Shelf east of David Island, Queen Mary Land, East Antarctica. 

The Denman Canyon is immensely deep, the world’s deepest hole. As warm, 4 degree Centigrade water is the densest type of water, this relatively warm water is slipping below the glacier, melting it from below, and this situation is happening all around Antarctica and Greenland…The canyon under Denman Glacier was found by BedMachine Antarctica project (under the leadership of the University of California, Irvine) to be the deepest canyon worldwide. The bedrock being is 3,500 m below sea level: it’s twice deeper than the Grand Canyon. And soon it will be all water.

Problem: more than 4,000 meters of ice is piled up there, above that bedrock 3,500 meters below sea level. Thus, should Delman melt, much water would be added to the oceans. How much? 1.5 meters. Enough to flood all coastal cities, worldwide.A 2020 study reported Denman Glacier retreated 5.4±0.3 km over a 20 year period from 1996 to 2017–2018. So far, so good. However, the bedrock falls away quickly at that point. Hence the glacier will undergo a rapid, irreversible retreat, due to the presence of a retrograde bed on the western flank of the glacier and the likely presence of warm water in the sub-ice-shelf cavity.

Progression of warm water under East Antarctica Denman Glacier until 2018. The grounding line retreated 5.4 kms over 20 years. Water should now fall down another 700 meters pretty quickly. At some point, icequakes will shatter the whole undermined thing.

I have described the situation with the outlet of the giant Aurora Basin, the long and narrow Totten Glacier, a 300 kilometer long, 30 kilometer wide channel, below which warm water was found to have progressed much more than expected. At this point the ice-full canyon is mostly cut off from the sea thanks to all the glacial ice piled inside and atop the deep ravine. However, as the glacier’s edge continues to retreat farther and farther down the slope, warm ocean water will pour into the canyon, undermining bigger and bigger sections of the glacier, which will break off in spectacular icequakes.

The narrowness of the channel along which it is occurring and how much warm water from the deep ocean can be moved through it will control the evolution of the situation. Other outlet glaciers of East Antarctica are in a similar situation: glaciers at Vincennes Bay, Porpoise Bay, and the George V Coast. It is difficult to know their fate without the collection of more data.

Considering the present greenhouse situation, we should have a Miocene situation in Antarctica: much of it melted, or underwater. Because much of Antarctica is below sea level, crushed by kilometers of ice.

Trump said an infrastructure bill should go through, even if it’s not green… He is right, considering the virus situation… And, in any case, considering the improvement of technology, any technological development now is more green than what was done before. Plus, the fact is, the climate crisis will be solved by more technology… And only by that. Just like the virus. And for the same reasons as the virus.

Patrice Ayme