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When glaciers calve: Huge underwater tsunamis found at edge of Antarctica, likely affecting ice melt.

Bulletin, By Michael Meredith | July 15, 2024

Antarctica is huge, it affects pretty much every place and every living thing on our planet, and it is changing. This should be a concern for all of us, and yet we know troublingly little about some key aspects of the great white continent.

Despite its position in the far distant south, Antarctica is a vital component in the functioning of the planet. It is central to global ocean circulation, thus exerting a profound influence on the world’s climate (Figure 1 on original). The vast Southern Ocean that surrounds Antarctica absorbs huge quantities of heat and carbon dioxide from the atmosphere and distributes them around the rest of the world, thereby slowing the rate of global warming elsewhere. This “climate favor” has comes at a cost, however—the Southern Ocean is overheating and acidifying, with marked impacts on the marine ecosystem. The extra heat in the ocean is also melting the fringes of the Antarctic Ice Sheet, destabilizing its glaciers, and increasingly pushing up sea levels worldwide. The sea ice around Antarctica—formed in the fall and winter of the Southern Hemisphere, when the ocean surface freezes—has now reached record low extents, affecting the Earth’s energy budget and acting to further accelerate climate change.

All the information we have from Antarctica comes from sparse networks of sensors and equipment deployed directly, augmented with satellite measurements of the ice and ocean surface and computer simulations. While we know more about Antarctica and the Southern Ocean than ever before, it is still one of the least-well measured places on our planet, with some areas still remaining “data deserts.” We need to know more, so that we can better understand the causes of the changes happening here, how they will continue to change in future, and hence what the global impacts are likely to be.

One feature of the Southern Ocean that is often overlooked is how (and how strongly) it is mixed. This is a key process that redistributes heat, carbon, nutrients, plankton, and all other things in the sea, with profound consequences. 

………………………………………glacier calving event had caused a sudden massive burst in the mixing of the ocean, stretching many kilometers from the ice front.

How did it do this? The data revealed that the glacier calving had triggered an underwater tsunami event. In essence, large waves (the height of a two-story house) were generated and moved rapidly away from the glacier, riding the interface between layers in the ocean that were tens of meters down. When these internal tsunami waves finally broke—like surface waves on a beach—they caused massive churn and mixing…………………………………………………………………………

This process—of glacier calving generating internal tsunamis and bursts of ocean mixing—is entirely absent from the computer models that are used to simulate our climate and ecosystem, hampering our ability to reliably project future changes. We need to know more about how this process works, how it will change, and what its consequences will be. ……. https://thebulletin.org/premium/2024-07/when-glaciers-calve-huge-underwater-tsunamis-found-at-edge-of-antarctica-likely-affecting-ice-melt/?utm_source=Newsletter&utm_medium=Email&utm_campaign=ThursdayNewsletter08152024&utm_content=ClimateChange_HugeUnderwaterTsunamis_07152024&utm_source=Newsletter&utm_medium=Email&utm_campaign=ThursdayNewsletter08152024&utm_content=ClimateChange_HugeUnderwaterTsunamis_07152024

August 17, 2024 - Posted by Christina Macpherson | ANTARCTICA, climate change