AAAS: “Antarctic glacier shows fastest retreat in modern history.” The Hektoria Glacier is a small river of ice that slips into the sea near the tip of the Antarctic Peninsula, which aligns with Tierra del Fuego of South America. “In 2022, something ‘shocking’ happened—as over 16 months, it retreated by 25 kilometers—losing a whopping 8 kilometers in just two of those months—the fastest glacial retreat in the modern record. “Now, after a forensic analysis of the event reported today in Nature Geoscience, researchers say they have identified the worrisome mechanisms behind it: a combination of glacial earthquakes and a swath of thinned ice popping afloat and breaking apart in a geological instant.”
The researchers first ‘first had to establish its original grounding line: the point at which a glacier is no longer attached to bedrock and becomes a floating ice tongue.’ They were able to use “satellite data on the height of the ice surface, as well as images of surface depressions—a marker of thin, floating ice with cracks underneath—they determined that half of the 25 kilometers of lost ice had been grounded.” Their theory explained how both grounded and floating ice retreated beginning 20 yrs earlier, when Hektoria fed into the Larsen-B ice shelf, a massive, Rhode Island–size, 200-meter-thick slab of ice. “Larsen-B broke up spectacularly in 2002, undamming Hektoria, which initially retreated. In the years that followed though, sea ice formed and thickened, slowing the glacier and keeping it in place for more than a decade.” Simultaneously, Hektoria’s ice was stretching and thinning out across the flat bedrock underlying it, forming what’s known as an “ice plain.”
Imagine here a thin layer of ice on a puddle, breaking apart when you step on it. When storms sent large waves crashing into its margin in 2022, they cleared out the protective sea ice and Hektoria’s first 12 kilometers of floating ice broke up into icebergs, in a process called “buoyancy-driven calving.” More damage followed when the force of the breakup flipped some of the icebergs “toes out,” momentarily + loudly reversing their momentum into the glacier behind them. These collisions generated glacial earthquakes that were detected by a network of seismographs. And with the shock waves reverberating through the mass of ice, the remaining part of the ice plain broke free.
“The one-two punch of flotation and quakes was enough to account for Hektoria’s 8 kilometers of retreat over 2 months, a pace that’s an order of magnitude [base 10] faster than any in the modern record.” The researchers wonder “whether the same kind of catastrophic calving could occur at the much larger Thwaites Glacier, which is sometimes called the Doomsday Glacier because its retreat could unleash more than 3 meters of global sea level rise.” This could takes centuries of course, but this study is “telling us that those worst-case scenarios are maybe not as implausible as some people might have thought.” Sort of thing that keeps climate scientists up at nite. Hate to say it, but this is what the fossil fuel industries are accomplishing, plain as day.
