A glacier located in Antarctica, the Hektoria glacierunderwent the fastest collection ever recorded in modern history: retreated 25km between 2022 and 2023of which 8 km in just two months, in which he lost as much as half of its mass. To discover this enormous loss, thanks to the analysis of satellite imageswere the researchers of Cooperative Institute for Research in Environmental Science (CIRES) of the University of Colorado Boulder. The study, published in the journal Nature Geoscienceillustrates how this unprecedented withdrawal occurred and what its causes were. That of the Hektoria glacier is a special case, because the main factor that contributed to the ice melting was not global warming, but the conformation of the territory. Studying this event is fundamental because in the future glaciers with similar characteristics could undergo the same process and contribute significantly to sea level rise.
The sudden retreat of the Hektoria glacier in Antarctica
The Hektoria glacier it extends in the Antarctic Peninsula, in Western Antarctica, over an area of 295 km2comparable to that of a large city. It’s a tidal glacierthat is, it rests on the rocky substratum of the continent, but then continues into the sea like a tongue of floating ice. Over the course of 15 months between 2022 and 2023 it retreated by 25 kmof which 8 km only between November and December 2022. This is about a melting rate ten times higher than that observed so far in a glacier, not justifiable only by the increase in temperatures, which in December 2022 were not particularly high. Such rapid ice loss is believed to have occurred in the glaciers of Norway at the end of the Last Ice Age, between 15,000 and 19,000 years agodue to rising temperatures. This impressive phenomenon was revealed to researchers by the satellite images and aerial. “When we flew over the area, I couldn’t believe the enormity of the collapse,” says study author Naomi Ochwat. “I had seen the satellite data, but seeing firsthand the absence of ice where it previously stretched for kilometers was shocking.”
Why the glacier retreated so quickly: the study
To explain the anomaly of the Hektoria glacier, thanks to satellite images and seismic data, researchers reconstructed the dynamics of ice loss. Initially the presence of sea ice close to the terminal part of the floating glacial tongue, by blocking it, it contributed to avoiding any detachments. At the beginning of 2022, however, an intense wave caused the sea ice to break up. At this point some people began to detach themselves from the Hektoria language iceberg. A quick one followed thinning of the portion of the glacial tongue that rests on the flat rock platform with which the Antarctic continent immerses itself in the ocean, located below sea level. As the ice thinned, sea water infiltrated between the rock and the glacial tongue, lifting it. In this way it favored the fracturing and rapid detachment of other blocks and thefurther retreat of the glacierwho continued to retreat until he encountered one rocky step higher than the underlying platform. By breaking off, the icebergs generated earthquakes that were recorded and helped researchers reconstruct the dynamics of the phenomenon.
The Hektoria glacier is not the only one in Antarctica with this conformation: other glaciers on the continent they also rest on rocky platforms immersed in the ocean. Some are much larger in size and their sudden fusion could contribute significantly tosea level rise. Field surveys and observations of satellite images are therefore needed to identify and study the areas at risk.
