Bitter cold East Antarctica has sustained an exceptional temperature anomaly of 50-90 degrees Fahrenheit; this has never happened before. Records fell while scientists marveled at an event that is considered impossible as March is the beginning of winter.
Climate models observed some melting after heavy rainfall fell on the ice sheet, but the melt was insignificant. East Antarctica does not have the massive marine extensions of glaciers such as Thwaites. Instead, the rocky coastline is exposed to the sea.
The same area also broke records from April to September with an average temperature of minus 78 degrees Fahnreheight.
From the Capital Gang, writing in the Washington Post.
Parts of eastern Antarctica have seen temperatures hover 70 degrees (40 Celsius) above normal for three days and counting, Wille said. He likened the event to the June 2021 heat wave in the Pacific Northwest, which scientists concluded would have been “virtually impossible” without human-caused climate change.
What is considered “warm” over the frozen, barren confines of eastern Antarctica is, of course, relative. Instead of temperatures being minus-50 or minus-60 degrees (minus-45 or minus-51 Celsius), they’ve been closer to zero or 10 degrees (minus-18 Celsius or minus-12 Celsius) — but that’s a massive heat wave by Antarctic standards.
Wille said the warm conditions over Antarctica were spurred by an extreme atmospheric river, or a narrow corridor of water vapor in the sky, on its east coast. According to computer models, the atmospheric river made landfall on Tuesday between the Dumont d’Urville and Casey Stations and dropped an intense amount of rainfall, potentially causing a significant melt event in the area.
The moisture from the storm diffused and spread over the interior of the continent. However, a strong blocking high pressure system or “heat dome,” moved in over east Antarctica, preventing the moisture from escaping. The heat dome was exceptionally intense, five standard deviations above normal.
The excessive moisture from the atmospheric river was able to retain large amounts of heat, while the liquid-rich clouds radiated the heat down to the surface — known as downward longwave radiation.
Wille explained warm air is often transported over the Antarctic interior this way but not to this extent or intensity. “[T]his is not something we’ve seen before,” he said. “This moisture is the reason why the temperatures have gotten just so high
At the opposite end of the planet, temperatures are 50 degrees above normal in the Arctic, close to the freezing point.