A prolonged warm spell on Eagle Island, off the northern coast of the Antarctic Peninsula that stretches toward South America has caused one inch of snowpack to melt in just a day – four inches in total between February 6th and February 11th. Approximately 20% of the region’s seasonal snow accumulation melted in this one event.
NASA’s before-and-after satellite images (from February 4th and February 13th) present the effects quite dramatically. You can see blotches of blue and brown in the after photo, which are massive ponds of melted water and exposed land – where there was white ice before. Nichols College glaciologist Mauri Pelto was concerned, saying that he hasn’t seen melt ponds develop that quickly in Antarctica.
Two days after the February 4th photo was taken, Eagle Island reached a temperature of 18.3 degrees Celsius (64.9 degrees Fahrenheit) — to put it into perspective, Los Angeles was around the same temperature that day.
Pelto said:
I haven’t seen melt ponds develop this quickly in Antarctica. You see these kinds of melt events in Alaska and Greenland, but not usually in Antarctica. Such rapid melting is caused by sustained high temperatures significantly above freezing. Such persistent warmth was not typical in Antarctica until the 21st century, but it has become more common in recent years.
With average temperatures rising nearly 3 degrees Celsius (5.4 degrees Fahrenheit) over the past half-century, the agency has dubbed the Antarctic Peninsula one of the fastest-warming regions on Earth. Head of Antarctic sciences at the National Science Foundation, Alexandra Isern, says the warm events are occurring more often in that part of the peninsula.
However, she cautions:
We have to understand that those images were taken about as far north in Antarctica as you can get. So, if any place is going to have those melt ponds, that’s certainly going to be one place. Still, it’s surprising to see such a rapid and dramatic shrinkage of snow and ice. You see those sorts of things in Greenland and in the Arctic more often than you see them in the Antarctic.
A combination of weather conditions caused the unusually high temperatures. As NASA explained in a reporting:
A ridge of high pressure was centered over Cape Horn at the beginning of the month, and it allowed warm temperatures to build. Typically, the peninsula is shielded from warm air masses by the Southern Hemisphere westerlies, a band of strong winds that circle the continent. However, the westerlies were in a weakened state, which allowed the extra-tropical warm air to cross the Southern Ocean and reach the ice sheet. Sea surface temperatures in the area were also higher than average by about 2-3°C.
Dry, warm foehn winds also could have played a part. Foehn winds are strong, gusty winds that cause downslope windstorms on mountains, often bringing warm air with them. In February 2020, westerly winds ran into the Antarctic Peninsula Cordillera. As such winds travel up the mountains, the air typically cools and condenses to form rain or snow clouds. As that water vapor condenses into liquid water or ice, heat is released into the surrounding air. This warm, dry air travels downslope on the other side of the mountains, bringing blasts of heat to parts of the peninsula. The drier air means fewer low-lying clouds and potentially more direct sunlight east of the mountain range.
The combination of stronger winds and higher temperatures will make a foehn-induced melt event stronger, as it did in this case. This one event alone isn’t something to be concerned about; it’s the fact that events such as this are happening more frequently that is worrisome. It is the third major melt event in one summer alone, following warm spells in November 2019 and January 2020. Now scientists are focused on figuring out if this is simply a weather event or if it’s on its way to becoming a climate event.
