Many Antarctic glaciers are never snow-free. See how remarkably different this year is.

Warmer-than-average temperatures across the continent’s northernmost tip began creeping in during November, lasting through February. By then, several glaciers were nearly or completely free of snow, according to satellite imagery. Preliminary analysis shows the average temperature of the melt season was about 1.5 degrees Celsius above the average at Esperanza Base, located on the peninsula tip. Several regions along the Antarctic peninsula and along the coast further inland experienced 15 to 20 more days of melting than typically seen in a summer.

On Feb. 19, snow covered only 7 percent of Eagle Island ice cap, located on the eastern coast at the top of the peninsula.

Located a few miles slightly southeast, Vega Island was entirely snowless on its eastern end, leaving knobs of exposed bedrock visible in places. Its western end lost 70 percent of its snow cover.

A few miles to the southwest, at least three glaciers on James Ross Island — the San Jose, Lachman and Triangular glaciers — disappeared.

“If I didn’t tell you those were glaciers, you might not think that,” said Mauri Pelto, a glaciologist at Nichols College, Mass. “I think you’d be confused that there’s glaciers in Antarctica that are really struggling.”

Pelto said he hasn’t seen “a period where we have this many glaciers this bare of snow” in satellite imagery from at least the beginning of this century. “From that standpoint, it’s more widespread than any other example I can see.”

Ice shelves further inland, which rarely see significant melting, also felt the heat. The Getz and Sulzberger ice shelves experienced around 10 melt days, which is double the average at this time of year, according to the National Snow and Ice Data Center.

The center also reported that melt ponds — puddles where snow and ice melt and pool — also formed across the George VI ice shelf and rivaled the record extent seen in the 2019-2020 season.

Ted Scambos, a senior research scientist at the University of Colorado at Boulder, said the number of melt days and presence of melt ponds can often signal an intense, warm melt season in the region. This year also set a record low for Antarctic sea ice, although Scambos said the low sea ice may be influenced by factors related to the ocean in addition to human-caused climate warming.

Most of Antarctica’s melting occurs on the peninsula, where temperatures are generally markedly milder than the rest of the continent. While the peninsula experienced a warm summer this year, preliminary analysis of temperatures further inland at the Amundsen-Scott South Pole Station just posted its coldest September-February period since at least 2000 — a fact that underlines how varied the climate is across the region.

Scambos explained that this season’s warm conditions on the peninsula were caused by stronger-than-usual winds coming from the South Pacific and blowing against mountains on one side of the peninsula. These downsloping winds, called foehn winds, are dry but also very warm. They induce a lot of surface melting, especially on the eastern side of the peninsula.

A similar foehn wind event occurred last year and caused above-average melting across the peninsula, said Scambos. “As a result, there have been renewed changes in the peninsula’s permanent ice, glaciers which rest on land, and the ice shelves,” he said.

The peninsula has shown long-term overall warming trends since the 1950s, said Jorge Carrasco, an Antarctic researcher at the University of Magallanes in Chile. Conditions on the peninsula varied over shorter time scales, though: It entered a warming period from around 1951 to 1998, then began lightly cooling for almost two decades. But during this cooling, researchers say, it didn’t cool “nearly as much as it had warmed before.” The peninsula then entered another warming period in 2016 continuing to the present, with the past two to three summers experiencing above-average melt years. Despite the fluctuations, Carrasco said near-surface air temperatures have still shown an overall warming on average.

“Periods under 20 years with both warming and cooling trends are normal in the Antarctic Peninsula, a region that presents a large interannual variability,” said Sergi González-Herrero, an atmospheric and climate scientist at the WSL Institute for the Snow and Avalanche Research in Switzerland.

González-Herrero said many factors could be influencing the longer observed warming, including natural climate drivers, depletion of ozone near the pole — and human-caused climate change.

“Antarctica’s main response to climate change has been a change in wind patterns,” Scambos said. “The peninsula is one of the fastest warming areas on Earth, and that has a lot to do with the general trend toward faster winds [encircling the pole], a warmer Pacific and north westerly winds arriving over the peninsula.”

Scambos explained that the faster winds are related to general warming around the tropical to temperate parts of the Earth, which leads to stronger winds around Antarctica.

González-Herrero said that stronger circumpolar wind patterns are creating more intense foehn wind events, which are more likely to reach record-breaking air temperatures that can accelerate glacial melt.

In February 2020, Antarctica recorded its hottest temperature on record when Esperanza Base on the tip of the peninsula reached 18.3 degrees Celsius (64.9 degrees F). The Eagle Island ice cap experienced intense melting then too, losing about 20 percent of its seasonal snow accumulation in the region in about a week. González-Herrero and his colleagues have found climate warming amplified the 2020 heat wave as well as one in 2022.

“The Antarctic Peninsula is considered a warming spot, a region that is and will be affected by climate change,” said Carrasco.

As temperatures soar higher, the glaciers and the peninsula will continue to feel the effects.

“Glaciers like this that persistently lose all their snow cover and look like this by the end of the summer, they can’t survive,” said Pelto. “Then it’s just a matter of how fast they’re going to melt.”

Satellite imagery via Sentinel Hub