Heat anomalies at the South Pole: "Like 45 degrees in spring"

"Many scientists around the end are probably gaping right now," says polar researcher Markus Rex.

He and his colleagues have never seen data on temperature anomalies like the ones that have arrived from parts of East Attarctica in the past few days.

A heat record of -11.5 degrees Celsius was measured at the Franco-Italian research station "Dome Concordia".

And the temperature around the Russian station Vostok rose to -17.7 degrees – also a record.

Actually, Vostok's maximum temperature in March is -53 degrees on average, the previous extreme value was -33.

"That's about fifteen degrees more," says Rex, looking at the current readings.

"Incomprehensible!

When we talk about a new temperature record in Germany, it's usually about 0.1 or 0.2 degrees."

Rex is head of the Department of Atmospheric Research at the Alfred Wegener Institute and has been observing the development of Antarctica for years.

His reaction coincides with that of his colleagues.

"This heat wave in Antarctica is changing what we thought was possible in terms of Antarctic weather," writes French geoscientist Jonathan Wille from Grenoble on Twitter.

Torsten Albrecht, member of the ice research group at the Potsdam Institute for Climate Impact Research (PIK), points to the location of the Dome Concordia at an altitude of over 3000 meters.

The measurements are "roughly as if we had measured 45 degrees of heat in Germany in spring."

The lurching of the jet stream

At its core, says Rex, the extremes observed are about the approach of warm air masses.

A warm, humid air flow from Australia hit the Antarctic continent last week.

Rex explains that the southern hemisphere jet stream, moving clockwise around Antarctica, formed "a tremendous wave" and "veered across the inland ice sheet".

A high-pressure system over East Antarctica blocked the moist air masses, preventing them from draining away quickly.

The meandering behavior of the jet stream is nothing special in itself, says Rex.

"But this is the first time we've seen it in this form.

As of today, we don't understand the trigger very well.

We'll be there for more than two or three days."

One question naturally arises here: Are the temperature measurements an indication that global warming is now also having a greater impact on East Antarctica?

Surprisingly, this has hardly been the case so far.

While West Antarctica is warming even faster than the global average, the eastern, much larger part of the continent is showing remarkable stability.

In contrast to that over the Arctic, the Antarctic jet stream has even tended to become more stable, says Rex.

So far, when looking at the Antarctic sea ice, “the absence of a trend” can be observed.

In 2015, an "unusually large extent" was measured, and then in 2017 a particularly small one.

In February of this year a new minimum value was added,

when the earth observation satellites of the EU program Copernicus detected the lowest extent of sea ice since records began in 1979.

Together with the temperature extremes, the sign of an incipient warming?

Concerns about West Antarctica

"The direct effect of global warming cannot explain the measurements," says Markus Rex about the figures from the Dome Concordia and from Wostok.

"This is clearly a weather anomaly, and not every weather anomaly is necessarily caused by climate change." Long-term measurements would have to be awaited to answer the question.

"It will be interesting to see if this becomes a trend now." Heat waves could affect the stability of the entire ice sheet.

"In Antarctic research, it was long assumed that the Antarctic melts primarily from its coasts when warm water gets under the ice shelf," says Torsten Albrecht from PIK.

Heat waves and unusually heavy rainfall, such as those observed in East Antarctica last week,

Superficial melting is now also becoming “possible further and further inland.

Due to the lack of a supportive effect, ice masses inland could also slide faster and thus further increase sea level rise.”

In West Antarctica, melting is already in full swing.

"We don't know whether we're still in a stable state," says Rex, or whether a so-called tipping point has already been exceeded.

Sea level changes are said to be very sluggish: the rise resulting from a collapse of the West Antarctic ice sheet would take several centuries and is likely to be in the range of several metres.

The first part of the latest IPPC report, published in 2021, carefully gives some figures: Over the next 2000 years, depending on the warming, sea levels will rise by 2 to 3 meters (warming of 1.5 degrees) or even 19 to 22 meters (warming of 5 degrees) to be expected.