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The Arctic Ocean off the Siberian coast (archive image)
Photo: Roger Tidman / Getty Images
For millennia, the shallow water areas of the Russian shelf were the nursery of the Arctic ice.
Over the course of many months, the ice masses formed anew here every year, which later - getting thicker and thicker - drifted over the pole to finally melt again in the Fram Strait between Greenland and Spitsbergen.
That was the mechanism of the Arctic for a long time.
But the ice machine has been stuttering for a long time.
Now researchers are reporting a dramatic negative record: "In the Siberian Arctic, there has never been so little ice on the time scales that are relevant to humans," says Gunnar Spreen, head of the Remote Sensing Section of the Polar Regions at the University's Institute of Environmental Physics Bremen.
Spreen studies the extent of the sea ice with satellites.
And when he currently looks at the pictures of the Laptev and East Siberian Seas, he sees - next to nothing.
No ice, anyway.
"Normally the Laptev Sea should be completely covered by this time of the year," says Spreen.
But at best just offshore you can see some frozen areas.
Icon: enlarge Photo: University of Bremen
According to the researcher, a negative record was already set in spring for ice expansion.
Overall, this summer the Arctic landed at the second lowest ice extent since satellite measurements began a good 40 years ago.
At the end of summer, 3.8 million square kilometers of ocean surface were still covered by ice in the far north.
Even directly at the North Pole, the "Polarstern" crew reported that the ice was "soft and full of holes" and that the situation was "historic".
The scientists look back to the time before the satellite measurements with computer models, which are fraught with some uncertainties.
But even if you include that, says Spreen, the current mini ice extent is extraordinary.
But how does it come about that open water sloshes where clods should have long since grown again?
Extreme air temperatures
When the ice with its white surface melts, less incoming sunlight is reflected into space in summer.
Instead, the darker sea water stores some of the energy like, say, a giant heating pad.
This then ensures that less ice forms - and temperatures continue to rise as a result.
The long-term average warming of the Arctic is already significantly stronger than on the rest of the planet.
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Light and dark: breaking sea ice in the Canadian Arctic
Photo: David Goldman / dpa
But this effect could at best partially explain the current negative record, says Spreen.
Because the fact that there is no ice in the Laptev Sea in summer is not unusual.
The solar radiation has therefore also heated the water in other years.
However, this spring, large, open bodies of water could already be seen in April - much earlier than in other years.
Strong winds pushed the ice away from the land into the central Arctic, and the open waters of the coastal seas had longer time to absorb heat.
The storms may also have caused greater mixing of the water column in the ocean - and thus more effective heat transport into deeper layers.
The other part of the explanation for the current negative record can be found in the atmosphere: "The air temperatures in this area are at least ten degrees above the current mean," says Spreen.
From a global perspective, 2020 could be the warmest year since measurements began.
If you ask AWI researcher Thomas Krumpen about the reasons for the lack of ice off the Siberian coast, he too points out the high temperatures.
There had already been heat records on the Siberian mainland in the summer.
The heat reached far out to sea.
A study by the World Weather Attribution initiative showed that man-made climate change made the Arctic heat wave 600 times more likely this summer.
Normally there would be such a hot season in the region only every 80,000 years.
"One record seems to chase the next in the region"
But not only the summer was extreme, says Krumpen, the ice in the region also looked very bad in spring.
And last summer.
At that time, the so-called Northern Sea Route off the Siberian coast, also called the Northeast Passage by some, was completely ice-free for 93 days - this value had never been reached before.
"One record seems to chase the next in the region," says the researcher.
"That's really awesome."
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"There is a lot of heat in the system," says sea ice expert Dirk Notz from the University of Hamburg.
It must first be released from the sea into the atmosphere so that the Siberian coastal seas can freeze over.
"But when it starts, it really starts."
Paradoxically, the lack of ice ensures that the water can cool down relatively quickly - among other things because there is no snow on the new clods that would interfere with the transport of heat.
But Notz also knows that what is now an extreme case will soon be normal.
An analysis of 40 computer models led by him this summer showed that the Arctic Ocean will most likely be ice-free for many summers before 2050 - even if mankind should still bring about climate protection measures worthy of the name.
In the long term, the ice at the North Pole can no longer be saved.
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