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– Actually, I would say this is a new record level. It’s very close to the record low in 2012, which was an unusually extreme year with strong storms breaking up the sea ice, says Michael Tjernström, a climate researcher and professor of thin-layer meteorology at Stockholm University.
The record low in 2012, in turn, approached the previous record year of 2007, it adds.
– It was 2007 when we really opened our eyes to this and wondered if it could really be that bad with the ice in the Arctic. Since then, it has continued, no year after 2007 has had more ice than any year before 2007. That was the turning point, says Michael Tjernström.
Clear direction
But preferably you don’t want to talk about record levels. It is the long-term trend that is important, and while there are large variations from year to year, the direction is clear: Arctic sea ice is declining at a rapid rate, explains Michael Tjernström.
– Above all, it is the ice mass that disappears. It decreases significantly faster than the surface, as the ice becomes thinner and thinner. Although the entire Arctic basin still freezes over each winter, the new ice becomes thinner after years like this, making it a process built up over decades.
Earth’s cooling system
TT: What is the problem of ice shrinking in the Arctic?
– The Arctic, and also Antarctica, are the parts of the planet that counteract warming. Therefore, they play a crucial role in the Earth’s climate. Also, it’s about the people who live there. And about the animal species and biotopes that have nowhere to go other than the freezing climate, it is part of the biological diversity that is lost, says Michael Tjernström.
The US National Ice and Snow Data Center has been monitoring ice by satellite for more than 40 years. At this time of year, the extent of Arctic ice reaches its minimum, as the ice stops melting after the summer and freezes again when the winter cold returns.
The thickness of the ice can be measured with a submarine.
Measuring the distribution of Arctic ice is relatively easy with a satellite and the NSIDC (National Snow and Ice Data Center) has done it regularly for 42 years. But to understand more about how ice develops, researchers must also know how thick the ice sheet is. This can be done by drilling deep holes, but it is a time-consuming method and cannot provide data over larger areas. Therefore, researchers have developed methods to use submarine-mounted inverted sonar.
Such underwater measurements have shown that the average thickness was about three meters in the 1970s, and that it has recently decreased to about two meters.
Now there are also methods to measure thickness with satellite.
Source: polarisen.se (run by the University of Gothenburg)
