It goes down in the books as the second lowest ice minimum in over 40 years.
Researchers present the figures for the annual minimum size of Arctic sea ice. On September 15, a size of 3.74 million square kilometers was noted. That is, by the way, quite worrying. Because this includes the second lowest sea ice minimum in 42 years.
Maximum to minimum
Each year, the amount of sea ice resting on the Arctic Ocean varies. During the spring and summer, some of the sea ice melts, to freeze again in the fall and winter. It results in an annual sea ice minimum and an annual sea ice maximum. The minimum amount of sea ice is measured towards the end of summer (September), while the maximum amount of sea ice is recorded towards the end of winter (March).
The image below shows the amount of Arctic sea ice on September 15. So it concerns an area of 3.74 million km2. The orange line shows the average size from 1981 to 2010 on the same date.
Minimum Arctic sea ice size in 2020. Image: National Snow and Ice Data Center
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The listed minimum is quite worrisome. It is quite rare that the sea ice minimum dips below 4 million square kilometers. Researchers also saw this happen in 2012, when a record-breaking sea ice minimum of 3.39 million square kilometers was recorded. The fact that it is now hit again, is mainly due to temperatures that are about 8 to 10 degrees Celsius higher than average. “It was just really hot in the Arctic this year,” says researcher Nathan Kurtz. “Moreover, the melting seasons started earlier. And the sooner the melting season starts, the more ice you usually lose. ” Notably, after September 8, the ice began to melt away rapidly and then reached its seasonal minimum size a week later.
Comparison
If we compare the state of this year with previous years, it is striking that compared to 2012 there is slightly more ice on the Beaufort Sea. Slightly less ice can be found on the Laptev Sea and on the eastern part of the Greenland Sea. It is also noticeable that the fourteen lowest minima have all occurred in the past fourteen years. Moreover, it appears that the minimum size was reached one day later than the average in the period between 1981 and 2010. Normally the researchers note the minimum size around 14 September. But that is getting later nowadays. In 2018 it even dropped nine days longer to wait. The minimum date of September 23 of that year is therefore one of the last dates ever. The reason it fell a little later in 2018 seems to be due to a southerly wind from the East Siberian Sea, which blew warm air into the area.
Here you can see the extent of the sea ice in different months and years. The year 2020 is represented by a blue line.
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Meanwhile in Antarctica
While the Arctic sea ice has reached its minimum size, the Antarctic sea ice is heading towards a sea ice maximum. Remarkably, the size of the sea ice in Antarctica is now well above average. That is not exceptional, by the way. In 2014, the Antarctic sea ice even broke all records; At the end of the winter, there was no less than 20.1 million square kilometers of sea ice around the continent. That is nearly 1.5 million square kilometers more than the average found around Antarctica in the period between 1981 and 2010 at the end of winter. The fact that there is also a lot of sea ice in Antarctica this year is striking and illustrates the enormous variability with which we have to deal with this system. However, we still have to be patient. Because the true annual maximum for Antarctic sea ice is usually written in late September or early October.
This year’s figures indicate that there is less and less sea ice in Arctic waters. Although the reported 3.74 million square kilometers appears to be the lowest size of the year, the researchers are still cautious. That’s because a changing wind or melting later in the season can still change the minimum size. Scientists will therefore publish a full analysis of the Arctic melting season in October.
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