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Climate crisis: warmer temperatures and less ice lead to a vicious circle in the Arctic

2020-12-09T22:24:17.182Z


Heat and fires in Siberia and an extreme sea ice minimum in summer - the climate in the Arctic was extreme in 2020. Researchers warn of increasingly intensifying effects.


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Iceberg off Greenland: higher temperatures lead to less ice - and vice versa

Photo: Ulrik Pedersen / NurPhoto / Getty Images

From October 2019 to September 2020, the twelve months were the second warmest the Arctic has ever experienced since measurements began in 1990.

Fires, high temperatures and loss of ice had a significant impact on the climate in the far north, writes the American weather and oceanography authority Noaa.

In its annual report on the Arctic region, the agency examined how the world, once frozen over many months, is changing.

“Overall, the matter is clear.

The transformation of the Arctic into a warmer, less frozen and biologically modified region is well underway, ”said Alaska-based climatologist Rick Thoman, co-editor of the report.

Extremely little summer sea ice

One of the problematic observations is that air temperatures have been at least 1 degree Celsius above the mean value from 1981-2010 in nine of the past ten years.

In the past six years, arctic temperatures have exceeded all previous records, according to the Noaa.

This has led to a cascade of changes in the ecosystem and its climate.

Icon: enlargePhoto: NOAA

Among other things, the sea ice in the Arctic has retreated extremely over the summer of 2020.

In September the annual minimum reached the second lowest value since satellite records began.

Only in 2012 did the sea ice retreat further after a cyclone damaged the sea ice cover.

The average extent of the Arctic sea ice over the whole of September 2020 was 3.9 million square kilometers.

In 2005 it was 5.6 million square kilometers.

According to the current evaluation, the annual ice minimum in September has decreased by around 13 percent over the past ten years compared to the mean for the years 1981 to 2010.

Icon: enlargePhoto: NOAA

“When we first published the report 15 years ago, I wrote about how low the sea ice extent was at the time.

But I would exchange the values ​​from then for what we see today, ”Donald Perovich, a geophysicist at Dartmouth University, told Reuters.

Dangerous vicious circle

The quality of the ice cover also decreases.

In the past ten years it has changed from an older, thicker and overall stronger to a thinner, younger and more unstable mass of ice.

This also causes the Arctic waters to warm up, as sunlight is now being absorbed by the ocean instead of reflecting off the ice surface.

Every ten years, August temperatures in the Arctic seas rose by about one degree, the report said.

The Chukchi Sea in northwest Alaska is particularly affected.

The only exception is the northern Barents Sea north of Norway, with sea water temperatures tending to fall.

The researchers warn of a vicious circle: Higher temperatures lead to less ice, which in turn means that less sun is reflected and sea temperatures rise, which in turn affects the climate of the air and so on.

"We're starting to see more of this feedback," Perovich said.

Research on the Arctic is now "more than an intellectual task to understand nature.

These changes have consequences for the people who live today. "

High temperatures, drought, fire

The warmer water and the rise in temperatures in the air are also causing glaciers to shrink.

From September 2019 to June 2020, the ice cover in Greenland again lost more ice than the average between 1981 and 2010. "Glaciers and ice sheets outside Greenland also continued the trend of significant ice loss," said the Noaa.

This applies particularly to Alaska and Arctic Canada.

Water that flows from glaciers, i.e. land masses, into the sea, contributes to the rise in sea levels.

For a rough classification: There is so much water stored in the snow and ice cover of Greenland that it would raise the global sea level by 7.4 meters.

In Eurasia, too, the climatic changes in June resulted in the lowest snowpack since records began in 1967. Overall, annual snowpack on land has declined at a rate of 3.7 percent per decade since 1981 - with an even steeper decline of 15 percent per decade Decade for the period from May to June.

Icon: enlargePhoto: NOAA

The record heat and drought in Siberia was also noticeable this year.

It led to a violent season of fire and delayed the refreezing of the Arctic Ocean.

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Source: spiegel

All tech articles on 2020-12-09

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