The melting sea ice falls to historic lows by the beginning of April

The melting sea ice falls to historic lows by the beginning of April

The melting sea ice falls to historic lows by the beginning of April



  • As of April 9, the Arctic had about 13.6 million square kilometers (5.3 million square miles) of ice coverage, standing firmly below any other year registered for the same time of year, and almost two weeks before the previous records of April. In 2017 and 2018.
  • The implications of such a low extent of sea ice for this time of year are for scientists. However, predicting seasonal ice melting is very difficult, and changes in Arctic climate could cause the early melting to stop, or even reverse to some degree.
  • Two new studies of the Arctic are also worrying. The researchers found that between 1998 and 2017, seventeen percent less ice left the seas of the shallow continental shelf (sea ice nurseries) to reach the Central Arctic Ocean and the Fram Strait. This loss in the ice that is transported could have serious implications for the melting of Arctic sea ice and also affect biodiversity.
  • A second study found that the increase in air temperature in the Arctic is driving change throughout the ecosystem. Warmer temperatures are affecting the growing seasons of forests and tundras, increasing forest fires, increasing rain and snow, and melting ice, changing the region from its 20th century condition to an unprecedented state.
An aircraft examines the early melting of Arctic ice. Image of Esther Horvath / AWI.

When the Arctic sea ice reached its maximum winter extent on March 13, the world paid little attention. 2019 ended up tied for the seventh lowest place in winter in the 40-year satellite record, a forgettable statistic in a period of consecutive record breakers.

But as scientists pointed out at the time, the Bering Sea, which separates Alaska and Russia, was abnormally free of ice. In the weeks since the overwhelming headlines in March, the Arctic has surprised almost everyone: the extent of sea ice has plummeted by more than one million square kilometers (386,000 square miles) in an unusually sharp decline.

The Arctic now has about 13.6 million square kilometers (5.3 million square miles) of ice coverage, which puts us firmly below any other year for the same date, and almost two weeks before the records of early April in 2017 and 2018. As we head to The summer season melts, the implications are worrisome.

2019 sea ice extension in the Arctic from April 9, compared to the record year 2016, 2017 and 2018. In April 2012, the ice extent was well above what it is today, but 2012 is still the lowest recorded summer ice extent. Image courtesy of NSIDC
The Yukon River meanders through the western interior of Alaska. This year extremely high temperatures were recorded in Alaska for this time of year, around 20 degrees Fahrenheit, warmer than normal in March, which means an earlier entry of warmer fresh water to the Arctic Ocean from the Yukon and other currents, contributing to a faster melting of sea ice. Image of Todd Paris

Although the sea ice extent of the final summer is largely dictated by weather patterns, we are more than one million square kilometers below mid-April 2012; That year experienced the smallest extent of summer sea ice to date, and we have already dropped below 2007, 2011 and 2016 for this time of year, which ranked second, third and fourth lowest for minimum extensions September, respectively.

"It's been a quick loss of ice," says Walt Meier, principal research scientist at the National Snow and Ice Data Center. "Most of the loss of ice in the past [two weeks] It has been in the Bering Sea. That region was largely free of ice until the beginning of March, [then] We had a couple of weeks of growth where the Bering Sea extension increased a lot. But … the ice is very thin, so it did not take much to break it and / or melt it. "

What is happening in the Bering Sea at this time is emblematic of much greater changes in the global Arctic. Two studies published in recent weeks offer a disconcerting look at the past, present and future of the vulnerable region.

When researchers at the Alfred Wegener Institute compiled satellite data from 1998 to 2017, they found that 17 percent less ice from the shallow seas off the coast of Russia, including Kara and Laptev, is arriving at the Fram Strait (located between Greenland and Svalbard) where the ice comes from The Arctic to the North Atlantic.

A researcher practices ice sampling. Image of Stefan Hendricks / AWI

Those shallow coastal seas are considered a kind of sea ice nursery, and produce a large amount of sea ice that, in past circumstances, would eventually make its way to the vast Central Arctic Ocean, then through Fram. Although these seas continue to produce the same amount of ice, it is increasingly melting before it can leave the coastal zone.

Due to this thinner and lighter ice, the Transpolar Drift, the current that leads from the seas of the platform to the Central Arctic Ocean, is accelerating. Although this new trend led some to speculate that an increase in speed could compensate for the decrease in the ice sheet, since the remaining ice moves faster, Thomas Krumpen, the study's lead author, says that this has not been the case. Young ice is still melting too fast for a faster stream to make up the difference.

The acceleration of the Transpolar Drift is not only affecting the ice, but possibly also affects the Arctic biodiversity. Many rivers flow into the Arctic Ocean in shallow seas, which means that the ice that forms there is rich in nutrients and sediments, as well as pollutants. Under normal conditions, these ice-covered particles are transported from coastal areas to the Central Arctic Ocean. But if the ice does not survive after leaving the nursery, those nutrients do not reach the distant species that depend on them, and the contaminants do not disperse either.

A simplified graph showing the transpolar drift of the shallow seas of the Russian platform towards the Central Arctic Ocean and from the Fram Strait to the North Atlantic. Image courtesy of AWI.

"You would release nutrients, but also things like microplastics, locally instead of in a larger area," concludes Krumpen. "The consequences of that we do not know yet."

Researchers know that at some point in the not too distant future, the Arctic Ocean will experience summers without ice. Most set that point in time to be around 2030 or 2040, but some say it could get there sooner. When that happens, the material trapped in the sea ice can only travel up to eight or nine months, the shelf life of the seasonal ice before it melts.

"A summer without ice basically cuts off all types of transport," explains Krumpen. "That's not surprising, what we did not know is that this is already happening." The seas of the Russian platform are already losing connection with the Strait of Fram. "

Scientists descend to the Arctic Ocean to take samples of ice. Image of Ruediger Stein / AWI

Another study published last week in Environmental research letters, reveals that the increase in air temperature in the Arctic is the key component that drives change throughout the ecosystem. In the summer months, the Arctic is warming 1.7 times faster than the rest of the northern hemisphere. In the winter months, that jumps to 2.8 times faster.

These warmer temperatures are affecting the entire north: the seasons of forest and tundra growth moving northward, the increase in forest fires in the tundra, the increase in rainfall and snowfall and, of course, the melting of the ice. In addition, as other studies have shown, these broad changes in the ecosystems of the entire region in turn affect wildlife.

"The Arctic system is moving away from its 20th century and in an unprecedented state, with implications not only within but beyond the Arctic, "says lead author Jason Box of the Geological Survey of Denmark and Greenland.

Quotes:

Box, Jason E., et al. Key indicators of climate change in the Arctic: 1971-2017. Reign. Res. Latvian. 2019; 14 (045010).

Krumpen, Thomas, et al. The warming of the Arctic interrupts the Transpolar Drift and affects the long-range transport of sea ice and rafting material. Scientific reports, 2019; 9 (1).

I think this works. It is not entirely correct to say that 17 percent less reaches the CAO. It is 17 percent less than it reaches the Fram, which serves as the final point in the Arctic.

Image of the banner: drilling and sampling of Arctic ice. Image of Mario Hoppmann / AWI.

REACTION: Use this form to send a message to the author of this publication. If you want to post a public comment, you can do it at the bottom of the page.

Arctic animals, climate, climate change, climate change and conservation, climate change and extreme climate, climate change and forests, climate sciences, earth sciences, global warming, climate change impact, monitoring, oceans and climate change, research, satellite data, satellite images, science


Source link