(ORDO NEWS) — Oceanologists in Norway have found that the structure of multi-year sea ice in the Arctic changed irreversibly between 2005 and 2007, causing its average thickness and typical lifespan to roughly halve over subsequent years.
“Our observations show that the sea ice regime in the Arctic changed irreversibly in 2007, with the result that thick and deformed regions of ice cover began to be replaced by thinner and more uniform layers of ice.
This transition was associated with an unusually warm Antarctic summer in 2005 and 2007 and the beginning of an accelerated accumulation of heat in the waters off the coast of Alaska and Siberia,” the researchers write.
Thanks to global warming, the size of the Arctic ice cap has been gradually shrinking over the past two or three decades.
With a combination of certain weather and climatic factors, these processes are accelerated, which leads to the establishment of new winter and summer records for the decrease in ice area.
Especially often such events are recorded by satellites of NASA and other leading space agencies of the world in the last 10-15 years.
For example, the area of Arctic glaciation decreased sharply during the summer in 2007, 2012, 2015, 2016, 2017 and 2020.
During these summer seasons, the area of sea ice in the Arctic was 1-1.8 million square meters. km less than in previous decades.
Irreversible climate change in the Arctic
A team of oceanologists led by Hiroshi Sumata, a researcher at the Norwegian Polar Institute in Tromsø, has uncovered the first evidence that such abrupt glacial retreats can cause dramatic changes in the structure of multi-year ice across the Arctic as a whole.
Scientists made this discovery during the study of sea ice located on the territory of the Fram Strait, which separates Greenland and Svalbard.
At the bottom of this strait, there are many deep-water buoys that continuously monitor the properties of ice floating or located above them, including their thickness, structure, speed of movement, and other characteristics.
Sumata and his colleagues obtained data collected by dozens of such observing instruments between 1990 and 2019 while observing the state of ice in the Fram Strait.
The scientists’ analysis of this information showed that the structure of multi-year ice in the Arctic changed dramatically in 2007.
Prior to this, deformed ice 3-4 m thick dominated in the Arctic Ocean, and after that ice, whose thickness was about 1-1.5 m, began to dominate.
Similarly, the average life span of ice changed dramatically – it fell from 4.3 years up to 2.7 years.
The reason for this, according to oceanologists, was that in 2005 and 2007 the Arctic experienced two record warm summer seasons, during which a significant part of the seas off the coast of Alaska and Siberia was freed from ice.
This accelerated the flow of heat into the waters of the Arctic Ocean and irreversibly changed its heat balance, as a result of which perennial ice became thinner and shorter-lived, the scientists concluded.
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