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What does no Arctic sea ice mean for the rest of the world?

Hamna Humail

16th Nov, 2020. 04:49 pm
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Arctic sea ice
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An ice-free Arctic Ocean throughout summer is expected by scientists in the next few decades. Due to the exceptional summer heat wave which roiled the Russian Arctic, this prospect seems much more likely.

The Laptev Sea, which lies in the northern region of the Siberian coast, is usually a factory for new sea ice but it reached a record low in 2020.

The Arctic sea is the brightest natural surface on the planet as it is covered in snow most of the year. It reflects about 80% of the solar radiation which hits it back to outer space.

The ocean it floats on is the darkest natural surface on the planet which absorbs 90% of incident solar radiation. Any changes in sea ice cover impacts how much sunlight the planet absorbs and how fast it warms up.

Every year a thin layer of the Arctic Ocean freezes forming sea ice. This melts again in spring and summer but some of the sea ice stays which is known as multi-year ice.

The multi-year ice is thicker and more resilient than the sea ice but as the Arctic climate warms, the multi-layer is under threat. It has shrunk by about half in the last 40 years.

Scientists expect the world will see an ice-free Arctic Ocean throughout the summer in the next few decades.

Shutting down the sea ice factory

The top meter of the oceans have about the same thermal capacity as the whole of the atmosphere. The oceans accumulate heat slowly over the summer and release it equally slowly during winter.

The Laptev Sea of the Arctic Ocean is a factory for new sea ice in autumn and winter as air temperatures drop to freezing temperatures. The new ice which is formed is carried westward by persistent offshore winds in a kind of conveyor belt.

Ice in the Laptev Sea reached its lowest record in 2020 with no formation of new ice throughout October. The exceptional summer heat wave across Siberia resulted in heat accumulating in the adjacent ocean, which is now delaying the regrowth of sea ice.

A rapidly changing Arctic is a global cause for concern. The Greenland Ice Sheet, largest ice mass in the Northern Hemisphere, is currently contributing to sea levels rising and has enough ice in it to raise the global sea level by 24.2 feet (7.4 meters).

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