Melting of Arctic Ocean
The Arctic has been experiencing climate heating faster than any other part of the planet.
The thin film of frozen seawater expands and contracts with the seasons, reaching a minimum area in September each year.
The ice which remains at the end of summer is called multiyear sea ice and is considerably thicker than its seasonal counterpart.
It acts as barrier to the transfer of both moisture and heat between the ocean and atmosphere.
Over the past 40 years this multiyear sea ice has shrunk from around7 million sq. km to 4 million.
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It’s a big signal, one of the most stark and dramatic signs of fundamental change to the climate system anywhere in the world.
There has been considerable effort invested in determining when the Arctic Ocean might first become ice-free in summer, sometimes called a “blue ocean event” and defined as when the sea ice area drops below 1 million sq. km.
This threshold is used mainly because older, thicker ice along parts of Canada and northern Greenland is expected to remain long after the rest of the Arctic Ocean is ice-free.
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We can’t put an exact date on the last blue ocean event, but one in the near future would likely mean open water at the North Pole for the first time in thousands of years.
Concerns
Ice–albedo feedback:
In ice–albedo feedback by melting, ice uncovers darker land or ocean beneath, which then absorbs more sunlight, causing more heating.
This, in turn, will make the Greenland ice sheet melt faster, which is already a major contributor to sea level rise.
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The loss of sea ice in summer would also mean
Changes in atmospheric circulation and storm tracks.
Fundamental shifts in ocean biological activity.
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