Late Winter Arctic Cracking Event, Rapid Ice Motion Resulted in Loss of Thick Ice

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(Image source: JAXA)

A major early season Arctic sea ice cracking event has mostly run its course. This unprecedented and much sooner than usual ice break-up left scars all over the Arctic. Scars that are likely to leave the ice in a much weaker condition as the current melt season ramps up. The most obvious are visible as cracks and leads through even the thickest ice. But equally concerning is a very rapid transport of thick ice out of the Fram Straight over the past few weeks.

Export of ice through Fram is usual, regardless of season. What is unusual is that this particular event occurred with such high velocity that it rapidly depleted a large region of the Arctic’s remaining thick ice. The acceleration of sea ice motion during the recent cracking event pushed enormous sections of ice to the north of Greenland, ice that had previously been part of the swiftly dwindling multi-year ice pack, out into the North Atlantic where it is destined to collide with warm ocean currents and melt out. Looking at an animation of sea ice since mid-February, it looks as if the thick ice is being squeezed out of the Arctic like toothpaste is squeezed out of its tube.

Multi-year ice (MYI) has been in rapid decline ever since the year 2000 and is now at lowest levels in any historic record. This ice is also the Arctic’s thickest, its freshest and its most resilient to melting. MYI decline, cracking and rapid export through the Fram Straight is leaving it more and more weakened for the upcoming melt season. This depleted state, combined with the fact that most of the remaining Arctic is now covered in first and second year ice means that the sea ice will be far more vulnerable to weather, wind, waves, sunlight and heat come summer.

It is the year after year decay of the thick, multi-year ice that is just one factor making ice ever more vulnerable. Ever increasing ocean heat content, decreasing spring snow cover, loss of Arctic reflectivity or albedo, increasing expanses of dark, sunlight and heat absorbing water, increasing Arctic greenhouse gas feedbacks, changes in the water column due to methane hydrate destabilization, and ever-increasing human greenhouse gas emissions are all factors pushing the Arctic toward more rapid transition.

Links:

http://www.ijis.iarc.uaf.edu/cgi-bin/seaice-monitor.cgi?lang=e

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