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#Arctic #seaice extent has seen a minor boom, gaining 966,000 km² between Jan 5ᵗʰ and 17ᵗʰ, taking it from lowest on record to 12ᵗʰ lowest.
Does this mean a stronger pack, more capable of withstanding the 2021 melt season?
Unfortunately, things are rarely so simple (1/12)
Does this mean a stronger pack, more capable of withstanding the 2021 melt season?
Unfortunately, things are rarely so simple (1/12)
In Dec and Jan, the range of sea ice extent values between the years available is much narrower than around the end of summer and early autumn. This is because the central Arctic seas have largely filled with ice, so the variability is mostly due to the peripheral seas (2/12)
As such, small fluctuations in ice coverage, which at this time of year mostly occurs in the peripheral Arctic seas, can contribute to big changes in the overall extent values and push the rankings up substantially (3/12)
For example, Sea of Okhotsk reached the 15ᵗʰ largest extent (out of 43) this week (5-day NSIDC data). Overall, the peripheral seas have climbed from 4ᵗʰ lowest to 12ᵗʰ lowest this month. An impressive level of growth that’s likely to continue over the coming weeks (4/12)
But why might this not suggest an Arctic sea ice pack more reliant to melt this year? Part of the reason is the source of the cold air that's increasing the ice at lower latitudes, in particular, the goings on in the polar vortex
(5/12) https://twitter.com/judah47/status/1345734934485479424
(5/12) https://twitter.com/judah47/status/1345734934485479424
The #stratospheric #PolarVortex has taken a serious beating this winter, which weakened the mid latitude westerlies, promoting a -ve #Arctic oscillation. This allows bitterly cold air to spill southward and out of the Arctic (6/12).
In this instance, much of the core cold has dipped into eastern Siberia, contributing to record low temperatures, record snow in Japan and a huge increase in sea ice (as mentioned) in the Sea of Okhotsk (7/12) https://twitter.com/rgatess/status/1350865109887774721
However, this comes with a price. The cold air escaping the Arctic allows warmer air in. Surface air temperatures across the Arctic ocean remain way above average, and this is forecast to continue for the foreseeable future, with severe cold persisting across Siberia (8/12)
As the peripheral sea's lose their ice each year, there is limited benefit to them hogging all the cold. It's the central Arctic ice, hugely thinned from last summer (and preceding decades), that needs the cold to thicken up and make it more resilient. (9/12)
We can see examples of this in previous record low years. In late winter/spring of 2020, Arctic sea ice climbed to a ranking as high as 15th lowest. While the year of the record low of 2012 climbed as high as 26th lowest (17th highest) extent on record. (10/12)
Basically, processes in the #Arctic are rarely simple.
Large extent increases in the peripheral seas don't necessarily mean Arctic sea ice is recovering from the decades long loss of multi year ice and volume - it may even contribute to the problem (11/12)
Large extent increases in the peripheral seas don't necessarily mean Arctic sea ice is recovering from the decades long loss of multi year ice and volume - it may even contribute to the problem (11/12)
Plus, we still have to see what kind of whacky weather that spring and summer of 2021 throw our way (12/12)
