Saturday, 28 January 2017

A new Arctic feedback

A new Arctic feedback (?)

Arctic Sea Ice Blog

19 January, 2017


Quote from the latest PIOMAS update (10 days ago):
There's just no end to this run we have had with anomalously warm temperatures, and storms blowing in from the Atlantic.
As we speak, a very powerful winter storm is battering the ice pack on the Atlantic side of the Arctic, as shown on this SLP map (source):


Lowest pressure was probably reached yesterday at 957 hPa, but it's still raging at 958 hPa right now. Remember, the GAC-2012 clocked in at 962 hPa, and the series of powerful storms we saw last August bottomed out at 968 hPa. Storms tend to be stronger during winter.
In the short term this might actually increase sea ice extent, as strong winds will be pushing out the ice towards the Atlantic, but in the longer term it will probably be detrimental to the ice pack, as a lot of the ice being pushed out is older and thicker. The storm and the moisture it brings with it, will also cause more snowfall, insulating parts of the ice pack so that the ice grows thicker at a slower pace, and thus be thinner than it could have been when the melting season starts.
The ECMWF forecast is showing another strong storm forming 9-10 days from now, but that's very far out, and so the forecast can change. But the storm we're seeing right now (I briefly mentioned it in this previous blog post), was also forecast 10 days ago and then came about. We'll have to wait and see what happens.
Now, what is causing all these storms and all that moisture to be transported all the way to the Arctic? We saw the same thing during last year's winter, but this time it's even worse. It might have to do with all the heat that the recent El Niño brought with it, but previous El Niños didn't seem to have such a marked effect. Perhaps it's something else, another reaction to Arctic sea ice loss, some sort of vicious cycle.
Yesterday this video was posted on Peter Sinclair's ClimateCrocks blog, showing an interview with Dr Jennifer Francis (Rutgers University)
at the AGU 2016 Fall Meeting this past December:



Another effect of this possible feedback is more clouds during summer, shielding the ice from the Sun's rays. But as we saw during last year's melting season, this didn't help much (except for preventing new sea ice extent/area records). That's probably because heat doesn't just enter the Arctic via the atmosphere, but via ocean currents as well.


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