A quite spectacular event took place during the past two weeks, and if it had continued for a while longer, I'm sure it would've been reported widely. It's something I've semi-jokingly alluded to when setting up this blog back in 2010, in my third blog post called Dire Straits, and a partial answer to the question commenter fredt34* asked at the time:
The big hole opening in East Greenland re-activated my interest for this question: will we see Greenland being circumnavigable this year? If not, when?
That was July 23rd 2010, and now a little over 8 years later, we have almost seen it happen: a corridor of open water between Fram Strait and the Lincoln Sea (where Nares Strait starts). Here's an animation of NASA EOSDIS Worldview satellite images showing what has happened during the past two weeks, ending yesterday (click for a slightly larger version):
And here's the animation with only the first and last images, two weeks apart:
Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:
A new year, a new trend line, and if you watch the above graph closely, you'll see how it dips right under the 2013 trend line at the end of January. This means that 2018 now has the second lowest sea ice volume on record, according to the PIOMAS model. A monthly total of 3005 km3 was well below the 2007-2017 average of 3195 km3, which means 2018 also extended its lead over most other years. Last year, however, January volume was 50 km3 lower still and so that gap has grown slightly bigger again. Given how volume fared during the first few months of 2017, it doesn't look like that 1407 km3 gap is going to be bridged any time soon.
Here's how the differences with previous years have evolved from last month:
Wipneus' version of the PIOMAS graph more clearly shows how the 2017 trend line (light red) goes off even further on a tangent:
Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:
Volume increases for December in the last 10 years aren't all that far apart, ranging from 3500 to 4000 km3 (rounded off). This year was on the lower side of that range, with 3547 km3. Only 2010 and 2014 were lower than that, just barely. This means that 2017 ends the year in third spot. The gap with 2012 has been reduced some more, from 733 to 497 km3, and the quickly widening gap with 2016 has stopped widening for now, going from 1482 to 1340 km3.
Here's how the differences with previous years have evolved from last month:
On Wipneus' version of the PIOMAS graph you can see how that difference with 2012 has become smaller again since September (red is 2017, purple is 2012):
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.
Lately the focus has been on the Beaufort Sea where a high-pressure area has caused the ice pack to crack on a massive scale, even earlier than in previous years, with ice being transported away from the North American coast (see here). But such a large and persistent high-pressure system is bound to have an impact elsewhere in the Arctic as well, so here's an overview of what's been happening on the Atlantic side of the Arctic (and a bit of Siberia as well).
As we saw in the recent 2015/2016 Winter analysis blog post, the Arctic experienced an incredibly warm/non-cold winter:
On top of that, a string of cyclones crossed the Atlantic and veered off to the Arctic, causing increased ocean heat flux on the Atlantic side of the Arctic, which explains why the Barentsz Sea and Greenland Sea have been anomalously low in sea ice extent all winter. They're still extremely low:
In fact, Svalbard could almost be circumnavigated several times, with at one point very close to ice-free conditions from Svalbard all the way to Franz Josef Land.This graph from the PolarView website shows how anomalously low sea ice levels have been in the Svalbard region:
I think this winter is going to get studied like crazy, for quite a while. It’s a very interesting time. Jennifer Francis, Washington Post
The extraordinary temperature anomalies in the Arctic since the start of the year haven't gone unnoticed in quite a few media outlets, and I apologize for not having joined the fray of actuality. On the other hand, context trumps actuality, as we need to compare to previous years and get a feel for what this prelude to the melting season may mean. In that sense, I'm early with this year's winter analysis (compared to last year).
Let's start studying like crazy, shall we?
It's a lot of text and images, so if you're feeling a bit tl;dr-ish today, skip to the conclusion at the bottom of the page.
Surface air temperature
Here are the monthly temperature graphs for November-February in the Arctic Circle, from 2005/2006 to the past winter, based on the NCEP reanalysis dataset:
Last November saw the highest average monthly temperature in the 2005-2015 record, followed by a lower December, relatively speaking. Things then get a little bit crazy after the turn of the year, with the January 2014 record getting broken by almost 3 °C! February isn't far behind either, almost 1.5 °C higher than the already 'warm' February of 2014. This is unprecedented.
To see where temps were least low, I've created average temperature maps using the Daily mean composites page from NOAA's Earth Science Research Laboratory website, comparing the 2015/2016 freezing season to those preceding the years with the lowest minimums on record (click for a larger version):
A week has passed by since the melting season ended and the minimum on all sea ice extent and area graphs has been reached. During this week I've been collecting images that show various aspects of this year's melting story, which will be accompanied by short explanations/interpretations.
Such an overview must inevitably start with an image showing the shape of the ice pack, and the University of Bremen has put up a great sea ice concentration map that also shows the ice pack outlines at the end of record melting seasons 2007 and 2012, as well as the 1981-2010 average:
2012 (cyan) clearly had less ice, but there are a couple of spots where this year had less ice than in 2007 (red). The September graph for ADS-NIPR/JAXA sea ice extent shows how close 2015 came to the lower years, slipping right below 2011 and ending in 3rd position:
The same can't be said of the Cryosphere Today sea ice area graph. 2015 ended relatively low there too, but at the top of the bundle of trend lines, in 6th position:
Wipneus, creator of many graph and animations, has posted another gem over on the Forum.
The animation he uploaded to Youtube becomes really interesting after the end of May, when the transport through Fram Strait (one of the reasons that made the 2007 melting season so spectacular) almost completely stalls for much of the rest of the melting season:
Even though it's obvious that the lack of movement and transport was the defining theme of the 2014 melting season, it's still amazing to see it expressed so clearly in this animation. That trunk of ice that always protrudes through Fram Strait into the Greenland Sea, simply vanishes in July.
In October transport picks up again, and in the past few weeks it has been relatively strong. This is somewhat interesting because compared to 2013 a lot of the volume difference is situated close to Fram, as can be seen on this 2014-2013 thickness difference map produced by... wait for it... Wipneus:
If transport keeps up, the difference in volume (with 2013) might become smaller, but we'll have to wait and see what PIOMAS reports. In 2015.
And so, in advance, I wish everyone a happy, healthy, succesful and sustainable New Year!
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