I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2006-2009. The IJIS graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a good explanation of what sea ice extent is in their FAQ.
September 9th 2010
I ended my last SIE update with a picture of a seesaw with a little girl sticking out her tongue at a big Texan guy. Little did I know. As usual when I say something about the Arctic the opposite happens. Instead of seesawing and stumbling, the Arctic has averaged more than 50K square km per day since the last SIE update. That is very high for this time of the year. Instead of a seesaw I should have opted for a slide as a metaphor for the current extent decrease.
With the latest reported extent decrease of 49,844 square km (before revision) the total sea ice extent has just dived under the 5 million mark. That's still a bit of a magic number (for the time being). It's only natural to start speculating if 2008 can still be overtaken, but I have a feeling the finish line is too close for that to happen. More about this towards the end of the post, let's look at some statistics first.
I had all the years from 2006-2010 in my spreadsheet and figured that would be enough for this year's race. For all these weeks and months I was too lazy to adjust my spreadsheet. But commenter Jon Torrance brought to my attention that 2005 had quite an interesting finish, so I made the effort, added its IJIS extent data to my spreadsheet and show the numbers for these last few SIE updates I'm doing.
The current difference between 2010 and the other years is as follows:
- 2005: -665K(15,623)
- 2006: -958K (13,784)
- 2007: +564 (14,688)
- 2008: +238K (38,219)
- 2009: -353K (15,180)
Between brackets is the average daily extent decrease for the month of September until each year's respective date of minimum extent. 2010's average daily extent decrease for September is currently 44,004 square km per day.
If 2010 loses as much sea ice extent as...
- 2005 did after this date it will bottom out at 4.65 million square km.
- 2006 did after this date it will bottom out at 4.82 million square km.
- 2007 did after this date it will bottom out at 4.82 million square km.
- 2008 did after this date it will bottom out at 4.95 million square km.
- 2009 did after this date it will bottom out at 4.90 million square km.
Here's the IJIS sea ice extent graph:
In the meantime Cryosphere Today sea ice area is dropping dangerously close towards the 2007 and 2008 minima. Let me add to that though that 2007 reached its minimum on the 8th of September, 2008 on the 9th and 2009 on the 10th. So same story here: Is there enough time left for 2010 to get rid of another 100-150K square km and be one of the champions? 2007 bottomed out at 2.92 million square km, 2008 at 3.00 million square km. Here's the data.
The anomaly compared to the 1979-2008 mean has dropped some more and currently stands at -1.624 million square km, mostly caused by a continuing decrease in the Arctic Basin (most other regions have bottomed out). Here's the graph, looks like we're having a double dip this year:
Because area and extent are both dropping our CAPIE (Cryosphere area per IJIS extent) graph is still showing a very low compactness percentage of 61.86%. This is most probably due to the spreading out of the ice near Svalbard and around the North Pole. This year the freeze-up might start before any serious compaction occurred, which paradoxically means that while the extent was third lowest in the satellite era, it might still be artificially high. What this means for next year's ice pack, remains to be seen and is something I'm sure we will all be speculating about. Here's the CAPIE graph:
So why do I think the ride down the Arctic slide might be shorter than anticipated after all those days with high extent decreases?
My End Zone series, though very limited and amateurish in scope and analysis, led me to believe that atmospheric patterns play a crucial role in determining the end date of the melting season. As long as that Arctic Dipole Anomaly, with its high over the Beaufort and its low over Siberia, keeps churning the ice towards Fram Strait and the ice moves fast enough to postpone the moment of freezing temperatures finally getting a hold. That's why one of the very first things I look forward to before lunch is the PIPS ice displacement map. The length and direction of its arrows tell us a lot about the transport towards the warmer waters beyond Svalbard.At this period of the melting season it is a good indicator of extent decrease.
But all this is determined by atmospheric patterns and the position of high- and low-pressure systems over the Arctic. So, what is the weather forecast for the coming 10 days according to the ECMWF forecast model? Well, it's not looking too good. The high over the Beaufort will be pushed out of the playground in the coming next two days and low-pressure systems will be fully dominating the Arctic. That spells the end of the Arctic Dipole Anomaly:
In 2008 and 2009 this was the referee's final whistle.
Of course those big cyclones might wreak some additional havoc in the weakened ice pack, especially the rotten parts, and thus lengthen the melting season somewhat with lower daily extent decreases. And we mustn't discard sea surface temperatures either. I have been reading here and there that these SSTs play a big part in prolonging the melting season, now and increasingly in the future. Here's an animation of September anomaly maps by EORC/JAXA compared to previous years and you can see that this years is pretty 'hot':
At the moment I think the melting season might end in 3-5 days. But nothing in the Arctic is a dead certainty, hombres.
TIPS - Other interesting blog posts and news articles concerning the Arctic and its ice:
ClimateProgress has two very interesting articles on Arctic sea ice. One for the current situation: Arctic non-shocker. And one for the past (dealing with all those rehashed news articles that suddenly pop up): Major analysis finds “less ice covers the Arctic today than at any time in recent geologic history”. A third piece has emerged two days ago explaining how the Arctic death spiral is continuing.
Patrick Lockerby has written another update about his ice island: Petermann Ice Island - Now There Are Two.
It's not just Norwegians sailing in the Arctic. Here we have some Finns: "Today, S/Y Sarema crossed the Arctic Circle during her southbound voyage towards Halifax. This means that we have finally put the fabled Northwest Passage behind us."