During the melting season 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 2005-2010. NSIDC has a good explanation of what sea ice extent is in their FAQ. I also look at other things like sea ice area, concentration, volume, temperature and weather forecasts, anything that can be of particular interest. Check out the Arctic sea ice graph webpage for daily updated graphs, maps and live webcam images.
August 13th 2011
I took my eyes off the ice for two days, which was a grave mistake. Just like life, the melting season goes slow, but lightning fast at the same time. No time for distraction. I've been catching up today, had an intense look and read to get that gut feeling back, and as always it is difficult to express how fascinating the Arctic and its ice are.
I had essentially ruled out a new record minimum extent last week, stating that 2011 would only have a chance left if by August 10th sea ice extent would be within 200K square km of 2007. Even though this didn't come about, I left the door ajar, as the weather seemed to be shaping up for increased declines. I'll quote myself from a comment on August 9th: "If 2011 manages to get within 150K of 2007 by August 20th, the race is on again."
I still stand behind that. At the same time must admit I had expected extent to go down a bit faster. Not that things were going slow for this time of year, but I'd (wishfully) thought we'd see a century break or two. There's still 7 days to go until August 20th, and the difference between 2007 and 2011 is somewhat smaller, but still significant. At the same time 2011 hasn't budged when it comes to sea ice area, and our CAPIE graph is signalling major divergence of the ice pack.
This divergence is taking place on the Pacific side of the Arctic and can be seen on sea ice concentration maps and on satellite images (through the many clouds). Where holes in the ice pack were the most striking feature of last year's melting season, I would say this year is increasingly characterized by a sea of slush puppy ice in the Beaufort and East Siberian Seas.
Greyish, brown, spread out like butter on warm toast. Despite high SSTs, high air temperature, battering winds, waves and sun, this rotten ice is still somehow managing to keep the extent from dropping through the floor. For how much longer, I wonder.
If 2011 is to set new records, it'll have to do so on this battlefield where the Arm of multiyear ice held out till the very end. That Arm is not there this year, or at least it's not as muscular. We'll see what the arm-wrestling brings this year.
Sea ice extent (SIE)
Here's the current IJIS SIE graph:
Not much has changed really since the last SIE update, except that - as I expected last week - the 6 million mark has been passed. 2011 has nibbled a bit at 2007's lead, but is still more than 400K behind. It has however maintained and even increased its lead over the other years. 2007's extent decrease is leveling off in the coming week, so perhaps 2011 can creep a little bit closer. Like I said, depending on the slush puppy and weather patterns (more on that below).
The current difference between 2011 and the other years is as follows:
- 2005: -497K (-45,000)
- 2006: -669K (-37,697)
- 2007: +406K (-57,041)
- 2008: -464K (-70,333)
- 2009: -548K (-48,654)
- 2010: -316K (-51,736)
Between brackets is the average daily extent decrease for the month of August. 2011's average daily extent decrease for August is currently -61,068 square kilometers. Here's the daily average in previous years from August 1st to 12th:
- 2005: 60,156
- 2006: 53,880
- 2007: 79,518
- 2008: 81,563
- 2009: 48,333
- 2010: 64,844
Sea ice area (SIA)
Like I said in the intro, 2011 is still deep into record territory when it comes to Cryosphere Today sea ice area. Unfortunately today's number hasn't been reported yet, but 2011 has a lead of 118K square km over 2007 and 320K square km over 2008 (edit: the number came in just as I had finished the blog post; 2011 is 37K square km ahead of 2007, and 280K square km ahead of 2008). If in the next 4 weeks we see a decrease of 650K square km or more, there will be a new record SIA minimum. Here's the graph from Piotr Djaków:
The Cryosphere Today SIA anomaly graph is still as low as it ever was (and the Antarctic SIA has gone negative again, so maybe more interesting news on this in the coming weeks):
As we can see on the Regional Graphs page, the SIA has been decreasing steadily practically everywhere (Arctic Basin and Canadian Archipelago), except in the East Siberian Sea and the Greenland Sea where the ice is being spread out and pushed towards Fram Strait respectively.
Cryosphere Today area per IJIS extent (CAPIE)
The trend line on our CAPIE graph is very close to hitting a new low, which shows us that the ice pack is spread out quite a bit. In theory there's still a lot of room for extent to decline, if atmospheric patterns would start to compact the ice pack. I was expecting some of that compaction in the past week, but apparently there is still more divergence than compaction going on. Here's the graph:
The reason I expected more compaction and thus bigger daily extent drops, was the dominance of a big and strong high-pressure area over the Pacific side of the Arctic, combined with a low-presure area between Greenland and Svalbard. Although this isn't an ideal distribution for general ice transport and compaction, due to their size I expected them to do more than they did (which was above average nevertheless).
Here's an animation of SLP images from the DMI Centre for Ocean and Ice of the past week:
That huge high-pressure system can't be missed. Right now it has moved over the East Siberian Sea, and even though ideally it should have moved the other way, it will probably have a marked effect on the slush puppy below, as it pulls in warm air from Siberia and disperses clouds to make room for that last bit of insolation of the season. As meteorologist Jeff Masters wrote on his excellent blog yesterday:
Arctic sea ice poised to undergo record decline in mid-August
A strong high pressure system with a central pressure of 1035 mb has developed over the Arctic north of Alaska, and will bring clear skies and warm southerly winds to northeast Siberia and the Arctic during the coming week, accelerating Arctic sea ice loss. Widespread areas of northeastern Siberia are expected to see air temperatures 4 - 12°C (7 - 22°F) above average during the coming week, and the clockwise flow of air around the high pressure system centered north of Alaska will pump this warm air into the Arctic.
I agree with Masters that we are currently seeing this high and according to the ECMWF weather forecast maps it will more or less stay put in the coming 5 days:
Towards the fifth day, however, we see the high extending all over the Siberian coast and a low forming over the Canadian Archipelago and Beaufort Sea. This is the exact opposite of the ideal Dipole Anomaly set-up and if it comes about, it will probably halt the above average extent decrease we are going to see in the coming days (as shifting weather patterns are prone to do). But it's a bit too early to tell, as weather forecasts become less trustworthy the further out they are.
The ice on the Pacific side of the Arctic is holding out longer than I expected, with divergence keeping the extent numbers from plummeting. But the coming 3-4 days will be a real test for the slush puppy.
2011 is probably going to get closer to 2007, but again, I believe it has to be within 150K square km (at the very least!) by August 20th if it wants to have a chance at reaching a new record minimum extent. The weather is probably going to make that close to happen this week, but after that the battle between freezing air temperatures and compaction/bottom melt is on.
We are slowly entering the final phase of the melting season, but first it looks like we are having an exciting week ahead of us.
PS I've been a bit extra busy lately and in the process of buying a dilapidated farm, so I can't do too many blog posts between SIE updates. All the interesting stuff is in the comment sections anyhow.:-)
TIPS - Other blog posts and news articles concerning the Arctic and its ice:
Most of you will probably heard about this, but an MIT study says Arctic ice thinning 4x faster than predicted. I don't find it newsworthy enough to turn it into a new blog post, even though I did that for Funder et al and Kay et al papers.