During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily IJIS sea ice extent (SIE) and Cryosphere Today sea ice area (SIA) numbers, which I compare to data from the 2005-2011 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything that can be of particular interest.
Check out the Arctic Sea Ice Graphs website for
daily updated graphs, maps and live webcam images.
August 25th 2012
I apologize for having provided so little analysis lately, but things are moving so fast that analysis can't keep up. Now I know what an IPCC regional model for the Arctic must feel like. ;-)
Basically, I'm at a loss for words, and not just because my jaw has dropped and won't go back up as long as I'm looking at the graphs. I'm also at a loss - and I have already said it a couple of times this year - because I just don't know what to expect any longer. I had a very steep learning curve in the past two years. We all did. But it feels as if everything I've learned has become obsolete. As if you've learned to play the guitar a bit in two years' time, and then all of a sudden have to play a xylophone. Will trend lines go even lower, or will the remaining ice pack with its edges so close to the North Pole start to freeze up?
Basically I have nothing to offer right now except short posts when yet another of those record dominoes has fallen. Hopefully I can come up with some useful post-melting season analysis when I return from a two-week holiday.
I'm at a loss at this loss. The 2007 record that stunned everyone, gets shattered without 2007 weather conditions. The ice is thin. PIOMAS was/is right.
Sea ice extent (SIE)
WindSat or no WindSat, the 2012 trendline on the IJIS SIE graph has dropped like a rock:
I had to adjust the Y-axis on this graph already once (compared to the one in the last ASI update), and it looks like I'll have to adjust it again. I already announced the new IJIS SIE record minimum yesterday, although it was based on the preliminary number. But after the revision the record is still standing and IJIS still hasn't stopped producing century breaks.
The current difference between 2012 and other years (without the unrealistic last data point that gets revised upwards) is as follows:
- 2005: -1,644K (-49,701)
- 2006: -1,834K (-45,827)
- 2007: -666K (-62,487)
- 2008: -1,218K (-74,030)
- 2009: -1,463K (-53,477)
- 2010: -1,343K (-57,083)
- 2011: -876K (-61,478)
Between brackets is the average daily SIE decrease for the first 24 days of August. 2012's average daily SIE decrease for those first 24 days is -95,417 km2 per day. Woops, there goes my jaw again.
Sea ice area (SIA)
Cryosphere Today sea ice area data has gone so low, it frightens me bit.
Luckily the steepness of the decline has started to wear off a bit, as the interior of the ice pack and the last melt ponds slowly start to freeze or get snowed over. But it could go lower still, as there is still a huge amount of loose ice floes out there.
The anomaly is so low, that I don't see how it will not turn into another record domino when freeze-up starts again, but much slower than during the baseline period (1979-2008):
The current difference between 2012 and the other years is as follows:
- 2005: -1,415K (-65,335)
- 2006: -1,532K (-30,894)
- 2007: -618K (-55,315)
- 2008: -814K (-73,417)
- 2009: -1,205K (-50,357)
- 2010: -941K (-41,443)
- 2011: -566K (-51,660)
Between brackets is the average daily area decrease for the first 23 days of August. 2012's average daily area decrease for those 23 days is -84,458 square km per day. That's just insane for this time of the year.
Cryosphere Today area per IJIS extent (CAPIE)
The CAPIE record has already been broken this year, right before the Arctic summer storm came along. It was in a sense the first record domino,together with the earliest date for CT SIA to drop below the 2 million negative anomaly mark.
CAPIE tells us something about the compactness of the ice pack. In this phase of the melting season, a low percentage basically tells us that the ice pack is spread out a lot. When the CAPIE trend line shoots up, compaction is going on. See this blog post for everything you want to know about this measurement we devised ourselves at the ASI blog.
It's been a while, but the 2012 trend line is no longer lowest. Extent has been dropping fast in the past week compared to area, which is a sign that the ice pack is compacting, and loose individual floes disappear.
Regional SIE and SIA
Regional graph of the week:
I bet you were wondering which graph would be the regional graph of the week this time, right? Well, it's the graph that was featured in Record dominoes 5. Like I wrote over there:
This is just a regional sea ice area graph put out by Cryosphere Today, but it happens to be the most important regional graph out there. This is the place where the last ice is expected to be if and when the Arctic is approaching an ice-free state.
It will either go below 2 million square km, which is insane, or it won't and stay crazy like it is right now. What else is there to say?
Sea Level Pressure (SLP)
Let's have a look at the animation of SLP images from the Danish Meteorological Institute to see what has happened with regards to atmospheric patterns in the past two weeks:
First we see another cyclone (blue) coming in via the Bering Strait, but fizzling out. More interesting things happen in the centre of the Arctic where a couple of days ago something that looks like a Dipole Anomaly set up for a short while. Although the ice pack is so small, but at the same time dispersed at the edges right now, I'm not sure what the effect of this DA is or has been, but usually it makes for compaction and we've seen compaction happening on the CAPIE chart. Towards the end of the animation we see another cyclone glide in via Bering Strait, but fizzling out again.
The ECMWF weather forecast for the coming 6 days:
The Dipole Anomaly is definitely finished. In fact, we're seeing a reverse DA with a high over Siberia and a low over the American side of the Arctic. Usually this spells 'slowdown' in neon letters, but I'm not sure what to think any longer. Besides, there's yet another cyclone forming near the Kamchatka Peninsula, moving towards Bering Strait. Maybe it'll fizzle out again, maybe not. I can't remember seeing this pattern in 2011 or 2010, but maybe I was not paying enough attention.
Air temperatures are still relatively high over the Canadian Archipelago and along the Canadian and Alaskan coast, just a bit warmer than normal along the Siberian coast:
This will change when the Arctic seas start releasing their heat to the atmosphere, which usually causes high peaks on the DMI temperature graph for the area above 80N. This can also sometimes be a sign that the freezing season is on its way:
Sea surface temperature anomalies have finally started to go down a bit (compared to two weeks ago), but a huge area is covered with warmer waters than usual. This also has to do with the fact that normally there's ice there, so there's bound to be an anomalously warm temperature when there's water instead of ice:
So when can we expect the rapid drops to level off and the melting season to start working towards the minimum? To be honest with you, I don't have the faintest clue right now. Not to brag or anything, but at the end of the 2010 and 2011 melting seasons I managed to call the minimum at the right time, just slightly before others dared to (calling the maximum was an entirely different story of which I don't want to be reminded). I learned how to interpret weather maps and forecasts enought to be able to say when the melt wouldstop and the freeze begin. But this year is different. The weather maps still offer clues, but not as many as in 2010 and 2011.
This is the melting season when we learned for sure that the ice is thin, not just because CryoSat-2 is largely confirming the modeled PIOMAS sea ice volume data, but because extent and area kept decreasing in July when the weather said it shouldn't. And yes, that cyclone was big, but it could never have done that much damage if large parts of the ice pack weren't on the tip of melting out anyway. The fact that trend lines have continued to plummet until two weeks after the storm ended, proves it.
I really don't know what to expect next, but what I do know is that all the records on daily graphs have been broken in the past week. Regardless of how this melting season ends, we know the ice is getting thinner and thinner, and so it's time for the whole world to look ahead at what an ice-free Arctic could imply. Not for the polar bears or the ice itself, but for modern civilization, for us, humans. Together with Kevin McKinney I have written a piece about this subject that will appear here tomorrow, as well as a shorter version of it on some other blogs.
In the meantime I'll be going on a much-needed two week holiday (with a very slow Internet access, if it works). It's pure coincidence that all the records have been broken right before I leave, as we had planned to go away in this period for a while already. I'll try and read all the comments (take it easy, boys and girls!) and perhaps even post a thing or two. But you know, let the media chew on this one, while we await the PIOMAS September update, keep an eye on a couple of the lesser record dominoes (like IMS, CT SIA anomaly, global sea ice area minimum and anomaly), and the big prize: NSIDC September average.
See you in two weeks!