Only time will tell if 2008 marked the tipping point for the Arctic sea ice, but it may well have been. (Click on the photo to enlarge.)
Last year, at this time, the ice was much thicker and had not yet exhibited large cracks all over the surface (as observed from the satellite photos, which are updated several times per day -- you can find these at: http://www.weatheroffice.gc.ca/satellite/index_e.html. They are the IR at 10.7 µm.).
This latest satellite photo shows that the freeze this winter has not restored the ice to its former state, not by a long shot.
The view (click to enlarge), below, is of the ice off of northern Canada, with a bit of Ellesmere Island in the upper right corner, and Alaska's northern coast in the lower left.
http://www.weatheroffice.gc.ca/data/satellite/hrpt_yrb_ir_100.jpg
These photos don't make the case for the Arctic ice not recovering. Cracks in the ice pack are a normal feature, called leads. You get more and fewer of them depending on the current meteorology.
ReplyDeleteThe rift/fault line along the western edge of the Canadian Archipelago, in particular, is a typical feature. When the winds are onshore, some ice rafts (floes get shoved on top of each other), some ridges, etc. When the winds turn offshore (which looks to be the case here -- looks like a comma cloud system to the NW of the Archipelago) leads open up as the ice floes separate. New ice takes time to grow thick enough to be seen in an AVHRR image like this.
The other feature of ice is that it is not a solid sheet across the arctic. It's made up of floes, varying from, say, 10 meters to 10 kilometers across. If winds are along-shore, ice tends to start flowing in shore-parallel lanes with gaps between them. The gaps (leads) because the ice floes themselves are large. If there were no gaps, then the flow would be much slower as it would be rafting, ridging, and such.
You can get similar effects with things like oatmeal, wet concrete, wet sand, ... in thin layers.
A strong reason to think the Arctic ice pack is not recovering is the fact that we're soon to pass 6 straight years where every day's extent has been below the climatology. Going over 2000 days below climatology is definitely significant.
My current disagreement aside, I've been reading your blog for quite a while now and enjoy it. It's nice to see the more considered science articles and you select a good batch. Even here, where I happen to disagree, you present enough solid material that we can disagree intelligently. Nice.
Well, thank you for that comment.
ReplyDeleteI had meant to post comparison satellite photos from last year, but they are on my other PC, which is out to lunch indefinitely.
Last year, no such cracks were visible. In fact, the ice was so intact that, once fissures began to develop, it was possible to see the streams of water vapor pouring out of them up into the air. In fact, it was such a dramatic sight that I took to checking the satellite images several times per day just to see them. This occurred over a period of perhaps 6 to 8 weeks, at least. Only much later were large cracks visible anywhere near the Canadian archipelago.
If I can ever get the old PC cranked up again, I will post some comparison satellite photos so that you can see what I mean.
(Think in terms of a vast expanse of pure white across the entire Arctic Sea, no cracks or fissures visible. That was last year at this time.)
Thanks for the motivating comments.
ok, so I googled your name, and it seems clear that you should know more about this subject than I, but I will try to get those images up for comparison, but first I have to buy another energy supply and hope for the best as that PC has been trying to give up the ghost for a long time.
ReplyDeleteNo problems. If I'm right about what is going on, then just keep an eye the next few days on the AVHRR images you've been looking at. If the cracks persist in their current orientation even after the winds turn to being on-shore, then I'm wrong about what's happening. If they disappear, or orient along with the winds, then the sort of thing I'm talking about is happening. A single image doesn't resolve this question, regardless of what Feb 13 of some other year shows. But the progression of images -- looking at the ice dynamics -- will show us what is up.
ReplyDeleteI'll also take a look for some of the AIDJEX covers (1970s Arctic sea ice experiment). IIRC, they show similar features. The covers (and journals) are supposed to be online now, but I forget whether it's UW Seattle or the NSIDC which hosts them online.
I have a confession to make. I was so captivated by the wispy grey streaks that began to appear in the satellite images that I became nearly addicted to checking on them every day, several times per day. I stored a great many of the images on my PC. At first, they completely mystified me, then I realized that fissures were forming and the relatively warmer water was coming out as vapor. It was easy to watch in the first few weeks because the skies were so clear over the Arctic at that time. Later, the vapor itself was in such quantity that it began to obscure the details. In any case, I will have to look at a Canadian map in order to describe the other large differences in the ice cover, compared to last year. My knowledge of geographical names from the region is pretty sketchy.
ReplyDeleteYes, individual images cannot tell us much, but I stored more than I can count.
(So, right now, you'll just have to take my word for it... or not...)
NOT
ReplyDeleteDear Penguindreams,
ReplyDeleteMy PC's power supply is out to lunch permanently, so it will be a while (a few weeks, I think) before I can get it up and running.
But the difference in the ice between last year and this year is so dramatic that I will do this.
And, I can't be the only one who has seen this. What about the Canadian MET people who run that site? They should have a vast archive of past images.
Hmmm, I could try to get in touch with them, but it would help if I knew exactly which day I wanted. However, at this time last year there was almost no cloud cover interferring.
Well, I will see about contacting them.