A few days ago I used a combination of Arctic sea ice volume data from the University of Washington’s PIOMAS model and NSIDC sea ice extent numbers to project that the Arctic Ocean would be effectively ice-free in late summer within ten years. The key to that exercise was the rate at which the volume of sea ice has been declining — 350 km3 per year over the last 30 years for the full dataset, 410 km3 per year over the last 20, and 740 km3 over the last decade at summer minimum. The rate of volume decline has obviously been increasing. Using those numbers to project ice extent in the future is one thing, but they also tell us something interesting about the overall Arctic heat budget — and we can use that to make a rough guess about when the Arctic will become ice-free year round. The answer is surprising…
Earlier this month the US National Snow & Ice Data Center issued its analysis of this year’s Arctic sea ice minimum — at 4.60 million km2 on September 19, the third lowest extent in the satellite record. However extent (defined here) doesn’t tell you everything about the state of the ice — according to the University of Washington’s PIOMAS ice model 2010 managed to set a new record low for sea ice volume.
In terms of the future of the Arctic sea ice, the volume of ice remaining at minimum is a crucial metric because it represents the size of the heat budget buffer between an ocean with a perennial floating ice cap and one that’s seasonally ice-free. For the Arctic to be ice free in summer, that buffer has to disappear, or become a lot smaller. I’ve been writing about sea ice volume for some time, and considered the overall Arctic heat budget in this post a couple of years ago, so news of the new low volume prompted me to think about what it might mean for the extent metric over the next few years. To do that, I downloaded the NSIDC’s September monthly average extent for the last 21 years, and plotted that against the PIOMAS model’s September average monthly volume (kindly supplied by Jinlun Zhang). Here’s what the data looks like when you plot it on the same chart.
The red line at the bottom, labelled “thickness”, is what you get when you divide volume by extent, and that too has been in decline, reflecting the fact that the loss of volume has been happening faster than the reductions in extent.
The first set of ARCUS/SEARCH projections for the September Arctic sea ice minimum have been released, and amid all the mundane statistical, heuristical, and modelistical musing there’s a remarkable effort — and I really do mean remarkable — by one Charles Wilson. Here’s the graphic showing all of the submitted forecasts. See if you can spot Mr Wilson’s offering:
Yes, that’s him on the left. He appears to have no affiliation to any academic institution, but he is not afraid to make a very definite projection. Download the full set of forecasts [pdf], and take a look. He expects a massive melt, leaving the Arctic Ocean more or less ice-free by September. That’s pretty scary, but here’s what he thinks this may bring for the northern hemisphere. Ocean current disruptions will bring 300mph winds to the northern hemisphere:
= Destruction of nearly ALL aboveground structures North of 10 Degrees Latitude = 99% Deaths in USA, Europe, etc. within 2 years. … In the Worst Case:
Immediate Action can create Clouds with: Airplane contrails, seawater mists, or high- altitude sulfur (e.g. heightening Smokestacks at Norilsk).
But it needs to be done in the next few Weeks – – – months before we can be sure an Early Melt WILL happen.
In a comment at ÂµWatts he expands his point a little:
If the Great Melt Off happens = Warm Currents turn around = 300 mph Winds come February or so..
Currently I give it 15%
â€¦ times 6 Billion dead.
Now that’s what I call alarmist.
Eli Rabett, that ever-curious but lovable lagomorph, has noticed the appearance of an apparent annual cycle in the Arctic sea ice area anomaly chart at the excellent Cryosphere Today. I mentioned the same thing in a post on Arctic sea ice back in April, and hinted that I might look at it “another day”. Well, that day has come, not least because the ice “experts” at ÂµWatts have been suggesting it might be a satellite problem (it isn’t).
The usual suspects have been making much of the fact that over the last few weeks Arctic sea ice extent (NSIDC daily graph here) has been bumping around the 30 year average for this time of year. John Cook at Skeptical Science posted on the subject last weekend, making the important point that what matters most is not extent or area, but the total volume of ice that’s present — and that’s showing no signs of “recovery”. John’s post is well worth reading, but it set me off on a very interesting trawl through the references he provided — and drew my attention to a most useful graph of ice volume and trend. It also pointed me to research that suggests the Arctic could be effectively ice-free in summer within ten years — possibly as soon as 2013.