"Our greatest responsibility is to be good ancestors."

-Jonas Salk

Friday, June 20, 2008

Sea Ice Update

Well, as the sun reaches its azimuth in the north, we find ourselves neck and neck with last year in Arctic ice area and thus ahead of last year in seasonal ice area loss.

The first image is from the graphics guys at UNEP, and shows some of their usual sloppiness. The "79-00 average" must be for the seasonal minima, though this is not made clear. However, the data look right and are obviously spectacular. This should be no surprise to those of you who have been following climate news for over a year.

Now much was made of the fact that the area anomaly bounced right back to the trend line in late fall. The pollyanna camp suggested that it was just a glitch. The cassandra camp contested this, pointing out that young ice and old ice aren't exactly the same substance (yes, they're both water, but the older ice is harder and has fewer structural weaknesses) and that young ice is relatively thin. This camp appeared to me on the whole to be the one with more expertise, though we found William in the more pollyannish camp.

Perhaps my opinion of who had the real chops was deflected a bit by the inevitable crowing of the cherry-pickers' union. The further you are from a topic the harder it is to filter out uninformed opinion, and to be honest I have always avoided sea ice: the math is actually very messy. (It's three kinds of continuum blended together: elastic, viscous and plastic depending on where and when!)

So the time to prove the pudding is approaching.

From the NSIDC along with the graph of current data:
June 3, 2008 - Arctic sea ice still on track for extreme melt
Arctic sea ice extent has declined through the month of May as summer approaches. Daily ice extents in May continued to be below the long-term average and approached the low levels seen at this time last year. As discussed in our last posting, the spring ice cover is thin. One sign of thin and fairly weak ice is the formation of several polynyas in the ice pack.
I understand there's some bets outstanding as to whether last year's record minimum will be overturned. This will give us some strong indication of whether the final meltdown of perennial sea ice is imminent or is still decades away as was thought prior to last season.



HumbleBarFly said...

Showtime indeed. Perhaps an "oh shit" moment as well.

S Molnar said...

Well, polynyas in the ice cap are all well and good, but let's see a few of those Pollyannas in the ice cap.