2013 Sea Ice Estimates

Our June guesses for 2013 are 3.9, 4.1, and 4.4 million km^2 for September monthly average sea ice extent as computed by NSIDC.  See the ARCUS SEARCH Outlook for the full current collection of estimates.

Again, I'll put our estimates in context of some other estimation methods. 

• Climatology 1979-2000: 7.03 million km^2
• Climatology 1979-2008: 6.67 million km^2
• Linear Trend Climatology 1979-2008: 5.15 million km^2
•  
• Wang, Wu, Grumbine model: 4.4 million km^2
• Wu, Grumbine, Wang model: 4.1 million km^2
• Grumbine, Wu, Wang statistical ensemble: 3.9 million km^2

All three of our estimates are well below what they were last year -- 4.9, 4.8, and 4.4 million km^2, respectively.  For the two model-based estimates, this is because the model has continued to thin its ice cover, and that ice cover is less extensive.  Then the model (which is coupled air-sea-ice) is not seeing any reason for the ice to be getting markedly thicker or more extensive.

The statistical ensemble reflects two items.  One is, last year being a new record, well below the estimate (by 0.8 million km^2), pulled down the best curves that can be fit through the data.  The second is, the curve itself shows a zone of steep decline.  This is where the feedback of more open water -> warmer ocean -> thinner ice -> easier to melt ice -> more open water in summer is starting to take off rapidly.  (If the basis for my using this curve is reasonably correct, that is.)

The linear 'climatology' estimate last year was 5.23 million km^2, versus the observed 3.61.  Too high that year, and every year 2007-2012, and very likely many more to come.  Merely points to a straight line not being a good representation of how the ice pack is changing, which is no surprise.  But it is also a reminder that talk of sea ice 'recovery', which will no doubt occur in some corners when (if) 2013's extent is greater than 2012's, is nonsense. 

2012 Sea Ice Prediction Evaluations

Before launching in to my estimates for this year, I have to evaluate last year's estimates.  Not much point in making estimates if you don't re-examine how well the previous ones were.

Last year's observed (NSIDC) September monthly average sea ice extent was 3.6 million km^2.  That blew away the old record set in 2007.

Our June 2012 Estimates were:
4.9 Wang, Grumbine, Wu -- statistical correction of CFS
4.8 Wu, Grumbine, Wang -- semi-physical correction of CFS
4.4 Grumbine, Wu, Wang -- Purely statistical from prior Septembers

July:
4.9 Wang, Grumbine, Wu -- statistical correction of CFS
4.7 Wu, Grumbine, Wang -- semi-physical correction of CFS

August:
3.9 Wang, Grumbine, Wu -- statistical correction of CFS

No updates in August for the semi-physical CFS correction as it hadn't looked like it was coming out any different than the prior months.

The Wang et al. was the best of all August estimates, and was still too conservative by 300,000 km^2 (the approximate land area of Poland, the Philippines, Norway, or Ecuador).  The observed mean extent, of 3.6 million km^2 was about 20% larger than India.  The 1979-2000 average was 7.0 million km^2 -- almost double what we just saw, and about the 10% smaller than Australia.

Question place

Have at it -- questions welcome.  Answers probably of higher quality (from me, at least) if they're about ice, sea surface temperature, and related parts of the climate, or about running. 

Also suggestions welcome.

Hiatus

Last week was hiatus because I was working on things that didn't quite make it to completion.  This includes evaluating last year's sea ice estimates (Alastair won both his bets with me so is now even), and writing up this year's estimates (all our estimates are lower than last year this time, but not as low as last year's observations).

This week, it is that I away from home and had a hard computer failure.  I don' like long typing on a touch screen, which is what I'm doing at the moment, so twitter is about it this week.  @rgrumbine.

See you next Monday, when I'll hang out the 'question place' shingle.

Science's Spock Problem

XKCD captured perfectly where scientists start from in terms of relating to others about their subject:

What we do, the part of the universe we study, is wonderful, fascinating, and we want to run around sharing our wonderful discoveries with everybody.  Including when it's dog vomit slime molds.  See also my niece's write up from jr. high about knight anoles.

And that's what makes the Spock problem such a problem.  What I mean by this is that there is heavy cultural (in the US at least) expectation that scientists _are_, or at least _should_ be, like Mr. Spock -- emotionless, heartless, 'rational', and fundamentally not human.  Humans, and scientists are human, do generally respond to society's expectations.  One common response being to present a public appearance of conforming to those societal expectations.  In private, it can be a different matter.  But, per yesterday's comment, scientists do tend to play in to this expectation in public and it doesn't, I think, work well in the larger society.  So public gets the wildly wrong idea in that case that scientists don't criticize each other, among other wildly wrong ideas.

Read more »