Arctic Sea Ice

August SEARCH Contribution Update

I usually give you an advance view of my outlook contributions. There is little point doing that now it is available from SEARCH site, but by way of explanation the great Arctic Summer storm was in progress by the time it was ready to submit so Neven blog seemed very busy and the projection was out of date before it was submitted due to that summer storm. So there seemed little point adding out of date projections to an already very busy blog.

SEARCH 2012 Sea Ice Outlook: August report

The third and last Sea Ice Outlook of this year has been released. The SIO is organized by the interagency "system-scale, cross-disciplinary, long-term arctic research program" SEARCH (Study of Environmental Arctic Change), and is a compilation of projections for the September 2011 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs, such as our own Chris Randles and Larry Hamilton.

Here's the summary for the August report:

With 23 (thank you!) responses for the Pan-Arctic Outlook (plus 5 regional Outlook contributions), the August Sea Ice Outlook projects a September 2012 arctic sea extent median value of 4.3 million square kilometers, with a range of 3.9–4.9 (Figure 1). The quartiles for August are 4.1 and 4.6 million square kilometers, a narrow range given that the uncertainty of individual estimates is on the order of 0.5 million square kilometers. The consensus is for continued low values of September 2012 sea ice extent. The August Outlook median is lower by 0.3 million square kilometers than the July estimate, consistent with low summer 2012 observed values. According to the National Snow and Ice Data Center (NSIDC), the arctic sea ice extent for July 2012 was the second lowest in the satellite record behind 2011; the ice extent recorded for August 1st of 6.5 million square kilometers is the lowest in the satellite record. Twelve of the contributions give a value equal to or lower than the 2007 record minimum (monthly average) extent of 4.3 million square kilometers.

And here's the figure showing all the projections (click for a larger version):

The median value went down from July's 4.6 million square km to 4.3 million square km for the September average as calculated by the NSIDC. This corresponds quite closely with the 4.24 million square km that resulted from the July poll that was held here on the ASI blog (you can vote one last time, using the widget in the right hand bar, until August 20th).

These are the September monthly average minimums in the 2005-2011 period:

• 2005: 5.57 million square km
• 2006: 5.92 million square km
• 2007: 4.30 million square km
• 2008: 4.73 million square km
• 2009: 5.39 million square km
• 2010: 4.93 million square km
• 2011: 4.61 million square km

If you want to compare this outlook with those of previous years, there's an archive on the SEARCH home page (in the left hand bar). Here's an overview of blog posts on this subject in 2010 and 2011.

SEARCH 2012 Sea Ice Outlook: July report

The second Sea Ice Outlook of this year has been released. The SIO is organized by the interagency "system-scale, cross-disciplinary, long-term arctic research program" SEARCH (Study of Environmental Arctic Change), and is a compilation of projections for the September 2011 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs, such as our own Chris Randles and Larry Hamilton.

Here's the summary for the July report:

With 21 responses for the Pan-Arctic Outlook (plus 5 regional Outlook contributions), the July Sea Ice Outlook projects a September 2012 arctic sea extent median value of 4.6 million square kilometers (Figure 1) [The median value for the 2011 July SIO was also 4.6 million square km, N.]. The consensus is for continued low values of September sea ice extent. Individual responses are based on a range of methods: statistical, numerical models, comparison with previous rates of sea ice loss, composites of several approaches, estimates based on various non-sea ice datasets and trends, and subjective information. Again, it is important to note for context that the estimates are well below the 1979–2007 September mean of 6.7 million square kilometers. The quartiles for July are 4.2 and 4.7 million square kilometers, a rather narrow range given that the uncertainty of individual estimates are on the order of 0.5 million square kilometers. This is also a narrower range than last year, which was 4.0 to 5.5. The July Outlook is generally similar to the June Outlook; the July median is higher by 0.2 million square kilometers than the June estimate, but the quartiles are similar.

And here's the figure showing all the projections (click for a larger version):

These are the September monthly average minimums in the 2005-2011 period:

• 2005: 5.57 million square km
• 2006: 5.92 million square km
• 2007: 4.30 million square km
• 2008: 4.73 million square km
• 2009: 5.39 million square km
• 2010: 4.93 million square km
• 2011: 4.61 million square km

If you want to compare this outlook with those of previous years, there's an archive on the SEARCH home page (in the left hand bar). Here's an overview of blog posts on this subject in 2010 and 2011.

July SEARCH Contribution

My July contribution is as follows. Please feel free to comment.

1.    Extent Projection 4.0 +/- 95% confidence interval of 0.9 M Km^2 based on past forecast performance of this technique.

SEARCH 2012 Sea Ice Outlook: June report

There it is, the first Sea Ice Outlook of this year. The SIO is organized by the interagency "system-scale, cross-disciplinary, long-term arctic research program" SEARCH (Study of Environmental Arctic Change), and is a compilation of projections for the September 2011 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs, such as our own Chris Randles and Larry Hamilton.

Here's the summary for the June report:

With 19 responses for the Pan-Arctic Outlook (plus 6 regional Outlook contributions), the June Sea Ice Outlook projects a September 2012 arctic sea extent median value of 4.4 million square kilometers, with quartiles of 4.3 and 4.7 million square kilometers (Figure 1) [The median value for the 2011 June SIO was 4.7 million square km, N.]. This compares to observed September values of 4.6 in 2011, 4.9 in 2010, and 5.4 in 2009. Both the 2012 quartile values and the range (4.1 to 4.9) are quite narrow. The 2012 June Outlook differs from all previous Outlooks in that there are no projections of extent greater than 5.0. It is always important to note for context that all 2012 estimates are well below the 1979–2007 September mean of 6.7 million square kilometers.

And here's the figure showing all the projections (click for a larger version):

These are the September monthly average minimums in the 2005-2011 period:

SEARCH Outlook Contribution May 2012

My SEARCH contribution follows. However, I want to say this is the best statistical scheme I have found and doesn't necessarily mean I believe it. If I was submitting a huristic estimate then I would be saying:

I find myself concerned at the rapid drop in area and the appearance of the ice. High area in March April and May in southerly locations should have reflected more solar radiation and kept things cool. Despite this Chukchi isn't far behind normal. The volume is about the same as last year but spread more thinly into southerly locations. The time for that to slow down retreat of areas like Chukchi has almost past and it seems to me as if the thinner ice at more northerly locations will now cause faster retreat so that areas like Chukchi can catch up if not overtake. On the Atlantic side, so far the weather has prevented fast retreat in these weak ice area. That is unlikely to continue indefinitely and despite the weather the Barents and Kara are still looking very weak compared to past years. I think there has been high outflow through Fram strait, and high Atlantic water heat content inflow recently and low snow cover in April and May around the arctic basin.

September 2011 sea ice volume, looking back and ahead

Last spring I proposed Gompertz curves as simple models for thinking about past and future trends in Arctic sea ice extent, area and volume. Extent and area predictions made using these models in April came close to the observed September means:

NSIDC extent — predicted 4.4, observed 4.6

UB extent — predicted 4.6, observed 4.6

NSIDC area — predicted 3.1, observed 3.2

But the April volume prediction, based on what seemed at the time to be a pessimistic model, turns out to have been too high:

PIOMAS volume — predicted 5.2, observed 4.2

As estimated by researchers at the Polar Science Center of the University of Washington, using the PIOMAS model (website, data), the mean volume for September 2011 was only 4.2 thousand km³. Figure 8 shows this result together with a new Gompertz curve, which points toward a September 2012 mean of 4.0 thousand km³. Whereas the earlier model showed volume reaching very low levels (below 2 thousand km³) around 2016, this new version crosses that line one year sooner.

 
Figure 8

September 2011 sea ice extent, looking back

Daily changes in the graphs, maps and numbers assessing sea ice are entertaining to follow. The day-to-day discrepancies between output from different research teams get close scrutiny by those of us on the outside, trying to learn more about what’s happening to the ice. Seen from the step-back view of monthly averages, however, daily disagreements blur into substantial agreement. Figure 4 illustrates by plotting time series of September means for five main indices produced by the National Snow and Ice Data Center (NSIDC: website, data), the University of Bremen’s Institute of Environmental Physics (Uni Bremen: website, technical paper), IARC-JAXA Information Systems (IJIS: website, data) and the Polar Research Group at the University of Illinois (Cryosphere Today: website, data). So far as I know, Figure 4 is the first graphic to show these five September series together. Disagreements among the indexes appear minor; all five vary together around declining area or extent trends that steepen over the period of observation.

 
Figure 4

September 2011 sea ice extent, looking ahead

The mean extent of Arctic sea ice for September 2011, calculated from the University of Bremen time series (website; technical paper), was 4.6 million km². A Gompertz curve that I estimated last April based on Uni Bremen data for 1972 through 2010 gave a predicted September 2011 mean of ... 4.6 million km². Encouraged by this lucky guess (and that’s what it was!), I here offer an even earlier and more naive prediction for the UB September 2012 mean ... 4.3 million km², with a confidence interval of ±.8 (Figure 1).

Figure 1

IJIS SIE: 5 million km2 mark passed

Seke Rob has been treating us with fantastic graphs for many weeks now, and it's high time I picked one out for a highlight. IJIS sea ice extent broke through the 5 million km² barrier yesterday. This graph shows how many days it has taken to drop from one million to the next from the date of maximum extent onwards (click on the link above for a larger version):

Thanks, Seke Rob!