Arctic Sea Ice

SEARCH 2014 Sea Ice Outlook: August report

The last Sea Ice Outlook of this year has been published. The SIO is now organized by the Sea Ice Prediction Network (as part of the Arctic research program 'Study of Environmental Arctic Change', or SEARCH), and is a compilation of projections for the September 2014 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs (public outlooks).

Here's the summary for the August report:

Thank you to the groups that contributed to the August 2014 Outlook. We received 23 pan-Arctic contributions. Of the 23 contributions, some are unchanged from July. The median Outlook value for September extent is 5.0 million square kilometers with a quartile range from 4.58 to 5.22 million square kilometers. The overall range is between 4.0 and 5.6 million square kilometers. The median value for August is increased from the June and July values of 4.7 and 4.8 million square kilometers, respectively. This increase reflects the relatively slower decline in ice extent through August than what had been projected earlier. The overall range has narrowed since July, suggesting that the projections are tending to converge, as one would expect with a shorter forecast period. There were four regional Outlooks submitted with a fairly large range in both spatial extent and ice-free dates. There have not been any significant extreme weather events this summer as was seen during the record low years of 2007 and 2012. The more quiet conditions have likely played a role in the evolution of the sea ice extent this summer. While the extent is far from a record low, all contributions will put 2014 as one of the ten lowest September extents in the 36-year satellite record.

Read the entire report here.

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

SEARCH 2014 Sea Ice Outlook: July report

The second Sea Ice Outlook of this year has been published. The SIO is now organized by the Sea Ice Prediction Network (as part of the Arctic research program 'Study of Environmental Arctic Change', or SEARCH), and is a compilation of projections for the September 2014 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs (public outlooks).

Here's the summary for the July report:

The median Outlook value for September 2014 sea ice extent is 4.8 million square kilometers with quartiles of 4.4 and 5.0 million square kilometers. Thus, the median value is slightly higher than the June value (4.7) and the distribution of Outlooks is slightly reduced relative to June. The overall range is now from 3.2 to 5.9 million square kilometers. These values compare to observed values of 4.3 million square kilometers in 2007, 4.6 million square kilometers in 2011, 3.6 million square kilometers in 2012, and 5.4 million square kilometers in 2013.

Sea ice declined at a pace more rapid than normal during June, particularly late in the month when extent decreased by over 100,000 square kilometers per day. The decline has since slowed somewhat.

The Sea Ice Outlook is a venue for discussion and networking and provides a transparent exercise in both scientific sea ice predictions as well as estimates from the public. The post-season activities will provide more of a scientific analysis of the methodologies, relative performance, etc.

This month's full report includes the comments on modeling outlooks and on regional predictions, a summary of current conditions, key statements from each Outlook, and links to view or download the full outlook contributions.

And here's the graph to go with the SIO, showing all the predictions (here's last month's version):

So, the median went up from 4.7 to 4.8 million km2, which is logical given the flip in weather conditions that put a damper on the fast declines in the two-three preceding weeks (more on that in the next ASI update this weekend). The highest prediction by Wang using the CFSv2 model went down from 6.3 to 5.9 million km2, though.

No WUWT poll was submitted for this July SIO, so we can't average it with the ASIF poll, which resulted in a predicted NSIDC September SIE average of 4.17 million km2 (up from 3.95 million km2 in June). You can check my spreadsheet with the poll results on Google Drive, to see if I've made a mistake. There will be a new and final poll on the ASIF, come August 1st. Be sure to vote, everyone! Even though there won't be a new record this year, it's still very interesting to see whether 2014 ends up near/in the top 3, or stick with 2013.

Here's some more context, ie the September minimums for the last 9 years (in millions km2, found here):

    2005: 5.57
    2006: 5.92
    2007: 4.30
    2008: 4.73
    2009: 5.39
    2010: 4.93
    2011: 4.63
    2012: 3.63
    2013: 5.35

SEARCH 2014 Sea Ice Outlook: June report

The first Sea Ice Outlook of this year has been published. The SIO is now organized by the Sea Ice Prediction Network (as part of the Arctic research program 'Study of Environmental Arctic Change', or SEARCH), and is a compilation of projections for the September 2014 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs (public outlooks).

Here's the summary for the June report:

The median Outlook value for September 2014 sea ice extent is 4.7 million square kilometers with quartiles of 4.2 and 5.1 million square kilometers (See Figure 1 in the full report, below). Contributions are based on a range of methods: statistical, numerical models, estimates based on trends, and subjective information. We have a large distribution of Outlook contributions, which is not surprising given the different observed values in 2012 and 2013. The overall range is also large at 3.2 to 6.3 million square kilometers. The median outlook value is up from 4.1 million square kilometers in 2013. These values compare to observed values of 4.3 million square kilometers in 2007, 4.6 million square kilometers in 2011, 3.6 million square kilometers in 2012 and 5.4 million square kilometers in 2013. Only three outlooks this year are above the 2013 observed September extent.

As the season progresses, it will be interesting to follow the relative influences of weather (i.e., warm Arctic winter in 2013/2014 and the wind and weather through the summer) and initial conditions of the sea ice, all in the context of the long-term downward trend of sea ice extent.

Read the entire report here.

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

The September minimums for the last 9 years (in millions km2, found here):

More on melt ponds

After you've read the blog post below, make sure to check out this web page by one of the co-authors of the Nature paper, and also this page with lots of other Arctic sea ice goodies.

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A really good paper has been published online a couple of days ago on Nature, called September Arctic sea-ice minimum predicted by spring melt-pond fraction. It's really good because it's interesting, short, and it confirms what I've been suspecting for a while now. And when a paper confirms what one is suspecting, it must be really good, right?

All joking aside, the paper by Schröder et al. presents evidence that melt ponds play a very important role at the start of the melting season, to the point that it can heavily influence the September minimum. The last two melting seasons actually proved to be a great lesson in this respect. 2012 had a really good* start to the melting season, so good that when bad weather showed up, it didn't really slow down sea ice loss, the trend lines just kept dropping (low sea ice volume also played a role, of course). The reverse was true in 2013: cold and cloudy weather during the first half of the melting season caused a lagged response during the short periods when the Sun and higher temps finally got to the ice.

What Schröder et al. did, was develop a melt pond model and incorporate it into the larger Los Alamos sea-ice modelcalled CICE. Here's what they came up with:

Forecast me not

Tomorrow, April 1st, I'll be doing a short presentation on the Sea Ice Prediction Workshop that will be webcast by UCAR. I'll be talking 10-15 minutes about the ASIB, ASIG and ASIF, and about increasing public interest in Arctic sea ice. You can view the webcast here.

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It was always clear how difficult it is to forecast the Arctic sea ice melting season, but this realization reached an even deeper level in the last two years (more about that a couple of paragraphs below). A lot of scientists are working hard to improve the science of predicting the yearly sea ice minimum, and some of them have now evaluated these forecasting efforts, using data from the interagency "system-scale, cross-disciplinary, long-term arctic research program" SEARCH (Study of Environmental Arctic Change) Sea Ice Outlook, which was set up after the drastic sea ice decline of 2007. These monthly SIO predictions have been extensively covered on the ASIB the past 4 melting seasons.

The study by Stroeve et al. (including ASIB guest blogger Larry Hamilton) is called Predicting September Sea Ice Ensemble Skill of the Search Sea Ice Outlook 2008–2013, has just been published in Geophysical Research Letters, and its abstract reads as follows:

Since 2008, the SEARCH Sea Ice Outlook has solicited predictions of September sea ice extent from the Arctic research community. Individuals and teams employ a variety of modeling, statistical and heuristic approaches to make these predictions. Viewed as monthly ensembles each with one or two dozen individual predictions, they display a bimodal pattern of success. In years when observed ice extent is near its trend, the median predictions tend to be accurate. In years when the observed extent is anomalous, the median and most individual predictions are less accurate. Statistical analysis suggests that year-to-year variability, rather than methods, dominate the variation in ensemble prediction success. Furthermore, ensemble predictions do not improve as the season evolves. We consider the role of initial ice, atmosphere and ocean conditions, and summer storms and weather in contributing to the challenge of sea ice prediction.

Crowd-Source Prediction of September Sea Ice Extent (July report & call for August predictions)

In mid-June through early July, participants on the Arctic Sea Ice (ASI) blog posted 82 individual predictions for the mean NSIDC September Arctic sea ice extent. The median value of these 82 predictions was 3.2 million km², with an interquartile range (approximately the middle 50% of predictions) from 2.7 to 3.9 million km².

Figure 1

Medians and quartiles are employed as basic summaries here because they offer high resistance to outliers, are easy for anyone to replicate, and map into more detailed analysis using graphics or quantile regression. Individual predictions ranged from 0 to 5.6 million km². A stem-and-leaf display compactly shows the distribution:

SEARCH 2013 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 2013 Arctic sea ice extent, based on NSIDC monthly extent values. These projections are submitted by professionals as well as amateurs (public outlooks).

Here's the summary for the June report:

With 23 pan-arctic Outlook contributions, an increase over the last two years (thank you!), the June Sea Ice Outlook projects a September 2013 arctic sea extent (defined as the monthly average for September) median value of 4.1 million square kilometers, with quartiles of 3.8 and 4.4 million square kilometers (Figure 1).

The consensus is for an increasing downward trend of September sea ice extent. We interpret the split of 2013 Outlooks above and below the 4.1 median to different interpretations of the guiding physics: those who considered that observed sea ice extent in 2012 being well below the 4.1 level indicates a shift in arctic conditions, especially with regard to reduced sea ice thickness and increased sea ice mobility; and those with estimates above 4.1 who support a return to the longer-term downward trend line (1979-2007). It is always important to note for context that all 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):

Crowd-Source Prediction of Mean September Sea Ice Extent (July update)

Each June, July and August, the SEARCH Sea Ice Outlook (SIO) collects predictions for the mean extent of Arctic sea ice in September. These predictions come mainly from scientists but also some other people, drawing on a variety of modeling, statistical or subjective methods that each contributor describes in written documentation. The first round of SIO predictions, submitted by June 7, have just been published online. Twenty-three contributors suggest values ranging from 3.4 to 6 million km², with a median of 4.1.

In a post last month on this blog, I invited readers to submit their own predictions. By my count a total of 116 predictions were posted by the June 7 deadline, along with some interesting discussion. My original post had an ambiguous title, leading some people to offer predictions for the one-day minimum instead of the September mean, so I view this first round as an experiment. But from here on we’ll look at how that experiment came out.

 Figure 1

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.