Sea ice continues to get lots of attention. I previously discussed March 2008 results here. June 2008 results should be available soon, but in the mean time, I’ve updated my own graphics showing a tripartite image of global, SH and NH, instead of only showing NH sea ice, as done in other recent comments e.g. Phil here, the UK Independent and Michael Tobis here.
First, I’ve uploaded a script that collates the SIDADS information into coherent time series (see http://www.climateaudit.org/scripts/seaice) and can be a tool for people wishing to carry out their own analyses.
Here is a tripartite plot of global, SH and NH sea ice, expressed here as monthly anomalies (in million sq km). On a global basis, sea ice anomalies in May 2008 continue to be above the long-term average during the 1979-2008 satellite period – the 10th highest on record. SH sea ice is off a bit (in anomaly terms) from record levels earlier in 2008, but remains at near record levels (3rd highest May anomaly). In fairness to last year’s commenters on Arctic sea ice, 2007 sea ice levels really do stick out relative to other values during the satellite period; May 2008 NH sea ice are not as extreme as last year’s (10th lowest.)
Re-examining the schedule of last year’s melt to see when milestones could be expected for this year, I was a little surprised at how late in the season the separation from other year’s took place. As of June last year, the year had been a relatively high melt year, but looking at the monthly data in retrospect, I don’t see how one could have predicted the August and September melts at this time least year. If anti-alarmists happen to read this post, I would urge you to defer any conclusions until the summer is over.
Update: Daily NH sea ice concentration data is available here http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv calculated differently than the monthly data previously shown but highly correlated. The mean of June 2008 daily sea ice in this data set was 0.11 MM sq km greater than the corresponding value in June 2007. I used this to estimate the June 2008 monthly value in SIDADS methodology yielding a SIDADS estimate of 11.64 MM sq km, plotted below.