Staying firmly on the topic of IJIS/ADS Vishop ...
About 5 or 6 weeks ago (page 47 on this thread) I made some observations about the annual average values for Arctic SIE as evinced by the data available on the ADS site.
Having returned from being on tour with Bruce Springsteen (
well, OK, having managed to get tickets for his gigs in Glasgow and London) here is a little update incorporating the data up to and including June 30...
1) Annual average extents for the following decades...
(NB All extent values in millions of sq kms, unless otherwise stated.)
1980's 11.957
1990's 11.440
2000's 10.773
For the period 2010 - 2015, the equivalent figure is 10.199 (That's nearly 15% down on the 1980's average.)
2) Actual annual average extents from 2003 onwards.
2003 10.988
2004 10.821
2005 10.489 9th
2006 10.349 7th
2007 10.079 3rd
2008 10.585 11th
2009 10.543 10th
2010 10.324 5th=
2011 10.046 2nd
2012 9.971 lowest
2013 10.418 8th
2014 10.324 5th=
2015 10.111 4th
(NB There were 24 days with missing data. Place-holder values for these were calculated using simple linear interpolation from the before/after values.)
(NBB Out of the 6 most recent years , only 2013 has failed to make the lowest 6 annual averages. The "interloper" was, of course, 2007.)
3) It is hopefully clear that, in any given year, the average from 1st Jan - 31st Dec can easily fail to adequately describe the value reached at the local minima. Concentrating just on the 4 lowest years, as outlined above, their year-end averages were ...
2015 10.111
2007 10.079
2011 10.046
2012 9.971
However, using a rolling 12-month average, the values and end-dates for the local minima are ...
2015 10.111 (31st Dec 2015)
2007 10.057 (11th Nov 2007)
2011 10.015 (17th Nov 2011)
2012 9.915 (15th May 2013)
Unsurprisingly, the current rolling 12-month average has been dropping almost monotonically for the last 6 months, and has been ticking off a few minor milestones en route.
On the 16th May, the rolling 12-month value reached 10.056 millions sq kms, thereby replacing 2007 as having the 3rd lowest local minima. (The year-end value for 2007 had been surpassed on the 1st of May.)
By the 23rd June, this value had dropped to 10.014, thus displacing 2011 as the second lowest local minima for the rolling 12-month average. (The 2011 year-end value had been passed on the 24th of May.)
As at June 30, the rolling average has dropped to 10.003, and, in the absence of any
deus ex machina intervention, when the IJIS/ADS figure for July 2nd is announced, we will see this average hit the psychologically significant figure of 10 million sq kms.
PROJECTION TIME: If the July values drop at a steady 70 thousand sq kms/day, then by July 20, the 2016 extent will be greater than that of 2015. This would produce a turning point in the rolling average with a local minima of 9.984 million sq kms.
For what little it's worth, although the low-hanging fruit went early this year, I think the July loss rate will pick up, and the rolling average will continue to decline.
How far? Je ne sais pas.