The image above shows ice extents for yesterday, day 244, from 2007 to 2017. Particularly interesting is the variation in the CAA (Canadian Arctic Archipelago), crucial for the Northwest Passage. (The region is located north of the word “Extent” in gold.) While 2016 was a fine year for cruising with the passage completely open at day 244 that was not the case in 2014, and this year also has places frozen solid. By September 1, ice is still clogging some channels.
The graph of August NH ice extents shows 2017 has remained above the decadal average in recent days. (Ten-year average is for 2007 to 2016 inclusive).
This year is now 600k km2 greater than 2016 and exceeds the 10 year average by 50k km2. SII (Sea Ice Index) 2017 is closer now, only 200k km2 lower. 2007 is running 400k km2 lower. A previous post Beware the Arctic Storms of August discussed how late summer storms have dramatic impacts, and the graph shows both 2012 and 2016 plummeting in late August. Note that just 2 weeks ago 2012 was tied with 2017, and then lost 1.6M km2. 2016 lost 1.3M km2 in the same period.
The table below compares 2017 with 2007 and the 10-year averages for Arctic regions.
2017 has deficits mainly in BCE, especially Beaufort Sea, but those are more than offset by surpluses in Central Arctic and CAA (Canadian Arctic Archipelago). As shown in the post Arctic Heart Beat Central Arctic and CAA are the two regions providing most of the ice extent at annual minimum.
Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:
MASIE is rigorous, reliable, serves as calibration for satellite products, and continues the long and honorable tradition of naval ice charting using modern technologies. More on this at my post Support MASIE Arctic Ice Dataset