I compared the actual JAXA extent data with the averages from 1980s to 2010s.
Arctic sea ice extent of 2019 is 4 days behind schedule if compared with the 2010s average. In the Antarctic 2019 is ahead by 7 days, which sums up to 11 days of difference.
These differences are bigger in comparison with earlier decades:
2019 vs 2000s: 15 days Arctic, 8 days Antarctic = 23 days
2019 vs 1990s: 25 days Arctic, 8 days Antarctic = 33 days
2019 vs 1980s: 29 days Arctic, 9 days Antarctic = 38 days
This is a difference of more than a month!
That is an interesting way to capture the trend Stephan. Perhaps we can compare the invidual decadal rates by subtracting each one from the previous decade. (I think but not sure this is kosher.)
Thus 1990s vs. 1980s: 5 more days
2000s vs. 1990s: 10 more days
2010s vs. 2000s: 23 more days
2020s vs. 2010s: 46 more?? more days (since there a doubling for each previous step)
Just a wild guess. There may be constraints on continued growth at a doubling every decade.
The Arctic-only version:
1990s vs. 1980s: 4 more days
2000s vs. 1990s: 10 more days
2010s vs. 2000s: 15 more days
2020s vs. 2010s: 20 more?? (since each prior step added about 5 days)
The Antarctic-only version:
1990s vs. 1980s: 1 more day
2000s vs. 1990s: 0 more days
2010s vs. 2000s: 8 more days
2020s vs. 2010s: 8 more?? (since previous step added 8 days)
At first glance, you might think that the big difference in the Arctic vs. Antarctic trends shows a problem with using this method. But I think it reflects an actual characteristic of the data. In the 1980s and 1990s, the Antarctic sea ice was not showing a trend from global warming.
I'm surprised that the Antarctic 2010s vs 2000s even showed an increase because I thought it was only in the last few years that Antarctic sea ice Extent was declining. (or am I completely misunderstanding the dates Stephan is citing for Antarctic sea ice?)
That possible rapid acceleration for the Arctic looks worrisome. Good thing we have smart and wise political leadership at the helm to steer us through what could be a time of difficult choices and profound but necessary changes to reduce the harm.
What... we don't have that? Uh oh.