Jaxa Antarctic Sea Ice Extent - a speculative look at the last few yearsIf you read the
https://nsidc.org/arcticseaicenews/, extract follows, you would think that not-a-lot was going on...
In the Antarctic, autumn is now in full swing, but ice growth has been somewhat sluggish through the month. At the beginning of the month, extent was between the seventy-fifth and ninetieth percentile range of the 1981 to 2010 climatology. By the end of the month, extent was within the inner quartile range and just above the median.
A longer view, starting as early as 2012, tells a different story, best illustrated by the 365 day trailing average graph attached.
Until 2012 Antarctic sea ice went above and below a trend line showing a very slow sea ice increase of around 2,500 km2 but with a meaningless correlation (R2 value less than 1%), and an average value of around 11.6 million km2.
In the nearly 4 years from Jan 2012 to mid-2015 that average increased from a low of 11.4 million to a maximum of 12.8 million km2, an increase of by 1.4 million, a rise of 13%. That maximum is way out of trend.
From mid-2015 to October 2017, only just over 2 years, that average dropped from 12.8 million km2 to 10.4 million km2, i.e. by 19%, nearly 10% a year, and again massively out of trend.
In the 2 years and 7 months since then, the average has risen by 1.26 million to 11.66 million.
This is currently just 50k above the simple long-term average and just 1k above the long-term trend, and looked at in isolation is pretty ordinaryBut the huge variations in average sea ice extent in recent years cannot be solely down to normal variations in and gradual increases in temperatures. I am tempted to think tipping points. I read that a characteristic of an energy driven system is that as it gains energy it can reach a point where it becomes unstable. Are we seeing a manifestation of this?
End of speculationclick image to enlarge
