2020 Lower Polar Vortex shrank by 8.5 million square kilometers compared to 2012 , 2020 has smallest area every year since

~The lower in altitude Polar Vortex area right above surface of Earth is warming fast
~ Even compared to 2016,  El-Nino driven warmest year in history
~It is unquestionably clear,  warming at the core of the vortex is from over all thinner sea ice

From Jim Hunt's website :

There is not much doubt about how thinner Arctic Sea ice has become.  It may be even less than estimated:

NOAA daily composites January 1 to March 19 2020,  925 mb temperature average.  2020 is clearly  the smallest vortex area by millions of square kilometers.    From this overview, there is not much guessing as to why this current winter is amongst the warmest in history.    Again note,  the smaller the vortex the colder its Cold Temperature North Poles can be. This is a distinct feature of our current climate.  What is particularly interesting is the 2012  Canadian Arctic Archipelago  crescent CTNP  zone being nearly identical to 2020,  a precursor to 2012  atmospheric pattern leading to all time lowest sea ice extent at end of summer. WD March 13, 2020