Seeing the environmental forest

2013 was notable in several ways, from the record warmth in Australia to the polar vortex that gripped the Eastern US in November and December due to a weakened Arctic polar jet stream and record drought in the US state of California, along with numerous extreme weather events around the globe .

One seemingly persistent myth about the Arctic is that there is no correlation between Arctic air temperature and sea ice extent.  At first glance, that myth appears to be true, as Arctic temperatures have noticeably risen whereas sea ice extent shows little overall change. The correlation appears even worse when plotting sea ice extent versus temperature directly. Taking a closer look, however, reveals the reason for the apparently poor correlation: The large seasonal cycle in sea ice extent data.  The cycle obscures the overall trend in sea ice data—and the correlation of that trend with the trend in Arctic tropospheric temperature.  Once that cycle is removed via a 12-month moving average, the trend in sea ice extent and the negative correlation between extent and temperature is clearly revealed. The direct comparison shows that the decline in Arctic sea ice extent has accelerated as Arctic tropospheric temperature increased. Extent = 11.6846713 + -0.9...