Most people already know full well about the decline of sea ice extent in the Arctic. I’m as guilty of many others who constantly check the week to week, and day to day fluctuations that are continually going on up there, but today I though that I would step back and look at the bigger picture and look at the whole of the satellite record by means of a 365 day moving average, that irons out all the noise and reveals what’s really been going on. There is no doubt that average sea ice extent in the Arctic has declined by just over 24% in those 42 years or so. The decline has been quite steady despite the occasional short lived resurgences over the years. The linear trend reveals that the Arctic has been losing over half a million square kilometres of sea ice every decade during the last forty years or so.
In the Antarctic things have been totally different. It’s interesting to see that in 1978 the sea ice extent in the Arctic exceeded that in the Antarctic, but in the last 40 years that situation has been reversed. The linear trend shows a slight rise in sea ice extent and a small gain each decade, that’s despite the hiatus that went on during 2016 and 2017, when the Antarctic lost well over two million square kilometres of sea ice in a little over two years. Since then there has been an erratic but sharp recovery in extent.
The surge in sea ice extent to record levels in the years before 2016, and the sharp crash just after it, tie in quite well with my DIY Global temperatures series for the Antarctic during that time.