As I understand it, GCMs say that ice extent at both poles should be reducing as global warming hits the poles in advance of the rest of the planet. The increase in Antarctic sea ice is therefore another question mark over the veracity and trustworthiness of climate model output.
That's the way I understand it, anyway. According to this article at The Conversation, I'm completely wrong. The increase in extent is due to changes in the Southern Annual Mode, a sort of El Nino of the Antarctic.
Here’s the kicker: the strengthening of SAM over recent decades has been directly linked to human activity. Since the 1940s, ozone depletion and increasing greenhouse gases have caused the westerly winds to intensify and migrate south towards Antarctica. The net effect of this drives sea ice further north and increases its total extent.
There is still plenty of great work ahead to improve our understanding and modelling of Antarctica’s climate, but a basic message is emerging. Far from discounting climate change in the Southern Hemisphere, the apparent paradox of Antarctic sea ice is telling us that it is real and that we are contributing to it.
So this means that the models don't recreate the Southern Annular Mode then?