Bored Wombat wrote:
small technical point; Isn't it winter in the Antarctic now? and don't we know why antarctic sea ice is expanding in the summer anyway?http://news.nationalgeographic.com/news ... vironment/
Some people try and argue that it's the Ozone Hole that has created circulation changes that have managed to cool Antarctica over the last 30 years,
I think that the circulation changes are what has insulated Antarctica (apart from West Antarctica) from global warming explains well the (geographical) distribution of the sea ice build-up and loss in Antarctica. I believe that there is evidence that ozone plays a part in the circulation changes, but also evidence that it has not.
but I don't buy that explaination, especially since the Ozone Hole has recovered somewhat recently, and we have continued to see an increase in Antarctic Sea Ice.
Depending on your meaning of "somewhat". It is still near the deepest and and largest it has ever been, give or take only a few percent, whereas the minimum O₃ concentration in the hole is still half what it was in 1979.
Perhaps it is the same reason for why the Arctic Sea Ice is declining... the oceanic oscillations.
I believe the cause of the declining Arctic sea ice is much less complicated. It is attributed to anthropogenic global warming. If it were due to oscillations, it would be oscillating, not declining.
Ozone may have contributed to the cooling of Antarctica, but I think that we need to understand all of the processes first, before we say things with absolute certainty.
Stratospheric Temperatures have started increasing recently (since 1995) which could represent a recovery in the Ozone Layer (Liu and Weng 2009
I also think that Ozone Depletion is far more complicated than what most people make it out to be. Anthropogenic CFCs had played a major role in Ozone Depletion, but there were also major natural components like Solar Proton Storms that also depleted the Ozone layer.
I think that most of the warming in the Arctic is probably due to regional climate change up there amplified by Arctic Amplification, but you can not deny that natural variability has played a significant role in Arctic Sea Ice depletion. Various studies that I have read estimate the contribution from natural variability to sea ice decline to be around 40-50% or so.