Why is the Antarctic cooling?
QThe Antarctic Peninsula experienced rapid warming from the early 1950s to the late 1990s, but that warming has paused as the peninsula cools instead.
New research from British scientists found stabilisation of the ozone hole, changing wind patterns and natural variability have caused the peninsula to enter a temporary cooling phase.
AWhy is Antarctica cooling down?
Professor Tim Naish, director, Antarctic Research Centre, Victoria University of Wellington, says:
This is a really interesting new study and confirms the conclusion of earlier research – cited in the news and views, that the 20th and 21st century warming trends in west Antarctica were not unusual in the context of natural climate variability of the last 2000 years.
Natural climate processes that control the timing and strength of the El Nino Southern Oscillation and the Southern Annular Mode are thought responsible for the variability.
This new paper by Turner et al focuses specifically on the temperature records of the Antarctic Peninsula, which has often been referred to as a ‘‘global warming hot spot’’.
So while some sceptics may see this paper as an apparent ‘‘debunking’’, the Intergovernmental Panel on Climate Change (IPCC) made it clear in its 5th assessment that, unlike the Arctic, overall Antarctica had not warmed any faster than the global average temperature increase since the mid-20th century, and that regional rapid warming observed on the Antarctic Peninsula could not be attributed to anthropogenic global warming.
It also noted that during past warmer-than-present climates, when carbon dioxide levels reached 400ppm or more, Antarctica did display an amplified warming pattern up to two times more than the global average.
Amplified warming of the southern polar region is thought to take longer than its Northern Hemisphere counterpart because of the role that the deep, wellmixed Southern Ocean plays as a heat sink and potentially because of the role the ozone hole plays in suppressing powerful feedbacks associated with the sea-ice retreat.
The message is that this is not a surprise, that amplified warming of Antarctica is expected and is predicted as greenhouse concentrations increase.