Weatherdem's Weblog

Bridging climate science, citizens, and policy

Recent Antarctic Cooling and Future Antarctic Warming

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One fantasy climate change deniers and delayers have latched onto is that Antarctic cooling proves climate change in the form of global warming isn’t occurring. Their arguments noted that Arctic melting and Antarctic freezing of water wouldn’t change sea levels, etc. Which isn’t as true as they’d like it to be: sea levels rose throughout the 20th century and have continued to do so this century. In addition, warming has occurred at the edges of the Antarctic peninsula, resulting in the breakup of very large ice sheets that have acted as a bottleneck for ice flows from the higher peninsula.

A new research paper (by actual scientists, btw) proposes a rationale for cooling in the Antarctic interior and how that cooling might be nearing an end. The cause of cold air maintenance: the ozone hole. The hole’s formation every austral spring has kept the interior cold because it decreases the thickness of the stratosphere. Less ultraviolet light is absorbed, circulations are thus set up in a way that allows temperatures to stay cooler than they otherwise would, especially in the presence of the increased greenhouse gas concentrations.

Because of the ban on chlorofluorocarbons, ozone in the Southern Hemisphere isn’t being broken down as much and ozone concentrations are forecasted to slowly recover this century. As they do so, they will increase the thickness of the stratosphere and absorb more ultraviolet light. That’s mostly a good thing as far as reducing the risk of damaging DNA in life forms. However, circulation patterns are also forecasted to completely reverse. Cold air would no longer be trapped over the Antarctic peninsula. In fact, as far as the Southern Hemisphere goes, Australia could get even warmer and South America wetter if patterns shift as expected.

The authors made use of a chemistry climate model, which is different than the general circulation models used in the Intergovernmental Panel on Climate Change’s recent work. Those GCMs need to have this and other recently researched items included so that more comprehensive analyses can be made. If the CCM results come to pass, the 21st century could experience rapid warming and ice loss at both poles.

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