Antarctic ozone hole may have larger role in climate change

A new paper published yesterday in Science magazine claims that the Antarctic ozone hole has more influence on climate than previously thought.

The abstract reads:

Over the past half-century, the ozone hole has caused a poleward shift of the extratropical westerly jet in the Southern Hemisphere. Here, we argue that these extratropical circulation changes, resulting from ozone depletion, have substantially contributed to subtropical precipitation changes. Specifically, we show that precipitation in the Southern subtropics in austral summer increases significantly when climate models are integrated with reduced polar ozone concentrations. Furthermore, the observed patterns of subtropical precipitation change, from 1979 to 2000, are very similar to those in our model integrations, where ozone depletion alone is prescribed. In both climate models and observations, the subtropical moistening is linked to a poleward shift of the extratropical westerly jet. Our results highlight the importance of polar regions on the subtropical hydrological cycle.

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 According to the press release from Columbia University:

While previous work has shown that the ozone hole is changing the atmospheric flow in the high latitudes, the Columbia Engineering paper, “Impact of Polar Ozone Depletion on Subtropical Precipitation,” demonstrates that the ozone hole is able to influence the tropical circulation and increase rainfall at low latitudes in the Southern Hemisphere. This is the first time that ozone depletion, an upper atmospheric phenomenon confined to the polar regions, has been linked to climate change from the Pole to the equator.

“The ozone hole is not even mentioned in the summary for policymakers issued with the last IPCC (Intergovernmental Panel on Climate Change) report,” noted Polvani, professor of Applied Mathematics and of Earth & Environmental Sciences, senior research scientist at the Lamont-Doherty Earth Observatory, and co-author of the paper. “We show in this study that it has large and far-reaching impacts. The ozone hole is a big player in the climate system!” The ozone hole is now widely believed to have been the dominant agent of atmospheric circulation changes in the Southern Hemisphere in the last half century. This means, according to Polvani and Kang, that international agreements about mitigating climate change cannot be confined to dealing with carbon alone— ozone needs to be considered, too.

The authors claim, “While the ozone hole has been considered as a solved problem, we’re now finding it has caused a great deal of the climate change that’s been observed.” This would seem to downplay the role of carbon dioxide.

Be aware that this is a computer modeling study. Only time will tell if it holds up under scrutiny.

Complete paper here.

 

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