Oceanic carbon sink could be weakened by the ozone hole

Evidence presented in France seems to indicate that the hole in the ozone layer above Antarctica impairs the ability of the Southern Ocean to absorb carbon dioxide of the earth's atmosphere.

The oceans of the Earth are the largest absorbers of carbon dioxide on the planet. The Southern Ocean is thought to take up more than 40% of the carbon dioxide absorbed by oceans, according to Andrew Lenton, a marine biologist at the Pierre and Marie Curie university in Paris, France. In theory, Nature reports, the more carbon dioxide the atmosphere contains, the more the oceans should absorb. This is elementary chemistry all of us know from grade school. However, recent measurements have shown that the surface waters of the Southern Ocean actually contain more carbon dioxide than expected. This also makes them more acidic, as logic would predict. The amount of CO2 that is being absorbed is also flattening out at this time. Lenton says that stratospheric ozone damage was missing from the models so far. Yet, it is thought to have an effect on the strengthening of the Southern winds, alongside the effects of greenhouse gases on the climate. He thinks that these stronger winds are causing ocean currents that bring carbon that is stored in the deep ocean up to the surface. Lenton and his colleagues have built simulations of the Southern Ocean that take the effect of ozone into account. By including the ozone hole in the model, they were able to reproduce the feeble absorption of carbon in the Southern Ocean that oceanographers have measured. There are other viewpoints, however. Researchers from the Leibniz Institute of marine sciences in Kiel, Germany say that they question the changes in ocean currents shown by models such as that made by Lenton and that oceanographic data provides no evidence for these changes. Lenton sounds quite conciliatory by suggesting that the currents themselves are not really the issue, the absorption of carbon is. This is clearly an ongoing story on which the last word has not yet been said.