Repairing ozone hole may actually harm Earth's climate systems: Science study news
16 June 2008

For years, conventional wisdom has been that closing the hole in the ozone layer above the Antarctic would solve many of mankind's weather problems, besides protecting species from harmful ultraviolet radiation. However, a recent study has turned that wisdom on its head by claiming such a move may actually be detrimental to earth and its inhabitants by heating up the freezing continent and thereby accelerating global warming.

The study led by scientists from Columbia University, and published in renowned scientific journal Science on 13 June, found that if the ozone hole were to recover in the next 50 years as predicted it would affect the flow of winds called the westerlies around Antarctica. This change in the direction of the winds might play havoc with the existing models of climate in the Southern Hemisphere.

The finding is in contrast to the observations made by the report of the Intergovernmental Panel on Climate Change (IPCC), which didn't include ozone recovery in its climate modelling

"Although the rest of the climate is warming up . . . there's been a cooling over the Antarctic plateau and a speeding up of the winds around the edge of the Antarctic," said University of Toronto professor Ted Shepherd, who co-authored the paper with scientists from the US, Switzerland and Japan.

"As the ozone hole heals, then we have more ozone, the ozone is coming back. And that will trap more heat, so it'll be a warming effect."

Another co-author, Lorenzo Polvani from Columbia University said that the westerlies are responsible for "locations of storms, dry zones and deserts, the ice and the ocean circulation as well as the carbon uptake of the oceans'', and any temperature increase would cause these winds to shift their direction towards the equator.

This, in turn, would have wide-ranging, and possibly catastrophic, effects in the climate systems of the Southern Hemisphere, with countries near the Equator more at risk. India, obviously, is one of them.

The Earth's ozone layer is in the lower stratosphere, which is just above the troposphere (from the planet's surface to a height of about 12 km). It absorbs harmful ultraviolet rays of the sun. Scientists discovered the ozone hole, or rather a thinning in the layer, in 1985. It goes through yearly cycles and is at its thinnest from late August to October, during the Southern Hemisphere's winter.

Widespread use of household and commercial aerosols, containing mainly chlorofluorocarbons (CFC), till the late 1990s, led to significant ozone depletion, putting the public health at risk. The production of CFC was phased out across the world in accordance with the Montreal Protocol, signed by 191 countries.

Some view the treaty, with its differing targets for different countries, as one of the most successful international agreements on the environment. It was amended last autumn to add new ozone-depleting chemicals, to force all signatories to make new emissions cuts, and to saddle rich countries with the deepest and earliest targets.

Last fall, the European Space Agency said the ozone hole shrank 30 per cent compared with 2006's record size. Last year's ozone loss peaked at 27.7 million tonnes, down from a loss of 40 million tonnes from the year before.

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Repairing ozone hole may actually harm Earth's climate systems: Science study