Study: Greenhouse Gas Buildup Could Encourage Arctic Ozone Holes
NEW YORK (AP) _ Researchers said today that ozone ″holes″ similar to those now detected over Antarctica may start forming over the Arctic if people pour enough carbon dioxide into the atmosphere.
The holes might begin to appear in 50 to 75 years, given current trends in carbon dioxide emissions, said researcher John Austin.
Carbon dioxide, a gas given off by the burning of fossil fuels, is already a major culprit in forecasts of global warming.
The Arctic holes would probably be less severe than those now seen over Antarctica, and would form only about once every five winters at most, when meteorological conditions were right, Austin said.
An ozone hole is a severe depletion of ozone for a period of time in a particular place, as occurs over Antarctica. The ozone is destroyed by chlorine-bearing pollutants.
The effects of Arctic ozone holes are unclear but ″any alteration we’re making to the atmosphere is something to be concerned about,″ he said.
The ozone reduction would expose Arctic wildlife to more ultraviolet radiation and might mean transient increased exposures for people elsewhere in the northern hemisphere, he said. Ultraviolet radiation promotes skin cancer and cataracts.
The new study is a computer simulation that suggests ozone holes could appear over the Arctic if atmospheric concentrations of carbon dioxide were doubled.
The work is reported in today’s issue of the journal Nature by Austin, a principal scientific officer at the government’s Meteorological Office in Bracknell, England, his colleague Neal Butchart and Keith Shine of the University of Reading in England.
Austin called the study conclusion plausible but ″possibly no more than that.″
Jerry Mahlman, director of the National Oceanic and Atmospheric Administration’s geophysical fluid dynamics laboratory at Princeton University, said his own research has produced similar findings.
He said the odds of Arctic ozone holes as severe as those seen in the Antarctic were probably two out of three within the next 50 years. That risk is ″purely a guess, but it’s big enough that you ought to be thinking about it,″ he said.
Rolando Garcia, a senior scientist with the atmospheric chemistry division of the National Center for Atmospheric Research in Boulder, Colo., said Arctic ozone holes are possible in the next century from time to time under unusual conditions.
″I would not stake the house on the fact that this would happen, but on the other hand I would not be surprised if something like this did happen,″ he said.
But James Friend, a professor of atmospheric chemistry at Drexel University in Philadelphia, said the risk of Arctic ozone holes would be temporary. Because of an international treaty called the Montreal Protocol, he said, chlorine in the air will eventually be reduced enough to prevent Arctic holes from forming.
Austin’s study concludes that a doubling of carbon dioxide would lead to a cooling of the lower stratosphere over the Arctic, which would encourage the formation of what scientists call polar stratospheric clouds. That would promote ozone destruction by chlorine because of chemical reactions on the surfaces of the cloud particles, as happens over Antarctica, Austin said.
Ozone itself warms the stratosphere, so as it disappeared the stratosphere would cool still more, accelerating ozone destruction, he said.
An ozone hole could affect people outside the Arctic when it broke up in early summer, he said. Large chunks of ozone-poor air could float over populated areas, temporarily increasing ultraviolet radiation below, he said.