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It is too early to tell what effect these changes have at the surface, but Shepherd points out that shifting winds are likely to alter the ocean currents that circle the Antarctic. "Whatever changes have happened in the past" as the ozone hole grew, Shepherd said, "you might worry that they might change direction" as the hole is repaired. In other findings published last Thursday in Science, Simone Tilmes of the National Center for Atmospheric Research in Boulder, Colo., and colleagues analyzed proposals to combat climate change by seeding the atmosphere with sulfate aerosols designed to reflect sunlight back into space. These proposals aim to mimic the global cooling seen after the eruption of Mt. Pinatubo in 1991 spewed such aerosols into the stratosphere. But if those proposals are ever put to test, the intended cooling could come with an unintended consequence to the ozone hole. Tilmes' findings show that -- as happened with the Mt. Pinatubo eruption -- these aerosols could activate the chlorine in the stratosphere to destroy ozone. The team estimated that under the right weather conditions, injecting enough aerosols to compensate for a doubling of atmospheric CO2 could deplete as much ozone as is present in the Arctic lower stratosphere, and could delay healing of the Antarctic ozone hole by 30 to 70 years. Both researchers said not to make the ozone hole a climate villain. "We have to remind ourselves that the ozone hole is very bad for life on Earth," Perlwitz emphasized. "It is good news that the ozone hole is going to heal. What is important is that we stop injecting so many greenhouse gases into the atmosphere. That is the main evil." Related Links: Discovery News blog: Earth Impacts |
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