Global warming may increase ozone hole
Greenhouse gas emissions might postpone the anticipated healing of the ozone layer
March 29, 1999
Web posted at: 12:10 PM EST
Despite international measures to reduce atmospheric concentrations of ozone destroying halogens to protect the ozone layer, global warming may lead to a weakening of the ozone layer, according to international scientists.
A team of German, Swiss and British scientists reported in the March 26 issue of the journal Science that while future climate change is expected to heat up the lower atmosphere it is likely to cool the air at the altitude of the ozone layer in the stratosphere.
Cooler air in the stratosphere may lead to increased polar stratospheric clouds, which are believed to play an essential role in ozone hole chemistry.
In particular, the cloud particles may settle lower atmospheric layers, thereby removing trace gases which under normal circumstances lead to a deactivation of ozone-destroying chlorine.
In other words, in a colder stratosphere the sediment particles may inhibit an important mechanism protecting ozone.
The scientists say this sedimentation process is sensitive to temperature changes. This process has been known for years to lead to massive chemical changes in the trace gas distribution of the Antarctic stratosphere, which is about 10 degrees colder than the Arctic.
They conclude that conditions in the Arctic are presently at a threshold for vertical redistribution of ozone-protecting trace gases due to the precipitation of the cloud particles.
In the future, due to greenhouse gas emissions, these processes might become strongly enhanced and postpone the anticipated healing of the ozone layer over the northern polar region to late in the next century, they said.
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