Global warming delays ozone repair
Computer modeling suggests climate change has adverse effects on protective ozone layer
A new report from Darryn Waugh of the Earth and Planetary Sciences Department and his colleagues suggests that future patterns of air circulation in the atmosphere may prevent ozone levels from returning to their normal levels.
Ozone, which absorbs dangerous ultraviolet radiation before it hits the Earth's surface, has been depleted in recent decades due to the release of various chemicals into the atmosphere.
Part of a much larger collaborative project with the NASA Goddard Space Flight Center in Greenbelt, Md., this ozone study was based on a computer model looking into future climate conditions.
The model was chosen for being a "middle of the road" scenario, according to Waugh, and factored in aspects such as the concentrations of carbon dioxide and greenhouse gasses, temperature and air circulation.
How accurate was this model? "We don't know," Waugh said. "If we take a different course, impacts could be different."
The model found non-uniform changes in future ozone concentrations in different regions of the stratosphere. In the tropical lower stratosphere, the main change is an increased speed of air circulation. This faster moving air makes it more difficult for the chemical reactions that produce ozone to occur, resulting in decreased ozone levels.
In contrast, increasing concentrations of carbon dioxide in the upper stratosphere (40 to 50 kilometers up) actually cool the region, opposite of what they do in the lower part of the atmosphere.
This cooling slows the rate of ozone destruction. As a result, the ozone concentrations here remain elevated for longer - the ozone builds up in the upper stratosphere.
So if the ozone destruction is increasing in the lower stratosphere but decreasing in the upper stratosphere, shouldn't the effects cancel out? Not exactly.
The global warming effects Waugh and colleagues observed in the model are regionally different. In the tropics, the increased circulation of the lower stratosphere wins out, and we see more ozone destruction.
Ozone, which absorbs dangerous ultraviolet radiation before it hits the Earth's surface, has been depleted in recent decades due to the release of various chemicals into the atmosphere.
Part of a much larger collaborative project with the NASA Goddard Space Flight Center in Greenbelt, Md., this ozone study was based on a computer model looking into future climate conditions.
The model was chosen for being a "middle of the road" scenario, according to Waugh, and factored in aspects such as the concentrations of carbon dioxide and greenhouse gasses, temperature and air circulation.
How accurate was this model? "We don't know," Waugh said. "If we take a different course, impacts could be different."
The model found non-uniform changes in future ozone concentrations in different regions of the stratosphere. In the tropical lower stratosphere, the main change is an increased speed of air circulation. This faster moving air makes it more difficult for the chemical reactions that produce ozone to occur, resulting in decreased ozone levels.
In contrast, increasing concentrations of carbon dioxide in the upper stratosphere (40 to 50 kilometers up) actually cool the region, opposite of what they do in the lower part of the atmosphere.
This cooling slows the rate of ozone destruction. As a result, the ozone concentrations here remain elevated for longer - the ozone builds up in the upper stratosphere.
So if the ozone destruction is increasing in the lower stratosphere but decreasing in the upper stratosphere, shouldn't the effects cancel out? Not exactly.
The global warming effects Waugh and colleagues observed in the model are regionally different. In the tropics, the increased circulation of the lower stratosphere wins out, and we see more ozone destruction.
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jace buchan
posted 2/28/09 @ 2:06 PM EST
hi my name is jace and i am i 10 grade. i am doing a 3 page paper on the affects of global warming. in this artical it talks about th increased air circulation, is this a Natural occurrence or human caused?
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