Ozone Depletion, Greenhouse Gases, and Climate Change (1989) / Chapter Skim
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3 Stratospheric Ozone Depletion: Global Processes
3 Stratospheric Ozone Depletion: Global Processes
Pages 10-18
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From page 10... ...
The Montreal Protocol represents a watershed in the way that science has interacted with policy and in the way that policy has responded to the science. The basic reason for my highlighting the science that led to the September 1987 Montreal meeting is that other speakers in this symposium will discuss what has been learned since that meeting was held.
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From page 11... ...
3. Chlorine and ozone can enter into a catalytic cycle whereby a chlorine fragment repeatedly destroys up to 10,000 ozone molecules before some other chemical process removes the fragment from the stratosphere.
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From page 12... ...
What do scientists say about these scenarios in terms of the effect of both past and future CFC releases on stratospheric ozone? In terms of the global average ozone column, the advice to the policy group was that, if a freeze could be established in the near term, there would be a loss in global average column ozone of about ~ to 2 percent over the next 75 years.
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From page 13... ...
This would lead to a warming of the lower atmosphere and surface and would constitute a significant fraction of total surface and tropospheric warming that is predicted for all of the combined greenhouse gases. Thus, even though a policy of a freeze in CFCs would minimize total column ozone loss, the predicted redistribution and consequent upper stratospheric cooling and tropospheric warming suggest that action to actually reduce the rates of CFC emissions would be more appropriate than a freeze.
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From page 14... ...
It obtains global coverage and also provides profile data that augment the limited measurements from the Umkehr ground measurements. These data show a large decrease in ozone of about 13 percent at the high latitudes above 30 km during the period of observation.
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From page 15... ...
, then a substantial reduction in emissions will be necessary. (Here, "acceptable limits" means keeping the high-latitude column ozone loss and the high-altitude ozone loss to amounts no greater than those that result from natural variability, and the tropospheric-surface warming to less than one-fourth that expected from carbon dioxide.)
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From page 16... ...
The watershed nature of the Montreal Protocol demands that we even improve on what scientists have been able to do in interacting with policymakers. While the stratospheric ozone and chlorine problem is extremely important in its own right, perhaps the most valuable lesson of the Montreal experience is an improved understanding of how the science and policy communities should interact in order to come up with a global action on a subject prior to the occurrence of unambiguously observed effects.
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From page 17... ...
Question: In putting together the protocol, how much import~ce was given to the role that CFCs play in increasing the amount of climate warming induced by greenhouse gases? Answer: The role of chlorine emissions in increasing the greenhouse gas effect was one of the motivating reasons for convening the Montreal meeting, although the primary motivation was the depletion of ozone at the higher latitudes.
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From page 18... ...
Global Ozone Research and Monitoring Project, Report No. 16, 3 vole., WMO, Geneva.
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