There's lots of good news in the recently released "Scientific Assessment of Ozone Depletion 1998," a report prepared every four years in accordance with the Montreal Protocol. The ban on substances that deplete ozone is working! Chlorine and Bromine levels are declining in the lower atmosphere and will peak and begin to fall in the upper atmosphere soon, perhaps next year.
The decline in mid-latitude ozone in both hemispheres has not been as bad as was predicted in the last assessment four years ago; and bromine, while not well understood, is not nearly as destructive to ozone as was thought.
There's reassuring news. Scientists have a firm understanding of the way chlorine and ozone interact in the upper atmosphere and have developed computer models that are in agreement with observations. They also have a good understanding of the relationship between declining ozone, clouds, particle pollution, reflectivity and increased ultraviolet radiation from ground based measurements. In addition, they have developed methods of estimating large scale changes in ultraviolet radiation using satellites.
There's the same old news about the springtime Antarctic Ozone Hole. It hasn't changed much since the early 1990s because there is almost no ozone left to destroy.
There's some worrisome news about the periodic, massive ozone losses over the Arctic. (The Coastal Post is one of the very few sources of this information.) The last six out of nine winters have been very cold and a drop in just a few degrees in temperature crosses a threshold that starts processes that efficiently destroy s ozone. Although it will be hard to predict what will happen in high northern latitudes, where hundred s of millions of people live, the implication is that vulnerability to increased ultraviolet radiation will increase for the next decade or so.
There is also a better understanding of the role of ozone loss in cooling of the stratosphere and how this has offset the increase in temperature due to the increase in "greenhouse gases." This means that the temperature structure of the atmosphere has been changed.
But then the really bad news starts. "The climatic impact of the slowing of mid-latitude trends and the enhanced ozone loss in the Arctic has not yet been assessed." The report doesn't say it, but there is serious speculation that the massive currents of air that move from the tropics to the poles, have changed-in just a few years-just flipped, so to speak, like a light switch from "on" to "off."
NASA scientists and others are involved in a crash program called "SAGE III Ozone Loss Experiment" or SOLVE to find out what is going on over the Arctic this winter. It is not exactly a secret but, really, it is. One can't blame government scientists considering that last year, after years of planning and millions of dollars spent, the House of Representatives defunded the Department of Agriculture's entire budget for its ground base ultraviolet monitoring program. Why? Who knows! (Well, one can guess they don't want to know what is going on so as not to be disturbed.)
The bad news continues: "...the maximum ozone depletion is estimated to lie within the current decade or the next two decades, but it's identification and the evidence for the recovery...lie still further ahead." This means the best guess for when the worst will come is from 2020-2030! That's a long way off. And what will happen in the meantime? Is there any preparation? Does anyone care to know?
Another part of the report on environmental effects is due later this year.
And (one could have guessed this, knowing how hard it is to get healthy), it will take much longer for chlorine and bromine to disappear from the atmosphere than it took to put them there.
As if that isn't bad enough, explosive volcanic eruptions, such as occurred recently with El Chac—n in Mexico and Mount Pinatubo in the Philippines will dramatically increase the loss of ozone. We usually have a large explosive volcano every ten years. So we can look forward to four or five while the ozone layer worsens and four or five after the "recovery" begins. From this, it seems like it will be very hard to detect any sign of the recovery, and that's what the report says.
But now comes the "zinger". "Detection [of the recovery] ...could be achievable early in the next century if decreasing chlorine and bromine were the only factor... increases in other gases important in ozone chemistry such as nitrous oxide, methane and water vapor and climate change will influence the recovery of the ozone layer"
In discussions of climate change, scientists usually speak of changes which occur within 10,000 years as "rapid." So climate change within a few decades must be spoken of as catastrophic! A sudden massive change with what went before.
What will this mean for you and me, and the other creatures who share this planet with us during the next fifty years of vulnerability?
A prominent scientist is quoted in EOS, the newspaper of the American Geophysical Union, as saying the Summary is "almost surreal." He also states there is no coordinated federal program to monitor the biological impact of increased ultraviolet radiation.
(Note: If readers come across any print or broadcast media report on this subject, please write the Coastal Post or contact Jim Scanlon at [email protected] , or leave a message at 415 485 0540).