Twenty-five years ago, there appeared two scientific papers that rocked the industrial world. One of them, by Richard Stolarski and Ralph Cicerone, said that if chlorine atoms ever got wafted up into the stratosphere, they could eat up the ozone layer. The second, by Mario Molina and Sherwood Rowland (who got the Nobel Prize for this work in 1995), said that chlorine atoms were already up there and that they came from human-made chemicals.
The chemicals were chlorofluorocarbons, known as CFCs, then widely used in refrigerators, car air conditioners, insulating foam, cleaning agents, aerosol spray cans, and fast-food hamburger wrappers. Until those two papers came out, everyone thought CFCs were benign. Only an atmospheric chemist could have imagined that they might be making mischief five miles over our heads.
The mischief consisted of munching away the protective zone of ozone that filters out most of the ultraviolet rays from incoming sunshine — the UV rays that give us sunburn, cataracts, snow-blindness, and skin cancer and would do a great deal worse, if more of them got through to us.
In the 25 years since the world received this warning, a lot has happened to demonstrate that there is intelligent life on earth. Scientists learned much more very fast about the chemistry of the stratosphere. The U.N. pulled together governments to hammer out the 1987 Montreal Protocol and several later agreements to slow and then stop CFC manufacture. Industry found other ways to do the many tasks that CFCs had been doing.
A new report has just come out, written by 305 scientists from 35 nations under the auspices of the World Meteorological Organization, telling us, basically, that the damage we did to the ozone layer was deadly serious and is not over. But we’re on our way to healing.
Here are their main findings:
“The Montreal Protocol is working.” Human CFC production has now fallen to only seven percent of its 1989 peak of 1.3 million tons. Most nations are abiding by the agreements. There is some smuggling of illegal CFCs, but it is minor compared to the damage that has been averted.
“The ozone layer is currently in its most vulnerable state.” Ozone depleting chemicals are expected to peak in the stratosphere around the year 2000. There’s a delay between the production peak and the damage peak, because it takes years for a newly released CFC molecule to work its way up to the ozone layer.
“The springtime Antarctic ozone hole continues unabated.” Ozone depletion is worse over the South Pole than anywhere else. The vast ozone hole that opens there every October in the southern spring shows no sign of closing yet.
“The late-winter/spring ozone values in the Arctic were unusually low in 6 out of the last 9 years.” There are far more people in northern high latitudes than in southern ones, so the ozone drop in the northern spring, with its measurable increase in UV radiation (about 7 percent across the mid U.S.), is cause for concern and will be for another decade or so.
“The ozone layer will slowly recover over the next 50 years.” That’s how long the chlorine already up in the stratosphere will last. Our stratospheric UV-filter is expected to be back to its 1980 state by about 2050, assuming the international agreements are followed and there are no large volcanic eruptions (which can also temporarily deplete ozone).
“Few policy options are available to enhance the recovery of the ozone layer.” We’ve already done about all we can do. We just need to keep doing it and wait and hope.
There’s one kicker in the new report. The stratosphere is cooling these days, because the depleted ozone layer is trapping less radiation up there. That means, the scientists say, that more ultraviolet light is reaching the earth, but less infrared light, the kind that does the main warming. That effect may be counterbalancing as much as 30 percent of the warming that would otherwise be expected from another of our polluting activities, our emissions of greenhouse gases. In other words, the ozone hole has been disguising some global warming. As it heals, we may be in for even more of a temperature surge than what we have seen so far.
We haven’t yet done an intelligent job of responding to the global warming problem. One reason for that is the obstinate denial of a few highly placed ultra-conservative American congresspersons, some of whom also loudly deny that there has ever been an ozone-layer problem.
To them I can only say, do your homework. Read that report from the 350 scientists (Scientific Assessment of Ozone Depletion: 1998, published by the WMO). It is written in clear language, and it corrects the many misconceptions you and your talk-radio friends have been circulating. There’s an especially good “frequently asked questions” section at the beginning. I have never before seen such thoroughly documented scientific proof of an environmental problem. The science is not in question. And the story of the past 25 years shows that repairing global-scale environmental damage may be a challenge, but it’s possible. We’re up to it. With the ozone layer we are doing it.
We could do it with the climate too.
