A warm weather warning

Sherwood Rowland has seen his work on the dangers of aerosol sprays result in a worldwide ban. But, he tells Ayala Ochert, he fears it will take an environmental crisis before governments take action again.

Whatever happened to the chemicals known as chlorofluorocarbons - once the basis of a $200 billion aerosol spray industry? In the 1980s, the link between CFCs and the hole in the ozone layer was a burning topic. Press reports carried news of impending doom, and the government even published advertisements dramatically announcing to the country: "You have been warned!" And then, nothing.

Though the end of the story has received much less attention than its beginning, it is no less remarkable. In 1996, thanks to a worldwide ban, CFC production ceased. The tale of how the world went from news of a potential danger to a total ban in 17 years is also the story of the career of Sherwood "Sherry" Rowland.

In 1995, Rowland shared a Nobel prize with his former postdoctoral researcher Mario Molina for alerting the world to the potential of CFCs to severely damage the stratospheric ozone layer that shields the earth from the sun's ultraviolet rays - and so threaten life on earth. The parallels between the events that led to the ban on CFCs and manoeuvres to limit carbon dioxide emissions, which contribute to global warming, have not been lost on those seeking limitations or those who oppose them.

Back in the early 1970s, Rowland had spent several years setting up a chemistry department at the new Irvine campus of the University of California, and he was getting restless. While looking for something new to research, he heard that the British scientist James Lovelock had detected significant amounts of CFCs in the atmosphere.

CFCs, first created in 1928 by chemical manufacturer Du Pont, were designed to be inert, to react with nothing. "But as chemists we knew that they would react eventually," Rowland recalls. "I wondered what would happen to them."

What he and Molina found was that the intense ultraviolet light of the upper stratosphere would finally get to CFCs, forcing them to release their chlorine atoms and initiate a chain reaction. "The significance of this chain reaction is that one chlorine atom could take out 100,000 ozones, and when you multiplied that by the million tons of CFCs released each year, you had a serious problem," Rowland says. "We realised within two-and-half months that what had been an interesting intellectual exercise was a major environmental problem."

One night, his wife asked him how his work was going. Rowland replied despondently, "Very, very well. But it looks like the end of the world."

The next 15 years were a rollercoaster of emotions, as the government and scientific committees that met to discuss the problem were pulled one way by fear of a global crisis and the other by the multi-billion dollar industries that relied on CFCs. "The idea that spraying underarm deodorant could contribute to a global environmental problem was seen by the business community as environmentalism gone mad," Rowland says.

Despite this attitude, things initially seemed to go well when the United States, Canada, Sweden and Norway all agreed to ban aerosol sprays containing CFCs as early as 1978. But that early progress was soon hindered by a powerful industry lobby and a new government in the US, led by Ronald Reagan, determined to dismantle environmental legislation. As atmospheric scientists tried to refine their experimental models, their computers creaking under the strain, predictions of ozone losses went up and down on a rollercoaster of their own, adding fuel to those who wished to highlight the uncertainty of atmospheric science.

When it came to the second phase - what to do about CFCs used in applications other than aerosols - the US Environmental Protection Agency seemed to adopt a "wait-and-see" policy. The rest of the world meanwhile was still pondering an aerosol ban.

As more details of the hundred or so chemical steps involved in breaking down CFCs were discovered, and better computers became available for modelling the atmosphere, something happened that no scientist could have predicted. In 1985, the Cambridge-based British Antarctic Survey reported a massive "hole" in the ozone layer above the Antarctic. For part of the year, ozone levels were 60 per cent lower than they had been previously, and a loss of 10 per cent was recorded for the rest of the year.

The world was shocked into action, and in 1987 the United Nations drew up the Montreal Protocol calling for a 50 per cent reduction in CFC emissions by 1999. As more evidence gathered implicating CFCs, that quickly became a total ban. In 1992, the deadline for the time by which the world would cease to allow production of these chemicals altogether was adjusted to 1996.

"If you had asked me back in December 1973, would we have an international agreement to ban CFCs in 13 years and a total ban in 17 years, I would have said it was not very likely," Rowland says. "When we started out we said, this is what will happen in the future. But suddenly we were talking about a 50 per cent (ozone) loss in Antarctica today. It's the timescale that drove people to action. The question now (in talking about climate change), is what is the geophysical or biological equivalent of an Antarctic ozone hole, something so stark that it really makes people sit up and take notice?" Rowland offers two possibilities - the shutdown of the Gulf Stream, the large current of warm water flowing northeast across the Atlantic, or a permanent state of El Ni$o, the change in sea currents off South America that has had devastating climatic effects. The last time the Gulf Stream failed, about 11,000 years ago, Northern Europe was plunged into a mini ice age. The effect of a permanent El Ni$o would be no less serious. Although Rowland is careful to say that these are not predictions, he points out that they are not outlandish suggestions either.

Hugh Pitcher of the Pacific Northwest National Laboratory agrees that it may take such an event before we see any serious action on global warming. "I'd like to think that we've gotten smart enough in politics that we don't need a catastrophe to do something, but I'm very much afraid that it will take a crisis. But if we wait, it may be a case of closing the barn door after the horse has bolted. The effects of climate change may be irreversible, or at least the timeframe for recovery might be measured in hundreds of years," he says.

He disputes the parallels with CFCs and the ozone hole. "With CFCs, there was a disaster waiting to happen. But we don't have a comparable clear message at this time for climate change. It's not a problem that responds well to simple prescriptions," Pitcher contends.

According to Ragnar Lofstedt at the University of Surrey, this lack of a clear message about climate change has left the public confused and ambivalent. "The public has been receiving mixed messages, and people are less concerned about climate change than they were ten years ago. But how can we reduce carbon dioxide emissions if the public doesn't believe there is a problem?" he asks. "Policy-makers need to take a much stronger stand - they have been incredibly weak. A strong policy message would be the way forward, to get the public to take the problem seriously."

Rowland is less optimistic about changing public attitudes: "A lot of people get their information from radio talk shows, and they just tune to the one whose politics matches their own and take whatever science comes with it." All but a handful of climate scientists believe that global warming is already upon us and they believe that sceptics have been given too much airtime. "There has been remarkably little talk of the fact that every month of 1998 was the warmest since reliable records began about 125 years ago. We have broken the record month after month - what would you like to convince you that we are experiencing global warming?" Rowland asks. "If you start flipping a coin and it comes up heads 20 times in a row, you start to suspect that it's not an evenly weighted coin."

* FIRST A BLOOM,THEN DIE-BACK

It may seem paradoxical, but some of the early signs of global warming could be favourable. Analyses for the US Forestry Service, conducted by Ronald Neilson, show that some areas of the world may become very lush. "One of my big concerns is that that might engender complacency. People might think 'this is great', but we should not be lulled by these beneficial effects early on."

Neilson's models show that despite early lush growth in some areas, most forests will succumb eventually to higher temperatures and experience "drought-induced die-back".

"There has been too much emphasis on bet-hedging and not enough clear statements. Scientists need to present their work in a way that gives a strong message to the public," Neilson says. He adds his own clear message:

"There could be serious consequences of climate change for forests."