Why phasing out chlorofluorocarbons proved a much easier sell than have been moves to cut back on greenhouse gases

By Janet Raloff

Web edition: November 8, 2011

On November 7, ozone and climate scientists met in Washington, D.C., to discuss whether the history of stratospheric ozone protection offered a useful case study about how to catalyze global action on carbon dioxide and other greenhouse gases.

Their simple answer: No.

Ozone-damaging chlorofluorocarbons — or CFCs — represented a special case. Such swift global action following recognition of a scientific threat is unlikely to be witnessed again, argued researchers attending the International Year of Chemistry’s Symposium on Stratospheric Ozone and Climate Change.

Even with CFCs, it had been anything but a certainty in the mid 1980s that the public would take action, recalls Mario Molina, one of a trio of physical chemists who would win a Nobel Prize (a decade later) for identifying CFCs’ risk to ozone.

But then the Antarctic ozone hole emerged.

It offered the most graphic confirmation imaginable that scientists’ had not overblown concerns about CFCs’ threat to the health of Earth’s ozone layer. Just two years after the 1985 discovery that an ozone hole was seasonally recurring in the stratosphere some 14 to 20 kilometers above Antarctica, nations around the world signed the Montreal Protocol ozone-protection treaty.

“In some sense, we were lucky with the stratospheric ozone problem that something really big happened,” says Molina. Within a few years of the hole’s discovery, ozone concentrations within a critical zone of the atmosphere over Antarctica would annually drop by up to 99 percent. He says it offered “what we could call a smoking gun.”

Linking rising atmospheric concentrations of chlorine from CFCs to ozone’s disappearance was so clear and straightforward, he says, that afterward, no one questioned the strength of the science. “We probably don’t have the equivalent yet with climate change,” he points out.

Robert Watson agrees. Science pointing to ozone impacts from CFCs was not only something that the public and policymakers could understand, but it also compellingly drove home recognition of the threat these pollutants posed to life on Earth, says this chief science advisor to the United Kingdom’s Department for Environment, Food and Rural Affairs (with appointments at the World Bank and University of East Anglia).

In short order, Watson says, powerful new and emerging science triggered “a change in a global policy framework. This is something we should aspire to [in other areas — like climate change and threats to biodiversity],” he says, “but recognize we are not likely to see this on any other issue.”

One reason for that, maintains Susan Solomon, another pioneer in chronicling the Antarctic ozone hole’s emergence, is that “people understood the message that changes in the ozone layer would increase the incidence of skin cancer.” Here, the atmospheric scientist emphasizes, “we were talking about impacts in our own time.”

There’s no doubt that some evidence for climate change already exists, she says. “But let’s face it: It’s just not at the same level of immediacy and personal impact that we had with ozone.”

Climate’s threat is emerging much more slowly, in tiny incremental changes that may be hard to distinguish against a backdrop of natural variability in surface temperatures, in polar and glacial ice cover, and in extreme weather events. Climate change is expected to deliver really big changes, but these may not play out convincingly for decades — even perhaps, for a century. Moreover, some residents of inland, temperate regions aren’t even convinced yet that a somewhat warmer world might not be a good thing.

Perhaps the biggest impediment to galvanizing public support for action on climate is the breadth of the contributors, Solomon and others argued at the meeting. With CFCs, only a few manufacturers and sectors of the economy were responsible for the offending pollutants. This meant a relatively small number of players could effect change by tweaking or substituting technologies.

By contrast, global warming and its attendant changes stem from pollutant emissions contributed every day through myriad activities by virtually every human alive.

Adding to the complexity of addressing the problem: Those who stand to feel the pain first — such as residents of low-lying islands — may have contributed little to the problem. And the populations who stand to be most impacted are those who haven’t even been born.

“What that means,” Solomon says, “is that we really need to open up an intergenerational discussion.” And “we have to open a new discussion on ethics.” If people don’t accept that there will be some serious disparities between those who are most contributing to the problem and those who will be asked to pay the highest price, she says, “you can communicate the science until you’re blue in the face” and still make little to no headway on galvanizing global action.

Finally, Molina says, there is another important disparity in the way the public and policymakers have viewed climate versus stratospheric ozone threats. It involves perceptions and politics.

When there seemed to be an impasse on action over CFCs, the U.S. president — a Republican — weighed in and convinced the Senate to ratify action. Other countries followed suit. President Obama, Molina observes, has failed to convince the majority in Congress that climate change poses a national security threat. For many in Congress today, “It’s politically incorrect to talk about climate change,” Molina says — with a large share of lawmakers “dismissive” of the science and its message.

And critics of climate science have been “misrepresenting” the strength of the science, Molina contends. They’ve portrayed the body of evidence on climate change as a “house of cards. So that means that if you find something wrong with any particular issue (you could call this cherry-picking) the whole thing will crumble.” In fact, he argues, “that’s not the way science works.”

He likened climate science instead to a large, unfinished jigsaw puzzle. Even with dozens of pieces missing or a piece inserted temporarily in the wrong spot, most people will soon discern the focal subject — be it a cat, or landscape or mound of cookies. What scientists need to communicate, Molina says, is that “the basic science is not in question.” Details on timing and magnitude of changes may still vary. But the science is impressively sound.

And although scientists should not prescribe action on climate or any other social policy, Watson says, researchers can — and should — weigh in as individual citizens on how to interpret science for policymaking.

Molina agreed, mentioning an instance where he and his colleague (and fellow Nobelist) Sherwood Rowland had been conflicted about whether to speak up on threats to stratospheric ozone. Recalls Molina, “I remember [Rowland] very clearly posing the question: If not us, who? And if not now, when?”