Good news stories on the climate beat are few and far between, and offer occasional relief from the quickening drumbeat of bad news on the climate and biodiversity front. I didn’t have to be asked twice to file this piece for the Irish Examiner on a newly published WMO report showing the slow but steady recovery of the global ozone layer. While it undoubtedly holds some lessons on tackling the wider climate emergency, there are also limits to the parallels, as I explore below. 

GLOBAL EFFORTS to tackle both climate change and biodiversity loss have been underway in earnest for at least the last three decades, yet our best efforts to date have been an unmitigated failure. Emissions continue to spiral, temperatures climb and ecosystems buckle under ever-expanding human impacts.

Ozone is a rare form of oxygen that exists in small but significant amounts in the region of the upper atmosphere known as the stratosphere. Even though it is measured in parts per billion, this molecule is the difference between life and death on the surface of our planet, as it screens out dangerous incoming solar ultraviolet (UV-B) radiation.

According to the WMO’s latest assessment report, published every four years, the phase-out of banned ozone-depleting chemicals has led to a marked recovery in the ozone layer. “If current policies remain in place, the ozone layer is expected to recover to 1980 values by around 2066 over the Antarctic and by 2040 for the rest of the world”.

Intergovernmental success in decisively tackling the ozone crisis in the 1980s “sets a precedent for climate action,” according to WMO Secretary-General, Petteri Taalas.

He added: “Our success in phasing out ozone-eating chemicals shows us what can and must be done – as a matter of urgency – to transition away from fossil fuels, reduce greenhouse gases and so limit temperature increase”.

Just how close the world came to catastrophe as a result of ozone depletion is worth recalling. Invented in the US in the 1930s, chlorofluorocarbons (CFCs) were a technological breakthrough that quickly became used worldwide in refrigerators, air conditioning units and aerosol sprays, such as deodorants and hair sprays.

By the 1970s, over a million tonnes of CFC gases a year were slowly wafting into the upper atmosphere, but since the gas was considered to be extremely safe as it is inert, few were concerned.

In 1974, a paper was published by two scientists who speculated on what might happen to CFC gases in the stratosphere, where they would be directly exposed to solar UV radiation.

They projected that one of the elements in CFCs, chlorine, would be released at high altitude as a result of being bombarded by UV radiation. It was known that a single chlorine molecule can destroy up to 100,000 molecules of ozone. Even though there was at the time little direct evidence of ozone loss to support their theory, the US Environmental Protection Agency, acting on the precautionary principle, began banning CFCs as early as 1978.

When conservative Ronald Reagan took over as US president in 1981, his administration had little appetite for science, and the regulation of CFCs was largely dropped. However, reality was about to intervene.

Four years later, scientists working for the British Antarctic Survey shocked the world with the announcement that they had discovered a massive ‘hole’ in the ozone layer covering almost the entire continent of Antarctica. This was front page news globally in 1985.

The notion of being exposed to deadly solar rays was a simple, frightening concept that gripped the public and media imagination and politicians had little choice but to act in response to a sustained public outcry.

In stark contrast, the climate crisis has long felt complex, abstract and distant and as a result, has rarely been able to command the public or media’s undivided attention.

The Montreal Protocol

With the US leading the way, within two years, the Montreal Protocol had been signed, in which many countries committed to phasing out CFCs within a decade. Since then, almost 99% of banned ozone-depleting substances have been phased out, according to the United Nations.

In a quirk of history, the inventor of CFCs, Thomas Midgley, could have chosen bromide as the active ingredient instead of chlorine. Had he done so, the entire global ozone layer would by now have been destroyed. “More by luck than wisdom, this catastrophic situation did not develop”, the late Dr Paul Crutzen noted. He and his colleagues shared the Nobel Prize in Chemistry in 1995 for their work on identifying the ozone hole.

The Montreal Protocol is widely regarded as the most successful environmental treaty in history, and reflects a time when scientific advice was broadly followed by conservative as well as progressive politicians.

A newer class of chemicals known as hydrofluorocarbons (HFCs) were developed to replace CFCs. While no threat to ozone, HFCs are extremely potent greenhouse gases, thousands of times more powerful than carbon dioxide.

An amendment to the Montreal Protocol agreed in 2016 targets HFCs for elimination, as they have the disastrous potential to add up to half a degree of additional global warming this century.

Failed climate change campaign

Given our success with ozone, why on the other hand has intergovernmental action on climate failed so spectacularly? The first crucial difference is that there were only a handful of companies involved in manufacturing CFCs, and while they initially lobbied against regulations, they eventually simply switched to less-damaging chemicals.

Carbon, on the other hand, is embedded into every aspect of our lives, from the food we eat to building materials and the fuels that power our civilisation. While CFC manufacturers had limited clout, the fossil fuel industry is the most profitable and powerful enterprise in human history, with entire economies, known as petro-states, depending on the easy profits that come from extracting and burning coal, gas and oil.

The industry has known for decades that the widespread burning of fossil fuels would, in time, cause the global climate to destabilise dangerously. US-based oil giant, Exxon, had been informed by its own scientists as far back as 1977 of the dangers, but rather than act, the company joined with other industry players to fund climate denial and disinformation campaigns.

Their tactics included smearing climate scientists with personalised attacks, setting up and funding phony grassroots groups and using lavishly funded PR and media campaigns to spread the false message that the “science wasn’t settled” by promoting a handful of fringe contrarian scientists prepared to deceive the public on the industry’s behalf.

These campaigns were highly effective, largely perhaps because they told us what we wanted to hear – that we could continue our profligate lifestyles indefinitely. These energy behemoths could of course have invested their vast revenues into a profitable clean energy transition, but sheer greed combined with ‘free market’ ideology meant this golden opportunity was squandered.

A word of warning

While the ozone success story offers a tantalising glimpse into how we might engineer a safer future by following the science, there is also a sting in the ozone tale. A 2020 study on an ancient mass extinction event at the end-Devonian period some 359 million years ago argues that the event was preceded by a sudden warming spike that directly led to massive global ozone depletion.

Researchers identified this catastrophic ozone destruction as the “kill mechanism”, but the trigger was rapid global warming. If this hypothesis is correct, our recovering ozone shield could yet be wiped out by unmitigated global warming in the decades or centuries ahead unless radical action is taken to sharply cut emissions. We have been warned.