Action on climate is effective, just look at acid rain and the ozone layer

Stuart Mathieson: International efforts can have an effect within our lifetimes

The COP26 summit raises two crucial questions: the possibility, indeed the practicality, of obtaining international consensus, and whether that consensus could translate into effective action on climate change.

Optimists can point to Joe Biden, who brought the United States back into the Paris Agreement on the first day of his administration. Pessimists, meanwhile, will note that Australian prime minister Scott Morrison has not yet committed to attending. Yet the recent history of international climate action shows that, while it might involve difficult trade-offs and political wrangling, there are two recent success stories: acid rain, and the ozone layer.

The term acid rain was first used by the Scottish chemist Robert Angus Smith in 1872. Smith took samples of rainwater in English industrial towns, and noticed that they contained large amounts of sulphuric acid, from the sulphur-rich coal fuelling the region's factories. Smith linked acid rain to eroded masonry and the lack of vegetation in urban centres. He also identified large amounts of ammonia in samples taken downwind from agricultural regions, a result of fertilisers used in industrial farming.

As chimneys grew taller, particles were transported further, and the local effects of acid rain became less obvious. A study of southwestern Sweden in 1952 did highlight high levels of ammonia, which it linked to Danish agriculture, but the relationship between industry and acid rain received little attention until 1972. That year, scientists reported rainwater observations in New Hampshire, with samples 100 times more acidic than expected. The surprising source of the pollution was the industrial midwest, more than 1,500km away.


The vast distances travelled by industrial emissions made them transnational problems. During the 1970s, Canadian forests were stripped bare, and lakes turned so acidic that they could no longer support life. Prime minister Pierre Trudeau’s ability to regulate the source was hampered by it being in a neighbouring jurisdiction and was reliant on his counterparts in Washington.

Socially conscious Jimmy Carter was amenable to a deal, but his defeat in the 1980 election put acid the rain sceptic and anti-regulation Ronald Reagan in the White House. Trudeau, a masterful diplomat, eventually convinced Reagan to admit responsibility for, and commit to ameliorating, acid rain. Amendments to the Clean Air Act, enacted in 1990, committed the US to a reduction in sulphur emissions and have been remarkably successful.

In Europe, a similar scenario played out. Norwegian and Swedish countryside suffered significant damage from acid rain, with a major source being the coal power plants in northern England. Margaret Thatcher spent several years downplaying British responsibility, but in 1986 agreed to fund desulphurisation in some of the worst-polluting plants. The heavily industrialised Black Triangle border region between Czechoslovakia, East Germany, and Poland also suffered extensive deforestation. There, efforts to arrest the damage had the added difficulty of convincing authoritarian governments to act when it was not in their interests to do so. It was not until the fall of the USSR that action was agreed, although support from the European Union's Phare programme has helped to decrease the level of pollution.

Even more remarkable is the hole in the ozone layer. In 1974, American scientists suggested chlorofluorocarbons (CFCs) from packaging, refrigeration, and aerosols could travel into the stratosphere, react with, and deplete, the protective ozone layer. Although this remained theoretical, the Carter administration led global efforts to reduce CFC use, and they were banned from US aerosols in 1978. However, in 1985, a study in Antarctica found a massively depleted region in the ozone layer. In 1986, a study suggested ozone depletion could cause a massive rise in skin cancer cases, and fearing a class-action lawsuit, the world's leading producer of CFCs, DuPont, became one of the biggest proponents of eliminating them.

In 1987, the Montreal Protocol committed 197 signatories to phasing out CFCs. Its lessons are remarkable. Global action can be rapid: it came 14 years from the first research linking CFCs to ozone depletion, and only two after it was proven. It demonstrates that applying financial and regulatory levers to industry can force innovation.

It also provided a model for future action, with developing nations being given more time to phase out CFCs and the onus placed on the largest polluters. Finally, with the ozone hole predicted to close by 2060, it shows that concerted international action can have an effect within our lifetimes.

Dr Stuart Mathieson is is a postdoctoral fellow working in Dublin City University school of history and geography