The death of former president Jimmy Carter has unleashed a wave of tributes far beyond those given to most former leaders. Many are focused on his unique post-presidential career, but his four years as president, judged a failure at the time, have undergone a considerable reassessment. Yet missing from almost all this commentary is the fact that much, perhaps all, of the planet might be uninhabitable today if it were not for Carter’s most overlooked achievement.

IFLScience has highlighted one of Carter’s great post-presidential achievements – the campaign he led, now on the verge of success, to eliminate a terrible disease. We’re also one of several sites that noted the story of his (much earlier) prevention of a nuclear meltdown, saving many lives in the area. 

Significant as both these are, they’ve affected far fewer people than Carter’s role in heading off the destruction of the ozone layer, on which most of life on Earth depends. Yet this has been almost entirely forgotten. The 1987 Montreal Protocol is famous as the time the world got together and faced down a threat to humanity’s survival, phasing out chlorofluorocarbons (CFCs) and other gases that damage stratospheric ozone. Much less well known are events a decade earlier, without which Montreal would have been far more difficult, if it had happened at all.

Whereas Montreal saw political leaders from around the world come together to act like responsible planetary stewards, in the previous round it was Carter, with help from the US congress, who led the way while most of the world ignored the problem.

There might be a problem

The story starts in 1974 when Professor F. Sherwood Rowland proposed that CFCs, whose use was rapidly expanding, might pose a threat to the ozone layer. Rowland would subsequently share the 1995 Nobel Prize for Chemistry for this work, but at the time, CFC manufacturers hit back that the claims were “purely theoretical”. Technically speaking they were right. No one really knew if CFCs would actually have these effects in the upper atmosphere, a region of the planet we had barely begun to study.

Unfortunately, others pointed out, if the theory was right, damage to the ozone layer would expose the surface to so much ultraviolet radiation, little life would survive above ground or in the upper layers of the ocean. Even lifeforms not directly under threat depend on more vulnerable species for food or pollination – total ecosystem collapse was a real possibility.

Doing nothing would be the ultimate gamble.

The manufacturers established lobby groups arguing no action be taken until we had proof. DuPont’s chair called the idea CFCs might damage the ozone layer “science fiction”.  Carter, and the majority of the US Congress, feared by the time the evidence was in it might be too late.

Amending the Act

The outcome was well short of the level of action taken at Montreal. Nevertheless, Carter signed amendments to the Clean Air Act, banning the use of CFCs for certain uses where safer alternatives were readily available, most famously spray cans. More importantly, the legislation set the stage for future bans for uses such as refrigeration, where no alternative existed at the time. US chemical manufacturers, led by DuPont, made hyperbolic claims about how economically ruinous the decision would be, and how irreplaceable CFCs were for many uses.

Once the legislation passed, Carter had the Environmental Protection Agency pursue it vigorously. Now the incentives had changed, manufacturers quietly set about finding alternatives, even as they continued to voice opposition. When Ronald Reagan defeated Carter at the 1980 election his administration refused to implement the Act, and his energy secretary suggested people wear sunscreen instead of keeping the planet habitable. However, finding replacements turned out to be much easier than expected. DuPont was well on the way to developing alternatives for many uses by the time the it became clear the laws wouldn’t be enforced.

Few other countries were as proactive, but the use of safer chemicals spread from the world’s biggest market to some extent.

Finding the hole

In 1985 the stunning discovery was published that CFCs were indeed depleting the ozone layer, with the damage concentrated over Antarctica in winter. Each southern spring, lower latitudes would be exposed to major increases in radiation as the hole broke up.

Without the American ban on the use of CFCs in aerosols there would have been far more ozone-destroying chemicals in the atmosphere by this point. The annual hole would have been larger, and the consequences for life around the edge of Antarctica far more severe. 

However, Carter’s biggest contribution was the patents for safe refrigerants.

Instead of being the prime opponents of action, DuPont were now in favor of a CFC ban – they were the ones with the solution, after all. Environmentalists and scientists discovered how much easier it is to win when your biggest enemy suddenly joins your side. The agreement signed at Montreal got things moving, but a series of updates and subsequent treaties turned the threat around. 

Were it not for Carter’s work the ozone layer would already have been in a much more degraded state, but more importantly the world might have spent years failing to act because there were no suitable replacements.

We can’t know exactly how many millions of tons more damaging chemicals would have been released in the meantime, let alone calculate the damage they would have done. At minimum we can say that a great many more humans and animals, particularly for those living in the Southern Hemisphere, would have died of skin cancer without his actions.

Moreover, we know that life throughout the oceans depends on plankton that originate off Antarctica and are vulnerable to increased UV exposure. Even life on land apparently unconnected to the oceans often depends on nutrients brought onshore by birds that feed on fish, which in turn depend on vulnerable plankton. 

Ozone depletion accelerates global warming, so Carter’s actions also made a substantial contribution to the fight against climate change.

Just how much extra UV would be required to cause the collapse of the global food web isn’t known, and may never be. No one can state with certainty that failure to act in Carter’s time would have caused a mass extinction, but it’s a real possibility. By stating that potentially exposing the planet to lethal radiation was too great a risk to take for cheap refrigeration Carter saved millions of lives, and possibly the whole planet. You’d think more obituaries would give that a mention.