They were once abundant, in our hairsprays, bug sprays, and refrigerators. And then scientists figured out these substances ripped a hole in the ozone layer, leading to a 1987 plan to phase them out that over time would be agreed to by every country in the world.
Ozone-depleting substances (ODS) are synthetic chemicals developed in the 1920s and 30s. They became popular in the 1950s when they were used as refrigerants, solvents and propellants.
A study published Tuesday in Nature Climate Change by researchers at Columbia University examines the greenhouse warming effects of ozone-depleting substances and finds that they caused about a third of all global warming from 1955 to 2005, and half of Arctic warming and sea ice loss during that period.
According to the study, HFC-23, known as fluoroform, is a greenhouse gas that has 12,000 times the global warming potential of carbon dioxide does.
Findings, published in Nature Communications show that emissions from India and China have spiked since 2014 despite pledges by both countries to get emissions down to zero. HFC-23 emissions reached a new peak in 2018. In short, this is very bad news.
On a molecule-by-molecule basis, halogenated organic compounds trap much more heat in the atmosphere than most other known compounds. For example dichlorodifluoromethane (CFC-12) has a global warming potential almost 11,000 times that of carbon dioxide. This means that, although ODS might exist in much smaller atmospheric concentrations than other greenhouse gases, their impact can be just as significant.
Then there’s also the problem of CFCs still being used despite global crackdowns. For example, China is struggling to tamp down on illegal CFC production. In addition, we’ve just begun to tackle hydrofluorocarbons (HFCs), which air conditioner and refrigerator manufacturers turned to when they were blocked from CFCs, on a global scale. HFCs are less harmful for the ozone than CFCs, but like their loathed counterpart, they’re more powerful than carbon dioxide when it comes to trapping heat.
The Montreal Protocol was ratified in 1989 in response the worsening ozone hole. The purpose was to phase out these chemicals, and it has largely worked outside a hiccup or two. That means the ozone hole is likely to heal this century. The new research indicatse that the phaseout might also helped prevent further extreme warming in the Arctic, though some of the replacement refrigerants are pretty powerful greenhouse gases, too. Which, you know, maybe we should stop emitting those, too.