The ozone layer is recovering faster than expected, thanks to global cooperation

Successful bans on chemicals that eat away the ozone layer demonstrate pollution and climate change is a choice

By Matthew Rozsa

Staff Writer

Published June 13, 2024 9:00AM (EDT)

False color image of Antarctic ozone hole, 30 November 1992. NASA photograph.  ((Photo by Universal History Archive/Getty Images))
False color image of Antarctic ozone hole, 30 November 1992. NASA photograph. ((Photo by Universal History Archive/Getty Images))

On September 16, 1987, the international community did something almost unheard of, especially in today's world: It worked together to protect the planet.

"This important milestone demonstrates the benefits of the Protocol for mitigating climate change and stratospheric ozone layer loss."

Ultimately ratified by 198 nations, including every country in the United Nations, the so-called "Montreal Protocol on Substances That Deplete the Ozone Layer" vowed to phase out pollutants that had been eroding Earth's ozone layer.

University of California, Irvine chemists Frank Sherwood Rowland and Mario Molina had proved in the 1970s that a widely-used industrial chemical known as chlorofluorocarbons (CFCs) damaged the environment. (The pair of scientists won the 1995 Nobel Prize for Chemistry for their discovery.) Specifically, they learned when the popular solvent/refrigerant/propellant was released into the atmosphere, it degraded from ultraviolet radiation and therefore released chlorine atoms. Those chlorine atoms in turn broke down large amounts of ozone (O3) in the stratosphere, which had already punched a hole over Antarctica.

Without an adequate ozone layer, life cannot sustain itself on Earth. For that reason — and despite protests from businesses that profited from manufacturing and using CFCs — the international community prioritized preserving this part of the atmosphere. By January 1, 1989, the Montreal Protocol was in full effect... and a recent study in the journal Nature Climate Change reveals it atmospheric levels of ozone depleting chemicals have dropped for first time ever.

Not only does this mean the Montreal Protocol succeeded, it indicates that subsequent efforts to keep it updated also achieved their goals — and it occurred even faster than scientists expected.

While CFCs were officially banned in 2010, a substitute chemical that is also very damaging to the ozone became a common replacement — hydrochlorofluorocarbons (HCFCs). HCFCs are still in the process of being phased out, so it is encouraging to find that HCFC levels as well as CFC levels are dropping in the atmosphere.

Dr. Luke Western, Marie Curie Research Fellow at the University's School of Chemistry, said in a statement that, "the results are very encouraging. They underscore the great importance of establishing and sticking to international protocols. Without the Montreal Protocol, this success would not have been possible, so it's a resounding endorsement of multilateral commitments to combat stratospheric ozone depletion, with additional benefits in tackling human-induced climate change."

“This is a remarkable success story that shows how global policies are protecting the planet,” Veerabhadran Ramanathan, a climate scientist at the University of California at San Diego and Cornell University who was not involved in the study, told The Washington Post.

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"The observed reduction in HCFC abundance is sooner than anticipated and may move forward this date for recovery when considered in future projections."

It is all the more remarkable because it shows that humans can bring the planet back to pre-pollution norms. The abundance of HCFCs in the atmosphere is expected to return to 1980 levels by 2080, and the world overall has curbed 98 percent of the ozone-depleting substances being produced in 1990. Just as importantly, the scientists found encouraging signs regarding the globally averaged chlorine content of ozone-depleting substances (ODS) in the troposphere, a figure known as EECI.

"Our latest observations show that the total radiative forcing [a measure of the change in energy balance as a result of a change in a forcing agent like greenhouse gases] and EECl from HCFCs has fallen for the first time," write the authors. "This demonstrates the success of the controls of the Montreal Protocol in mitigating loss of stratospheric ozone and its additional benefits to the climate. In the absence of future increases in ODS production, it was anticipated that Antarctic ozone recovery will occur later this century."

Forget about meeting expectations; the authors point out that we may actually be surpassing them.

As they added, "The observed reduction in HCFC abundance is sooner than anticipated and may move forward this date for recovery when considered in future projections." But to get there will require cooperation, as they note: "Adherence to the Kigali Amendment, Paris Agreement and Global Cooling Pledge should ensure that, in time, the radiative impact of HFCs will follow a similar decline to that observed for HCFCs."

This is not the only occasion when world leaders have successfully worked together. After ecologist Gene Likens discovered acid rain in the 1960s, scientists and social activists joined forces to support necessary environmental regulations. Acid rain, which is defined as rain with a pH between 4.2 and 4.4, can damage property and cause serious health problems.

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During the mid-20th Century, acid rain became prevalent throughout North America as electricity generation and car use became increasingly common; the processes behind both of those technological phenomena emitted sulfur dioxide (SO2) and nitrogen oxides (NOx), which stayed in the atmosphere and joined with precipitation. Fortunately for humanity, experts worked closely with political leaders to amend the Clean Air Act in 1990, with Republican President George H. W. Bush signing into law measures that managed to significantly reduce acid rain in the United States.

Similarly, the international community worked together to ban hydrogen bomb tests after Democratic presidential candidate Adlai Stevenson drew attention to the problem during the 1956 election. Declaring in a speech to the American Legion that there can be no "real peace while more than half of our federal budget goes into an armaments race . . . and the earth's atmosphere is contaminated from week to week by exploding hydrogen bombs," Stevenson was initially condemned by everyone from President Dwight Eisenhower and Atomic Energy Commission chair Lewis Strauss to ordinary scientists.

Yet as evidence piled up that hydrogen bomb tests leave dangerous amounts of radioactive materials in the environment, American leaders joined with their counterparts in the Soviet Union to restrict testing. In the end, Eisenhower and Soviet leader Nikita Khrushchev agreed to a moratorium on nuclear testing and the beginning of a test ban treaty that was later signed into law (in 1963) by President John F. Kennedy.

All of this underscores that the planet we live on — increasingly choked by pollution and emissions from burning fossil fuels — is a choice. Success stories in climate change and the so-called Anthropocene are seemingly rare these days, but they don't have to be.

By Matthew Rozsa

Matthew Rozsa is a staff writer at Salon. He received a Master's Degree in History from Rutgers-Newark in 2012 and was awarded a science journalism fellowship from the Metcalf Institute in 2022.

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Acid Rain Analysis Atmosphere Climate Change Earth Environmentalism Ozone Reporting