The year was 1987, and Earth’s shield against the giant thermonuclear reaction in the sky was failing.
September 26, 2022
The year was 1987, and Earth’s shield against the giant thermonuclear reaction in the sky was failing.
Human-made chemicals in aerosol cans and refrigeration were eating up a thin protective layer of atmospheric gas called ozone, and heavy doses of radiation from the sun were leaking through. Scientists warned of a dangerous weak spot over Antarctica—the “ozone hole”—and a dire future.
Unless the world’s 5 billion people took collective action, they said, the hole would grow and new ones would form at higher latitudes and roam the planet. Rates of skin cancer and blindness would increase, and plant and animal life would suffer unpredictable harm.
But that fate was averted. In September 1987, the United States and dozens of key nations signed the Montreal Protocol, a binding agreement to phase out the ozone-depleting substances, particularly chlorofluorocarbons (CFCs) and halons. Three decades later, emissions of the substances have dropped more than 99%, their presence in the atmosphere has halved, and the ozone hole is on track to fully heal by 2070.
“We’ve reached a critical milestone,” said Stephanie Haysmith, a communications officer with the United Nations’ Ozone Secretariat. “We’re on the right path.”
But while the ozone risk has diminished, another global threat has ramped up: human-caused climate change. Experts say that challenge is more complex and more pressing than ozone depletion and drives a need to learn from the Montreal Protocol and repeat its success.
And unlike ozone, humanity is “heading in the wrong direction” on climate, a United Nations report warned this month. In 2021, carbon dioxide, the most problematic greenhouse gas, reached its highest concentration in the atmosphere in at least 3 million years.
Humanity now has less than 30 years left until 2050, when the U.N. warns the world must reach “net zero,” a point of equilibrium where any greenhouse gases emitted into the atmosphere are offset by methods to remove them.
Otherwise, the risks of devastating natural disasters will escalate beyond the already rapid-fire rate they’re striking now, transforming the planet into one less hospitable to human life.
Susan Solomon, an atmospheric chemist at the Massachusetts Institute of Technology, who has studied both ozone loss and climate change, has seen the world tackle one major threat. Now she wonders, what did we learn about how to do it again?
“We avoided a global catastrophe. It’s really quite an achievement.” Solomon said. “How did we do that?”
Lessons learned
Haysmith, whose office at the U.N. administers and enforces the Montreal Protocol worldwide, says there was an early key to its success: Policymakers listened to scientists. Then they acted.
“There was sound, science-based decision-making, followed by solid policy implementation,” Haysmith said.
In the U.S., Congress ratified the Montreal Protocol and in 1990 passed ozone amendments to the Clean Air Act. The Environmental Protection Agency rolled out a number of regulations and phased out CFCs.
Internationally, key countries such as Germany and the United Kingdom took similar measures, said Michael Oppenheimer, a professor of geosciences and international affairs at Princeton University.
