“In 1985, atmospheric scientists in Antarctica noticed something troubling. For decades, they’d been measuring the thickness of the ozone layer in the upper atmosphere, the layer of gas that deflects much of the sun’s radiation. Starting in the 1970s, it had started plummeting. By the mid-1980s, they observed that it was on track to be wiped out in the next few decades.
Their discovery was cause for worldwide alarm and unprecedented action. In short order, the international community marshaled its resources — scientific, economic, diplomatic — to mount a campaign to ban the chemical that caused the damage, chlorofluorocarbons (CFCs), and to restore the ozone layer.
Fast-forward to today: The ozone is on the path to recovery, if not fully restored. That progress hasn’t been without setbacks. The ozone hole is shrinking on average, but some years are bad ones — the hole was notably larger in 2020, following a 2019 when it was unusually small. Researchers have also raised suspicions that the rate at which atmospheric CFCs are falling suggests not all signatories to a treaty banning new production of CFCs are abiding by the agreement. And there have been unintended consequences in phasing out CFCs with a different chemical that has hurt our fight against climate change (more on this below).
But the damage we wrought last century has been reversed. Even with the complications and caveats, the world’s response to the ozone crisis should be seen as an instructive, even inspiring, success story — one that can perhaps inform our response to the climate crisis.”