A Proven Treaty, a Cooler Future—and an Arctic Caveat
Source: UNEP Ozone Secretariat
The UN marked the International Day for the Preservation of the Ozone Layer on Wednesday, September 16. The General Assembly set the date to commemorate the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987, the treaty that phased out the synthetic refrigerants—chlorofluorocarbons and halons—responsible for stripping ozone from the stratosphere.
This year the observance doubles as an anniversary. The Kigali Amendment, adopted in 2016, extended the protocol to hydrofluorocarbons (HFCs), potent greenhouse gases that replaced the banned refrigerants in air conditioners and refrigeration systems. Over the past decade the amendment has driven a global phase-down of HFCs and pushed the cooling sector toward more efficient equipment, stronger industrial capacity, and new technology.
Global Action for a Cooler Planet
The 2026 theme is “Global action for a cooler planet,” marking ten years of sustainable cooling under the Kigali Amendment. The UN is running the campaign alongside the slogans “A proven treaty. A cooler future.” and “The Montreal Protocol: decades of climate benefits,” tying ozone protection directly to the climate agenda.
UN Secretary-General António Guterres framed the theme as a matter of survival rather than comfort.
“As temperatures rise and extreme heat becomes more common, access to efficient cooling saves lives. We must meet that need fairly and sustainably,” he said in his message for the day.
Fully implemented, the Kigali Amendment alone could avoid up to 0.5 degrees Celsius of global warming by the end of the century, and twice as much when paired with energy-efficient cooling—a gain Guterres called “essential for health, food security, livelihoods, and climate resilience.”
The World Ozone Day 2026 campaign poster. Source: UNEP Ozone Secretariat
The Arctic Caveat
The warming the treaty is meant to limit may also work against the ozone layer at the top of the world. Alexey Kokorin, a climate expert at the Russian foundation Nature and People, told TASS that global warming is reshaping the conditions under which polar ozone is destroyed.
“Can an ozone hole appear over the Arctic precisely as a result of climate change? In principle, yes, because one of the features of global warming is that the troposphere warms while the stratosphere cools. That means there will be more and more cases, more and more often, when it is very cold up there but sunlight is already present—so a small, very weak ozone hole may form,” Kokorin said.
The mechanism is well documented: ozone loss over the poles requires a stable polar vortex, stratospheric temperatures near minus 80°C, and the polar stratospheric clouds that form in them, followed by returning sunlight to trigger the chemistry. A colder stratosphere makes that combination more likely in the Arctic, where large ozone holes have so far been rare anomalies rather than an annual event as in Antarctica.
Source: UNEP Ozone Secretariat, UN Press, TASS (in Russian)