A three-decade-old international treaty to phase out chemicals that deplete the ozone layer is paying off. After scientists discovered a hole growing over Antarctica in 1985, they have been working to find a solution before the hole gets any bigger and that solution was the Montreal Protocol. This year, the hole spans an area slightly smaller than the entire North American continent, about nine-million square miles. This hole has caused the planet to warm up by one degree Celsius within the last century and global temperatures are expected to increase another degree or more over the next century.

The return of the ozone layer

The ozone layer is a 31-mile-wide buffer that occurs naturally above the troposphere and protects the Earth against ultraviolet-B radiation from the sun. Without this layer, life on our planet would not exist.

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The Montreal Protocol should have the ozone in the northern hemisphere returned to healthy levels in the 2030s, southern hemisphere in the 2050s, and polar regions in the 2060s. As long as countries around the globe still follow the treaty.

The bad news

However, it’s not all good news. There are certain ozone-depleting substances like chlorofluorocarbon-11 (CFC-11) that are decreasing from the atmosphere slower than expected. There has been an increase in these emissions over eastern Asia since 2012 according to two independent networks.


CFC-11 emissions are banned under the Montreal Protocol. If they continue in our atmosphere, they’ll cause more damage for generations to come.

A hopeful future

There’s still hope. The Kigali Amendment addresses chemicals used to replace those banned by the Montreal Protocol and will take effect in January 2019. With this amendment in place, we could avoid global surface temperature increases between 0.2 to 0.4 degrees Celsius.

Joshua Brown/University of Vermont

This estimate is according to the 2018 Scientific Assessment of Ozone Depletion released by the World Meteorological Organization and the United Nations Environment Programme. The benefits of eliminating these substances would be substantial for the future of our planet.