In 1987, 197 countries signed the Montreal Protocol, an international agreement to stop releasing chemicals that were eating away a hole in our planet's ozone layer. In a rare scientific triumph, the hole in the ozone layer has just about returned to the size it was at the time of the protocol's signing: at its peak size in September, NASA reported that the hole was about 7.6 million square miles wide, the smallest it has been at peak since 1988.
Unfortunately, we may have helped solve one global problem with another, arguably bigger one. Warmer temperatures in the low pressure system that rotates above Antarctica, known as the Antarctic vortex, prevented many stratospheric clouds from forming; it's within these clouds that the first steps that lead to ozone-destroying reactions occur. In other words, at least this year, we could have global warming to thank.
"Weather conditions over Antarctica were a bit weaker and led to warmer temperatures, which slowed down ozone loss," said Paul A. Newman, chief Earth scientist at NASA's Goddard Space Flight Center, to the Washington Post. "It's like hurricanes. Some years there are fewer hurricanes that come onshore...this is a year in which the weather conditions led to better ozone [formation]."
Video Credit: NASA's Goddard Space Flight Center/Kathryn Mersmann
The hole in the ozone layer was first clearly detected in 1984, by British Antarctic Survey scientists monitoring the atmosphere. After the team published their discovery in 1985, it spurred an international effort to reduce ozone-depleting compounds, specifically chlorofluorocarbons (CFCs) that were then commonly used as refrigerants. When the sun's rays hit the chemically active forms of chlorine and bromine that come from these compounds, they produce reactions that destroy ozone.
Given that the ozone layer is primarily responsible for filtering out dangerous ultraviolet radiation from the sun, closing this hole — and preventing new ones from forming — is certainly good news. What's more, the story of how we got here could be informative in addressing climate change as well.
The Role of International Cooperation
Though climate contributed specifically to the reduction in ozone hole size we saw this year, the global reduction in atmospheric levels of CFCs following the Montreal Protocol has been the main reason that the ozone hole has continued shrinking.
Because CFCs hang around in the atmosphere for decades, scientists estimate that it will take until 2070 for the hole to return to the size it was in 1980. However, if this reduction hadn't happened, NASA modelers estimate that by 2020 we would have seen 17% of global ozone destroyed, with holes above both the Arctic and Antarctic; by 2065, global ozone would have been almost entirely depleted.
Ian Rae, honorary professorial fellow at the University of Melbourne, wrote in The Conversation that while no single factor led to the Montreal Protocol's success, the strong leadership and open discussion during negotiation enabled "a genuine exchange of views and the opportunity to take some issues on trust."
Including scientists in the negotiations lent credibility to the discussion; and because the science wasn't concrete at the time, the negotiators developed a highly flexible agreement that could be retooled as the science became clearer.
Durwood Zaelke, founder and president of the Institute for Governance and Sustainable Development, told Motherboard that efforts to address climate change could learn from the Montreal Protocol by breaking it into "more manageable pieces, where you can focus on solving that one piece."
Additionally, while climate deals like the Kyoto and Paris agreements have been voluntary, trade sanctions that allowed signatories to trade only with other signatories — used as a last resort — were a big factor in getting other countries to sign up for the Montreal Protocol.
It's true that CFCs were never as controversial as climate change, and that greenhouse gas emissions come from many more sources than the refrigerants we had to limit to save our planet's ozone. Yet the levels of international cooperation that we saw are worth taking a lesson from — especially given the successes we see now.