The Ozone-Defending Montreal Protocol Is a Rare Gift That Keeps Giving

The Montreal Protocol, already hailed by Kofi Anan as “perhaps the single most successful international agreement to date,” can add another feather to its cap. In addition to slowing the growth, and then shrinking, of the hole in the ozone layer, the researchers have used computer models to demonstrate that without the reduction of CFCs, the environmental changes projected for the next decade—already expected to be really bad—would be twice as severe.

It certainly wasn't part of the reason for ratifying the Montreal Protocol, which was aimed specifically at reducing the hole in the ozone layer over Antarctica, but it's another positive result–collateral benefit, if you will. "We dodged a bullet we did not know had been fired," said Richard Seager, a scientist at Columbia University's Lamont-Doherty Earth Observatory who coauthored the study.

The researchers ran a computer model that projected a world where the Montreal Protocol wasn’t signed and CFC use continued unabated through the ‘90s to the present. They found that global rainfall patterns—which are changing severely enough in reality from rising carbon dioxide levels–would have been disrupted twice as badly. As the ozone layer was depleted:

The jet stream in the mid-latitudes would have shifted toward the poles, expanding the subtropical dry zones and shifting the mid-latitude rain belts poleward. The warming due to added CFCs in the air would have also intensified cycles of evaporation and precipitation, causing the wet climates of the deep tropics and mid to high latitudes to get wetter, and the subtropical dry climates to get drier.

Due to a childhood subscription to Ranger Rick, I was exposed to the impending environmental catastrophes at a young age. Global warming was a concern—and a bummer for a kid who loved to sled—but even worse was the growing hole in the ozone layer. Thanks to cans of hairspray–or specifically the chlorofluorocarbons used in spray cans at the time–soon the only way to go outside without getting sunburns and eventually skin cancer would be in a HAZMAT suit.

But then a magical, unthinkable thing happened. Consumers, nations, and the UN agreed that having an ozone layer is a worthwhile thing. Through self-imposed boycotts, national laws and almost 200 nations ratifying the Montreal Protocol since it was first agreed upon in 1987, the use of nearly 100 damaging chemicals was reduced by nearly 100 percent. This latest study, published in the Journal of Climate, shows that the legislation to repair the ozone layer has had a positive effect on the global climate as well, even if CFCs weren't well enough understood at the time for hydrological disruptions to be a reason for ratifying it.

CFCs take a long time to dissipate, so the effects of decades of CFC use are expected to linger until the middle of the century. And the chemicals that replaced CFCs weren’t without their drawbacks.

CFCs were often replaced by hydrofluorocarbons and hydrochlorofluorocarbons, which don’t deplete the ozone layer, but are considered “super greenhouse gases.” HFCs are the fastest growing climate warmer in the United States and elsewhere, growing globally at 10 to 15 percent per year. But compared with an all CFC world, HFCs and HCFCs were the lesser evil. CFCs can be thousands of times more potent than CO2, and a 2007 study found that CFCs would’ve generated the warming equivalent of 11 billion tons of carbon dioxide on average every year–almost an extra 30 percent on the 32 billion tons humans generated in 2010. Without the Montreal Protocol the equivalent of over 220 billion tons of carbon dioxide would've been added to the atmosphere over those 20 years.

The Montreal Protocol was already considered one of the most successful environmental treaties of all time, a rare instance of the problem being identified and attacked both by the public and legislatively in just 17 years. As we barrel toward the climate-change point of no return, the Montreal Protocol is now a two-prong symbol of hope: maybe legislation can have an effect, even in the face of industry opposition, and also, maybe one of the laws already on the books is surprising us by preventing environmental disaster.