How a public health crisis helped reduce climate change.
International treaties on climate change do not come easily. New research shows that the only treaty ever to be ratified by every country on Earth — the Montreal Protocol — had a substantial beneficial impact on climate change. But that was only a collateral effect of a treaty designed to save the ozone layer.
Negotiating an international treaty is difficult. If that treaty only has a meaning if all countries in the world ratify it, it’s almost impossible. Now add an additional requirement of that treaty addressing climate change, and you have something beyond the bounds of possibility.
True, there is the Kyoto Protocol of 1997 and the Paris Agreement of 2015. Neither of them have been adopted unanimously: The Unites States have not ratified the Kyoto Protocol and just announced their withdrawal from the Paris Agreement. Ten countries have not ratified the Paris Agreement to date. In any case, neither of the two treaties are particularly ambitious about tackling climate change.
It is very different if a human health threat needs to be addressed.
The Montreal Protocol, adopted in 1987, is to date the only UN treaty ever that has been ratified by every country on Earth — all 197 UN Member States. It’s about things we were releasing into the atmosphere. Not because we specifically wanted to, but because it just so happened while we were doing something else. Like cooling our drinks in the fridge. During the years leading up to the Montreal Protocol, first scientists, then people, and finally even politicians learned about the averse effects of chlorofluorocarbons on the ozone layer in the stratosphere. And the resulting risk of skin cancer due to unblocked UV radiation.
It only took them a few years to act. All of them. The entire world.
Scientists have been saying for over a century that carbon dioxide warms the Earth; the first study specifically warning of global temperature increase when doubling CO2 was published by Svante Arrhenius in 1896. So it’s about things we are reasing into the atmosphere. Not because we specifically want to, but because it just so happens while we are doing something else. Like driving to work. People have heard about it. Politicians have heard about it. But they don’t do anything.
What’s the difference?
Simple: For ozone, there was a clear threat of serious health impacts. On humans. Now. Ultraviolet radiation would not be blocked by the ozone layer anymore, and skin cancer risks would increase alarmingly. The Montreal Protocol was signed one year after the Chernobyl accident, which made everybody scared of two things: Radiation (check) and cancer (check).
What’s an equally devastating threat on the entire global flora and fauna within fifty years worth against that? Not much. Climate change is not immediate, it’s not a direct threat to humans (storms, floods and heat will kill us, not carbon dioxide), and it is therefore a phantom menace, not an immediate danger.
As it turns out, the Montreal Protocol was a very successful treaty to reduce climate change. By coincidence, not by design.
When the heads of state gathered in Montreal to ban ozone depleting substances, they all knew about the alarming scientific findings of how these chemicals destroy ozone in the upper atmosphere and cause an increase in dangerous ultraviolet radiation. They were scared and they acted. And they saved a lot of people, both present and future.
What few people know is that CFCs are also greenhouse gases, just like carbon dioxide. Thus, by restricting ozone depleting substances, the Montreal Protocol also put restrictions on a particular sort of greenhouse gases.
In our new study (open access), we were able to quantify just how much the Montreal Protocol has done for the climate.
We found that the measures put in place after the Montreal Protocol spared much of the Northern Hemisphere about 1℃ of warming until 2019, and about 2℃ of warming by 2050. Those numbers look familiar? Indeed, without the accidental benefit of that international treaty, the Paris Agreement would be meaningless, as we would be dangerously close to the warming to be avoided at all cost — the Paris Agreement would truly be too late.
Besides the very serious impacts we are talking about here, I think it is worth pointing out an interesting parallel between the science and politics in this context:
In 1987, Politicians set out to fix a potential human health crisis by saving the ozone layer which protects us from deadly ultraviolet radiation. Unknowingly, they saved Earth not once, but twice, as the averted stronger greenhouse gas effect was a collateral effect.
We as a research team set out to study effects of the ozone hole and its future recovery on the position of a zone of very strong winds around the globe, the so-called jet stream. While conducting the numerical experiments, we saw something unexpected: Earth was much warmer in the simulations where the ozone hole was allowed to progress as if no Montreal Protocol ever existed. We didn’t plan to study this, but accidentally found that the Protocol effectively mitigated climate change while we were studying something else.
Clearly, both politics and science sometimes go places nobody could have predicted. I personally find this one of the most beautiful parts of scientific research: You can’t know what you are going to find! It seems that similar things happen in politics. Seems that whatever we do, we’re humans after all.
The scientific article referenced here is openly accessible at https://iopscience.iop.org/article/10.1088/1748-9326/ab4874.
Dr. Martin Jucker is a lecturer in Climate Dynamics at the University of New South Wales in Sydney, Australia. His work concentrates on the physics of the atmosphere, and how various phenomena impact, modify, and define our current climate.
