16 September 2020
Thirty-five years ago the world came together in a remarkable act of international cooperation, unanimously agreeing to take decisive action to protect the Earth's ozone layer. Today, on World Ozone Day, we celebrate this extraordinary achievement.
Starting in the 1970s, scientists postulated that chlorine-containing chemicals used as refrigerants, known as chlorofluorocarbons (CFCs), could react and destroy ozone in the stratosphere. It was an alarming proposition—the stratospheric ozone layer is vital for shielding life on this planet from harmful ultraviolet radiation, yet CFC usage was on the rise globally and increasing levels of CFCs were being measured in the atmosphere. In their landmark 1974 paper, Molina and Rowland concluded that these compounds, which are unreactive and stable near the surface, could shed their chlorine atoms under the much higher UV exposure of the stratosphere, and initiate a series of chemical reactions that would destroy ozone.
The existence of an "ozone hole" over Antarctica was first reported in 1985 and was linked to emissions of CFCs. The same year, the world's governments adopted the Vienna Convention for the Protection of the Ozone Layer, setting the stage for the Montreal Protocol of 1987, a landmark treaty that phased out the use of CFCs and put us on the path toward ozone recovery. The Montreal Protocol was the first UN treaty to achieve universal ratification, having been signed by every member country of the United Nations.
Under the Convention's Montreal Protocol, governments, scientists, and industry worked together to eliminate 99% of CFC emissions. Thanks to this concerted effort, the ozone layer is now showing definitive signs of healing and is projected to return to 1980 levels by mid-century.
NOAA CSL has played an important sustained role in advancing the science of ozone depletion and communicating the science to the Montreal Protocol. CSL Director David Fahey is currently a co-chair of the Montreal Protocol Scientific Assessment Panel (SAP), which leads the production of the quadrennial Scientific Assessment of Ozone Depletion report for the Protocol.
In support of the Montreal Protocol, the Kigali Amendment, which came into effect in 2019, will work towards reducing hydrofluorocarbon (HFCs), greenhouse gases with powerful climate warming potential and damaging to the environment. Although this is a critical piece of the climate issue now facing us, much work remains to be done.
There's an invaluable lesson inherent in World Ozone Day that is important to recognize. We humans are a powerful species, more so than we realize. We are powerful in our ability to impact and disrupt our environment, but we are equally powerful in our capacity to make positive change. This is a lesson that is all too easy to forget, especially in a year that has brought many challenges to a society that often can seem more divided than ever. Ozone protection is a success story of what we are capable of when we come together and work towards a common good. It shows that collective decisions and action, guided by science, are the only way to solve major global crises. The UN theme for this year, Ozone for Life, reminds us that not only is ozone crucial for life on Earth, but that we must continue to protect the ozone layer for future generations.