Adopted 35 years ago, the Montreal Protocol remains a groundbreaking environmental agreement, credited with saving millions from skin cancer and playing a major role in protecting Earth’s climate. Officially titled the “Montreal Protocol on Substances That Deplete the Ozone Layer,” this crucial U.N. treaty bans the release of harmful chemicals like chlorofluorocarbons (CFCs), which damage the ozone layer.
Here are four key facts about ozone and the treaty that safeguards it.
1. The Montreal Protocol was written to address ozone depletion caused by industrial chemicals.
In the 1970s, scientists (including several experts from NOAA) discovered that an important function of the stratosphere performed by ozone was impaired by persistent, industrial chemicals known as chlorofluorocarbons (CFCs). These chemicals led to the destruction of ozone molecules and depleted the layer that protects all life on Earth. One key concern was the large “hole” which was opening in the ozone layer each year over Antarctica.
Stratospheric ozone, which is found about 7-25 miles above the Earth, protects life on the Earth’s surface from the harmful effects of ultraviolet radiation, including skin cancer and weakened immune systems in humans. It also enables healthy ecosystems and productive agriculture.
Atmospheric scientists identified the actions that humans were taking to cause the stratospheric ozone depletion. Chlorine and bromine, released by the breakdown of CFCs, were particularly problematic. The 1987 Montreal Protocol phased out production and use of these and other substances that deplete ozone. These bans have had a significant, positive impact on the ozone layer.
2. The loss of stratospheric ozone changed weather in more than half the planet.
In addition to allowing more ultraviolet radiation to penetrate to the surface, the ozone hole forming over Antarctica each year created many wide-ranging climate impacts on the Southern Hemisphere. By the 1980s, scientists noted that jet streams were changing. As a result, Australia got drier, and the rain increased in parts of Uruguay, Brazil, Paraguay, and Argentina.
The changing wind patterns that caused these effects paused around the year 2000, approximately when the Montreal Protocol began to take effect. In 2020, researchers from NOAA’s Chemical Sciences Laboratory documented that declining atmospheric concentrations of ozone-depleting chemicals were responsible.
3. The Montreal Protocol is the only U.N. treaty ratified by every country on Earth.
One hundred and ninety-seven U.N. member states adopted the Montreal Protocol, making it the only U.N. treaty ratified by every country on the planet. President Ronald Reagan, when signing the document, called it a “model of cooperation” and pledged that the U.S. would give the “highest priority to analyzing and assessing the latest research findings.”
Numerous amendments over the years since it was first written have helped to incorporate new research findings on ozone. Those amendments have also helped to address new challenges that have arisen.
CFCs deplete the ozone layer, but scientists have also learned that they are also potent greenhouse gases, which lead to the warming of the Earth’s surface climate. Controlling CFCs helped to reduce greenhouse gas emissions around the world — an important action toward reversing the trend of climate change.
A new problem emerged, however, when some of the ozone-saving substitutions made for the CFCs were found to be problematic in other ways. Hydrofluorocarbons (HFCs) cause considerably less damage to the ozone layer compared to CFCs because they lack chlorine and bromine, but are powerful greenhouse gases. In October 2016, the Kigali Amendment was adopted to phase down future global production and consumption of HFCs, marking the first time the Montreal Protocol adopted regulations solely for the protection of climate. Its global implementation should prevent as much as half a degree Celsius of warming by the end of the century.
4. Future innovations may need to be monitored for their impact on ozone.
In the coming years, the Montreal Protocol may need to address several new atmospheric challenges.
NOAA’s Office of Atmospheric Research found that space traffic, which is projected to increase in the future, could boost emissions of soot directly into the stratosphere, which could deplete the ozone layer in some seasons.
“We need to learn more about the potential impact of hydrocarbon-burning engines on the stratosphere and on the climate at the surface of the Earth,” said Christopher Maloney, a research scientist from the Cooperative Institute for Research in Environmental Sciences working in NOAA’s Chemical Sciences Laboratory. “With further research, we should be able to better understand the relative impacts of different rocket types on climate and ozone.”
At the same time, a team of international experts has noted that several space-borne satellites providing ozone-related atmospheric measurements are due to be retired within a few years. Without replacements of these instruments, it could be difficult to monitor and explain changes in the stratospheric ozone layer in the future.
NOAA staff work closely with scientists worldwide to monitor ozone depletion and actively participate in conferences on the Montreal Protocol’s terms and amendments. For the tenth scientific assessment of the treaty, about 230 scientists from 30 countries contributed their expertise. They concluded that Earth’s protective ozone layer is on a path to recovery, expected to reach pre-ozone-hole levels by approximately 2066 over Antarctica, 2045 over the Arctic, and 2040 for most other regions.
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7 Comments
“…, credited with saving millions from skin cancer …”
Interestingly, melanomas are commonly found on the parts of the body that rarely, if ever, experience sunburns.
“These bans have had a significant, positive impact on the ozone layer.”
If one looks at the graphs and tables provided at https://ozonewatch.gsfc.nasa.gov/ , it is evident that the Antarctic ozone levels and, particularly the area of the annual ‘hole,’ are fairly constant since about 1990, with the notable exceptions of 2002 and 2019 when warm weather caused disruptions in the annual Antarctic Circumpolar Vortex. It appears that Antarctic temperatures play a more “significant” role than the stratospheric halides. Perhaps the apparent decline in the size of the ozone hole is a spurious correlation, or perhaps it is related to a warming climate. Has anyone considered this alternative hypothesis?
Why is it that the anomalously high ozone levels (shown in blue) outside the circumpolar vortex, during the period of the ‘hole,’ are never mentioned. Indeed, the relatively new ozone-concentration color rendition used for this article suppresses that fact — One’s eye is drawn to the bright-Red, Orange, Yellow bullseye. If one uses the common ‘rainbow’ color table, sometimes it results in less than optimal information transmission because something important is happening where the color is changing slowly. However, it is evident that the color table used here (notably, green is missing, as are indigo and violet with intermediate values represented with a low-saturation grey) is a custom table. That means, someone made the conscious decision to downplay the importance of the elevated ozone outside the vortex. It should be noted that the Antarctic ozone is largely the result of the Brewer-Dobson circulation bringing ozone to the poles, and the ozone is actually more abundant at the Antarctic Circle than it is at the origin in the stratospheric tropics.
I’m a great believer in science, which is why I’m usually critical of poor research. However, this is yet another example of data manipulation to force the conclusion desired by politicians.
Note and compare the color rendition of the ozone map shown at https://scitechdaily.com/antarctic-ozone-hole-is-the-smallest-on-record-since-its-discovery/ with the map provided with this article.
This has been a standard used by NASA for years and clearly shows the anomalously high ozone concentration outside the circumpolar vortex.
Something else to note is the asymmetry of the actual so-called ‘hole.’ This is typical. It appears to me that some ozone manages to diffuse across the vortex boundary, replenishing some of the depleted ozone. These are important phenomena that the well-paid ‘professionals’ should be bringing to the attention of the public, not me. Is the taxpayer getting their money’s worth?
“By the 1980s, scientists noted that jet streams were changing.”
That is NOT proof that “the ozone hole forming over Antarctica each year” was responsible. It is at best simply demonstrating a correlation, which may well be spurious — something that is sometimes called anecdotal ‘evidence.’
Both NOAA and NASA need to clean up their act and push back on political influence. They should be free to follow the evidence, wherever it leads, and return to the idea of an objective observer. However, when their funding depends on ‘saving the world,’ that may be difficult to do.
And in another, recent article on this website it’s been said that the ozone layer has repaired on its own. What gives?