By Cristian Martinez-Villalobos, academic from the Adolfo Ibáñez University Faculty of Engineering and Sciences and Data Observatory researcher
On September 16 we celebrate the World Day for the Preservation of the Ozone Layer. Ozone is a gas present in the stratosphere —the atmospheric layer between 15 and 40 km high— that is essential for human life as we know it. Despite existing in very low concentration (less than 10 molecules of stratospheric air in a million are ozone) it can absorb almost 100% of solar ultraviolet radiation of types B and C.
This type of radiation can increase the risk of skin cancersthe cataract development which can end in blindness, and suppress the immune system. It can also affect the plant growthand the plankton concentrations, considered the base of the marine food chain. The fact that this ozone layer exists allows us to sunbathe, and in most cases the greatest adverse effect is simply a bad tan.
The thickness of the ozone layer varies due to natural and human-caused effects. Naturally the northern hemisphere enjoys a higher concentration, and the minimum typically occurs over Antarctica during October. Surrounding regions such as the extreme south of Chile may be subject to greater risk, especially in years when the concentration decreases below normal.
In 1985, a large “hole” was discovered in the ozone layer over Antarctica. Since then, concentrations up to 70% lower than pre-1980 levels have been measured. Due to the serious consequences that the depletion of the ozone layer can have, this led to swift action, first to determine the causes, and second to slow down and eventually stop the growth of this hole. On the first front, it was quickly determined that the main culprit was the sustained emission since the 1930s of artificial compounds called chlorofluorocarbons or CFCs.
These compounds were used in the refrigeration industry and as a solvent. On the second front, the international community decided to act quickly and find a solution to the problem. Around September 16, 1987, just two years after the observational discovery of the hole in the ozone layer, the Montreal Protocol. This protocol, ratified by 196 countries, entered into force in 1989 and established a total ban on various types of CFCs by 1996. As a consequence of it, the hole in the ozone layer has stopped growing, and has even recovered slightly. It is expected to enter 2050 and 2070 stratospheric ozone concentration recovers to pre-1980 levels.
In recent decades, climate change has replaced the hole in the ozone layer as the main environmental problem of our time..
The positive international response to deal with the hole in the ozone layer contrasts with a response that is perceived as less organized, with a lower level of international agreement and, so far, with worse results in dealing with climate change. While there is almost unanimous consensus among the scientific community on the role of humans in climate change, the consensus is much weaker at the political and decision-making levels.
Why this difference in response? To begin with, the hole in the ozone layer is a more limited problem with a relatively easy solution to implement —CFCs were quickly replaced by variants that are much less harmful to ozone (although they are harmful to climate change).
Also the prospect of increases in skin cancers provides a concrete threat that helped align public opinion on this topic. On the other side, climate change is a problem with many facets, with a more complex solution to implement —it involves a significant and costly change in the energy sources that feed the world economy— and where an important part of the industry has opposed , even in some cases applying questionable tactics such as denial of the problem.
Despite the differences mentioned, how the international community collaborated to deal with the problem of the hole in the ozone layer gives us perspective and hope that the world can unite to face climate change.
Partially inspired by the success of the Montreal Protocol, a United Nations Climate Change Convention was established in 1992, the Kyoto Protocol in 1997, and the Paris Agreement in 2015. These agreements are intended to limit greenhouse gas emissions, especially from developed countries, with the aim of keeping global temperature rise below pre-industrial levels.
How effective have these agreements been? In the short term, global temperatures and greenhouse gas emissions continue to rise: the concentration of carbon dioxide, the most important greenhouse gas, is the highest in the last 4 million years. Despite this, there are lights of hope.
According to the latest report by the Intergovernmental Group of Experts on Climate Change, in the last decade a growing number of countries, 24 in total and most of them developed, have managed to lower their greenhouse emissions, still maintaining economic growth. Will the rest of the countries join this trajectory? Will the fight against climate change follow the successful steps of the fight against the hole in the ozone layer? Only the future knows.