In September 1987, one of the most successful agreements to date regarding the preservation of the environment was signed: the Montreal Protocol, aimed at taking measures to protect the ozone layer, and in which the signatory countries undertook to control the release into the environment of substances such as CFCs.
Thanks to this historic agreement, it is estimated that, on average, the global ozone layer may have returned to levels prior to the 1980s by the middle of this century. However, recent studies show that, despite the resounding success derived from limiting the emissions of harmful compounds, there are still some issues to be resolved.
One of them is the mutual interaction that occurs between two phenomena: the weakening of the ozone layer and climate change . The latter, for example, appears to affect the Brewer-Dobson circulation, an atmospheric circulation model that explains how CFCs end up in polar latitudes.
Now, a paper published in the journal Nature Sustainability shows that the increase in solar radiation that penetrates through the damaged ozone layer is interacting with the changing climate , and that the consequences are spreading through the natural systems of the Earth, affecting everything from climate to health to the abundance of marine mammals like seals and penguins. The article has been written by scientists who are members of the Environmental Effects Assessment Panel of the United Nations Environment Program, in charge of informing the parties to the Montreal Protocol.
“We have observed that changes in ozone have also modified the patterns of temperature and precipitation in the southern hemisphere, and that is affecting the distribution of algae in the ocean, which in turn determines the movements of the fish, and this it has consequences on the distribution pattern of walruses and seals … in short, we are seeing many changes in the food web “, explained Kevin Rose, a researcher at the Rensselaer Polytechnic Institute (New York, USA), one of the study co-authors .
Effect of the weakening of the ozone layer on the climate
The report points to the southern hemisphere, where the hole in the ozone layer over Antarctica has pushed the Antarctic oscillation – a belt of low-pressure winds that surrounds Antarctica and moves from north to south – further south than It has never been in the last thousand years. This movement of the Antarctic oscillation, in turn, contributes directly to climate change in the southern hemisphere. As climate zones have shifted south, rainfall patterns, sea surface temperatures, and ocean currents in large areas of the southern hemisphere have also changed, affecting terrestrial and aquatic ecosystems. The effects can be seen in Australia, New Zealand, Antarctica, South America, Africa, and the Southern Ocean.
Scientists also point to other more subtle interactions between climate change and the ozone layer. For example, higher concentrations of carbon dioxide have acidified the oceans, and this has resulted in a reduction in the thickness of calcified shells, making shellfish more vulnerable to UV radiation. These are effects that also affect human health: temperatures are increasingly higher, so we wear lighter clothing, which in turn makes us more unprotected against solar radiation.
Effect of climate change on the ozone layer
There is increasing evidence that climate change may be affecting the ozone layer and how rapidly it is recovering after the implementation of the Montreal Protocol.
“Greenhouse gas emissions trap more heat in the lower layers of the atmosphere, which leads to a cooling of the upper layers. Because ozone is depleted at lower temperatures, it appears that this cooling in the upper part of the atmosphere is slowing the recovery of the ozone layer, “explained Rose.
The Environmental Effects Assessment Panel is one of three scientific groups monitoring the Montreal Protocol, focusing in particular on the effects of UV radiation, climate change and the depletion of the ozone layer. 39 researchers participated in the writing of this scientific review, entitled ” Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future.”
