Posted at 12:00 p.m
by-products
“Atmospheric concentrations of five theoretically banned chlorofluorocarbons (CFCs) increased between 2010 and 2020,” said Luke Western of the University of Bristol in the UK during a news conference. “In two cases we don’t understand what’s going on. It’s worrying. »
PHOTO FROM BRISTOL UNIVERSITY WEBSITE
Luke Western, University of Bristol
The three explainable phenomena described in the study, published Monday in the journal Nature Geoscience — namely increases in levels of CFC-113a, CFC-114a and CFC-115 — are related to chemical production. “There is no reason to have so many emissions from these three CFCs,” says another co-author, Stefan Reimann, from the Federal Laboratories in Dübendorf. “It’s a problem, but we can fix it. »
Even more worrisome, no known industrial process can explain such high concentrations for the other two CFCs that are increasing in concentration. “So they must be unexpected by-products of certain reactions,” Western speculates.
A hole in Antarctica
The ozone hole is created in Antarctica because it needs cold for the chemical reaction with the CFCs responsible for the destruction of the ozone molecules to take place. It peaks in September or October each year. The ozone layer protects the earth from the sun’s ultraviolet rays, which significantly increase the risk of cancer. Since CFCs take a century to break down, the ozone hole, which has been shrinking since 2010, will not disappear until 2080. This hole was discovered in 1989 and the production of most CFCs was banned from 2009.
Heat
According to Mr. Western, this increase in the concentration of five CFCs has not currently affected the absorption of the hole in the ozone layer. “But who knows what’s in store for us if we don’t address the issue? On the other hand, the five CFCs identified in the Nature Geoscience study contribute about 1% to global warming because they are particularly potent greenhouse gases.
Kigali
CFC’s successors as refrigerants, hydrofluorocarbons (HFCs), are harmless to the ozone layer but have almost the same global warming potential. For this reason, in 2016 the Kigali Convention (ratified by Canada in 2017 and the United States in 2022) envisaged their elimination and their replacement with other molecules, probably hydrofluoroolefins (HFO).
“The question now is whether there will be any by-products of HFO production that are CFCs,” Western said. Parisa Ariya, a chemist at McGill University, says HFC use is declining in the West, particularly in Canada. “But the ozone layer is complex and so is its interaction with the climate,” she warns.
PHOTO FROM MCGILL UNIVERSITY WEBSITE
Parisa Ariya from McGill University
University of Montreal colleague Patrick Hayes is also concerned about seeing a new trap in healing the ozone layer. “It’s quite surprising. After the controversy about illegal CFC emissions in China, another problem arises here. when will this stop »
The Chinese riddle
Illegal production of CFC-11 in China was discovered in 2018 and factories were shut down. But that remains a sensitive issue. “Despite our collaboration with Chinese researchers, we do not have access to Chinese data on CFC emissions,” says Western. His colleague Stefan Reimann reports that measuring stations in South Korea can cover part of China. “Let’s assume there is room for improvement in data sharing. »
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100,000 tons annual world production of chlorofluorocarbons, early 1990s
Source: nature
47 Number of countries that have signed the Montreal Protocol but not the Kigali Convention
Source: un