Atmospheric concentrations of a second class of energy-depleting chemicals ozone layer They peaked in 2021 and are now starting to decline.
These substances, hydrochlorofluorocarbons (HCFCs), have been used as first-generation alternatives to the more harmful chlorofluorocarbons or CFCs, which were responsible for creating the spring hole in the ozone layer over Antarctica.
HCFCs also deplete ozone and trap heat in the air. atmospherebut to a lesser extent than the CFCs they replaced in the manufacture of refrigerants, foaming agents and solvents.
In September 2007, the parties to the Montreal Protocol decided to accelerate their program to phase out the production of HCFCs for use in applications that account for the majority of releases to the atmosphere. Developed countries have completely phased out HCFCs by 2020. Developing countries have agreed to begin their phase-out process in 2013 and establish a complete phase-out of HCFCs by 2030.
Lead author Luke Western, a research fellow at the University of Bristol’s School of Chemistry, said the results underline the value of establishing and following international agreements such as the Montreal Protocol on substances that deplete the ozone layer.
“Without the Montreal Protocol, this success would not have been possible, making it a resounding endorsement of multilateral commitments to combat the impacts of human-induced climate change,” Western, who began this work while he was researcher at NOAA’s Global Monitoring Laboratory. The research is published in Nature Climate Change.
Five years ahead of schedule
Using high-precision measurements of air samples provided by NOAA’s Global Greenhouse Gas Reference Network and the Advanced Global Atmospheric Gas Experiment obtained at their globally distributed atmospheric observatories, the researchers were able to determine how much the depletion impact ozone layer and the heat-trapping impact of HCFCs had peaked five years earlier than expected.
Adopted in 1987, the Montreal Protocol is a multilateral environmental agreement that introduced controls on the production of ozone-depleting substances such as CFCs.
CFCs were once widely used in the manufacturing of hundreds of products, including aerosols, cooling devices, blowing agents for foams and packaging, and solvents.
Scientists hope that compliance with the controls agreed upon by the parties to the Montreal Protocol will restore the stratospheric ozone layer by 2065, which will prevent 443 million cases of skin cancerapproximately 2.3 million skin cancer deaths and more than 63 million cases of cataracts in the United States alone, with even greater benefits worldwide.
HCFC concentrations in the atmosphere are small (measured in parts per trillion) and their contribution to warming peaked at about 1% of the warming of the sum of all long-lived greenhouse gases and 2.8 % of CO2 warming.
Once HCFCs leak into the atmosphere, they are much more efficient than an equal amount of CO2 at trapping heat in Earth’s atmosphere that would otherwise escape into space.
The warming produced by the release of the most widely used HCFCs over 100 years is almost 2,000 times greater than that produced by an equivalent amount of CO2.
Source: EUROPA PRESS
