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SOURCE: Inside Climate News

DATE: March 17, 2020

SNIP: Starting decades ago, international governments phased out a class of chemical refrigerants that harmed the ozone layer and fueled global warming. Now, a new study indicates that the remaining volume of these chemicals, and the emissions they continue to release into the atmosphere, is far larger than previously thought.

The findings point to a lost opportunity to cut greenhouse gas emissions on a par with the annual emissions from all passenger vehicles in the United States, but also highlight a low-cost pathway to curb future warming, researchers say.

The study, published Tuesday in Nature Communications, looks at “banked” volumes of three leading chlorofluorocarbon (CFC) chemicals whose production is banned but remain in use today in older refrigeration and cooling systems and in foam insulation. CFCs were phased out of production in developed countries by 1996, and in developing countries by 2010, under the Montreal Protocol because of the leading role they played in creating the so-called “ozone hole” in the atmosphere.

Emissions from these remaining CFC sources were equivalent to 25 billion metric tons of carbon dioxide from 2000 to 2020, the study concludes. Averaged over 20 years, that equals the emissions of 270 million automobiles per year according to the EPA’s greenhouse gas equivalency calculator, more than all registered U.S. passenger vehicles.

“If we don’t deal with these banks, they are going to be emitted and contribute to delaying ozone hole recovery and contribute to future warming,” Megan Jeramaz Lickley, a researcher at Massachusetts Institute of Technology’s Department of Earth, Atmospheric, and Planetary Sciences and lead author of the study said.