By Chris Buckley and Henry Fountain © The New York Times Co.
Emissions from China of a banned gas that harms Earth’s ozone layer have sharply declined after increasing for several years, two teams of scientists said Wednesday, a sign that the Beijing government had made good on vows to crack down on illegal production of the industrial chemical.
The findings ease concerns that increased emissions of the gas, CFC-11, would slow progress in the decades-long environmental struggle to repair the ozone layer, which filters ultraviolet radiation from the sun that can cause skin cancer and damage crops.
“We see a huge decline both in global emission rates and what’s coming from eastern China,” said Stephen Montzka, a research chemist with the National Oceanic and Atmospheric Administration and lead author of one of the studies. Work by Montzka and others three years ago first revealed the illegal emissions.
Matthew Rigby, an atmospheric chemist at the University of Bristol in England and an author of the second study, said that if emissions had not declined, “We could be seeing a delay in ozone recovery of years.” As of now, full recovery is still expected by the middle of the century.
Chinese government officials did not immediately respond to requests for comment.
Chemical traders in Shandong, a heavily industrialized province in eastern China where CFC-11 was widely used for making insulating foams, said trade in the banned gas had largely dried up.
CFC-11 was outlawed a decade ago under the Montreal Protocol, the treaty established in the 1980s, when research revealed its effects on atmospheric ozone.
Meg Seki, acting executive secretary of the Ozone Secretariat, the United Nations body that administers the treaty, said the organization was pleased to see that emissions had dropped and that the effect on the ozone layer was likely to be limited. “It is important, however, to prevent such unexpected emissions in the future through continued, high-standard monitoring by the scientific community,” she said.
The new papers, which were published in the journal Nature, do not account for the entire global increase in CFC-11 emissions that had occurred since 2013. The gas may still be being produced or used in other countries or in other parts of China, but the researchers said there are not enough air-sampling stations worldwide to know for certain.