China’s emissions of a banned gas that harms the earth’s ozone layer have plummeted after increasing several years, two teams of scientists said on Wednesday, a sign that the Beijing government has endorsed promises to curb illegal production of the industrial chemical cage.
The findings alleviate concerns that increased emissions of the gas, CFC-11, will slow progress in the decades-long environmental battle to restore the ozone layer, which filters ultraviolet radiation from the sun that can cause skin cancer and damage tumors.
“We are seeing a tremendous decline in global emissions and coming from eastern China,” said Stephen A. Montzka, a research chemist at the National Oceanic and Atmospheric Administration and lead author of one of the studies. Work of dr. Montzka and others three years ago first brought the illegal release to light.
“There seems to have been significant reactions, possibly due to the fact that we hoisted a flag and said, ‘Hey, something is not happening the way it should,'” Dr. Montzka said.
Matthew Rigby, an atmospheric chemist at the University of Bristol in England and an author of the second study, said that if we did not reduce emissions, ‘we could see a delay in ozone recovery for years’ time. . ‘ From now on, the 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 is widely used in the manufacture of insulating foam, said trade in the banned gas had largely dried up. “It has not completely disappeared yet, but much rarer than before,” Gao Shang, a chemical trader in Shandong, said in a telephone interview.
CFC-11 was banned a decade ago under the Montreal Protocol, the treaty established in the 1980s, when research revealed its effects on atmospheric ozone, as well as the effects of similar chemicals commonly used.
The revelation in a 2018 study of rogue emissions from China that began five years earlier was a shock to scientists, policymakers, environmentalists and others monitoring the protocol, which is largely regarded as the most effective environmental treaty in history.
Meg Seki, acting executive secretary of the Ozone Secretariat, the body of the United Nations that administers the treaty, said the organization is pleased to see that emissions have dropped and that the impact on the ozone layer is likely to be limited. “However, it is important to prevent such unexpected emissions in the future through continued high standard monitoring by the scientific community,” she said in a statement.
The 2018 research did not determine the source of most emissions than it was from East Asia. But investigations by the Environmental Investigation Agency, an independent law firm in Washington, DC and The New York Times, have found evidence that the gas is still being produced and used in eastern China, particularly Shandong.
An atmospheric analysis led by dr. Rigby in 2019 found that Shandong, as well as a neighboring province, Hebei, were important resources.
When the Chinese environmental authorities were first confronted with the evidence, they had doubts about the findings, suggesting that there may be other, unexplained sources of the chemical, or that insulating foam manufacturers would not have as much CFC-11. do not use.
At the same time, the Chinese Ministry of Ecology and Environmental Protection has promised ‘zero tolerance’ for businesses that illegally manufacture or use CFC-11.
Policy announcements, industry reports and court rulings indicate that the Chinese government has cracked down on illegal trade, even though it still denies there was ever a serious problem. Last year, the government announced a conviction of a businessman, Qi Erming, as the first case in China of a criminal prosecution for the illegal trade in ozone-depleting chemicals.
In addition to prosecutions, the government has tightened the rules and monitoring of the chemical and foam production industry and promised to create a comprehensive data system to track the movement of chemicals that can be used to make CFC-11.
There are legal gases that can replace CFC-11 in foam production. Mr. Gao, the chemical trader in Shandong, said that his company specializes in one of them.
The availability of substitutes could potentially help China’s efforts to reduce CFC-11 emissions. Zhu Xiuli, a sales manager at another company in Shandong that sells foam agents, said customers had earlier asked if they had CFC-11. But ‘over the past few years, there have been fewer and fewer inquiries,’ she said.
CFC-11 has also been used in refrigeration equipment. As the equipment ages and as foam with CFC-11 decreases over time, the gas will be released slowly. Although the size of this “bank” of CFC-11 is not exactly known, it is accounted for by the protocol, and this is one of the reasons why full ozone recovery will take decades.
The new articles, published in the journal Nature, also do not take into account the global increase in CFC-11 emissions that has occurred since 2013. The gas may still be 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 sure.
“This is a useful lesson that we really need to expand our monitoring capability,” said Dr. Rigby said.
Avipsa Mahapatra, a leading climate campaigner for the Environmental Investigation Agency, said of the new findings that it was “exciting to see atmospheric studies confirming that intelligence on the spot and subsequent enforcement resulted in a spectacular climate victory.” But she said her group has indications that the application could be more successful in some parts of China than others. “This is not the time for complacency,” she said.
Susan Solomon, an atmospheric chemist at the Massachusetts Institute of Technology who was not involved in the research, said the work is a true triumph for science. ‘
But the problem is not over yet, said dr. Solomon said because in addition to CFC-11, other similar chemicals are also being released. “There’s a whole zoo with molecules,” she said, and although the quantities are smaller, they add up.
These are also powerful greenhouse gases, she said, although their contribution to warming is much less than the much more prevalent gases such as carbon dioxide and methane. “The chemical industry worldwide is still not being closely monitored so that we can have confidence in how much greenhouse gases they produce and how many ozone-depleting gases they produce,” she said.
Liu Yi contributed research.