A mysterious spike of chemicals destroying ozone is traced in eastern China

Any production and use of CFC-11 constitutes a violation of the Montreal Protocol, a 1987 agreement that phased out these chemicals for the benefit of those who do not damage the atmosphere. The overall agreement was reached after the scientists had revealed the existence of an expanding hole in the ozone layer over Antarctica.

Last year's report did not indicate the source of new emissions, except that they probably came from East Asia. The authors of the new report said, however, that Shandong and Hebei provinces in eastern China would be the source of at least 40 percent of emissions.

The researchers based their findings on air samples from monitoring stations in South Korea and Japan. These sampling stations, which have instruments capable of extracting the molecular components of the air, showed periodic peaks of CFC-11. The researchers combined this data with weather forecasts and observations of wind patterns, and developed a series of computer models to determine the most likely source of emissions. The results highlighted the two Chinese provinces.

"When the wind blows in a straight line between this source and the measuring station, you see a spike," said lead author Matt Rigby, an atmospheric scientist at Bristol University.

Cyclists wait in 2016 to cross a road in Shijiazhuang, Hebei Province, in northern China, during a very polluted day. (GREG BAKER / AFP / Getty Images)

"We hope to work with Chinese colleagues in the future to see if similar signals are visible in their data," Rigby said.

The Montreal Protocol is often presented as a model for global cooperation on environmental protection and what countries can do collectively to combat climate change – another tragic common property crisis caused by fuel combustion fossils and other human resources. activity.

Parties to the protocol were alarmed by last year's report and called for "urgent action" to investigate sources of emissions and implement the international agreement.

"We can not relax our vigilance for a second. We can not let this issue go away, "said last summer Tina Birmpili, chief of the Ozone Secretariat for the Environment in the United States.

The protocol has largely worked as intended and the authors of the new report repeat this central message: the ozone layer continues to recover despite evidence of new emissions.

The problem is that recovery may occur more slowly than expected. The concentrations of CFC – 11 in the atmosphere did not decrease as fast as the computer models had predicted.

There may have been relatively benign explanations. Much of the CFC-11 is already "set aside" in the built world, in the form of an insulation that gradually lets gas escape into the atmosphere. Rigby and his colleagues discussed the possibility that new construction, replacement of buildings and the destruction of older infrastructure may have released chemicals into the air.

But the numbers have not been added. The most likely explanation is the new production and use of the chemical, he said.

Rigby said the new emissions of CFC-11 had the equivalent of CO2 emitted by human activity in global warming every year in the city of London.

Stephen Montzka, a scientist with the National Oceanic and Atmospheric Administration and co-author of Wednesday's study, as well as the 2018 report, said the latest findings leave important unanswered questions. Researchers have plotted about half of the CFC-11 emissions of concern in the two Chinese provinces, but details of the sources of other emissions remain unclear.

"The guessing game is this: where does the other half come from?" Said Montzka, noting that the study only detailed emissions in a limited region of China, which includes about a third of its population.

"Where does the rest come from? We do not know. "

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The rise in CFC-11 emissions raises further questions as to why anyone would still want to manufacture it. The short answer is that CFC-11 is favored by some companies because it is cheaper and more effective than climate friendly alternatives. This is the conclusion of a survey released last year by the Environmental Investigation Agency, a Washington-based environmental monitoring group.

The researchers spoke with representatives from 18 companies in 10 Chinese provinces who admitted to using the banned chemical. Six of these companies were in Shandong and Hebei.

After the release of new issues last year, Chinese authorities have cracked down on the illegal use of CFCs, seized 29 tons of chemicals and shut down dishonest factories, according to Avipsa Mahapatra, who works for the monitoring group .

But she said Nature's paper indicated that this seized material is only a fraction of what is produced and used. She added that her investigators had discussed with companies that hid their use of CFC-11, for example by exposing legal chemicals that could be presented to government inspectors.

"We are just beginning to understand the magnitude of the problem," she said.

Montzka said that he was puzzled by the return of CFC-11.

"The phase-out was supposed to take place in 2010 – and I think that's the case," he said. "Why did he come back?"

This could be a case where early detection of illegal production could lead to measures to limit its use, which would minimize the impacts on the ozone layer, he said. But since the chemical is generally leaking foam over decades, the scale of the problem remains unknown, Montzka said.

"It's quite possible that we have only seen the tip of the iceberg so far," Montzka said. "If what we have detected actually represents only a small fraction of the new additional illegal production produced since 2010, then the problem could be more serious than what we have detected so far."