What is left unstated here is whether China plans to do anything about these dangerous chemicals.
A troubling spike in emissions of a globally banned chemical that damages the Earth’s protective ozone layer has been traced to two provinces in eastern China, according to a study published Wednesday that has alarmed scientists who monitor the planet’s atmosphere.
The study, published in the journal Nature, comes one year after another report revealed that air samples had shown a startling excess of a type of chlorofluorocarbon known as trichlorofluoromethane, or CFC-11, since 2012.
This manufactured chemical, once widely used to blow polyurethane into a rigid insulating foam, leaks into the air and destroys ozone molecules in the upper atmosphere. The ozone layer is critical to life, limiting the amount of harmful ultraviolet solar radiation that reaches the planet’s surface. CFC-11 is also a potent greenhouse gas, with roughly 4,750 times the heat-trapping potential of carbon dioxide.
The new report underscores the need for enforcement of international environmental agreements even when the hazards are clear and profound. And it is a reminder that China’s intensifying environmental challenges have global consequences.
“This is a huge problem,” a State Department official said Wednesday. The official said the department plans to review the report but has not yet concluded that China is the source of the new emissions.
“If it’s a problem in another country, we’re also going to be suffering,” the official said.
Any production and use of CFC-11 is a violation of the Montreal Protocol, a 1987 agreement that phased out such chemicals in favor of ones that do not damage the atmosphere. The global accord was reached after scientists revealed the existence of an expanding hole in the ozone layer over Antarctica.
Last year’s report did not identify the source of the new emissions beyond saying it is most likely they came from eastern Asia. But authors of the new report identify the provinces of Shandong and Hebei in eastern China as the likely source for at least 40 percent of the emissions.
The researchers based their conclusion on air samples from monitoring stations in South Korea and Japan. Those sampling stations, which feature instruments that can tease out the molecular components of the air, showed periodic spikes in CFC-11. The researchers combined that data with weather forecasts and observations of wind patterns and ran a series of computer models to pinpoint the most likely origin of the emissions. The results pointed to the two Chinese provinces.
“When the wind is blowing in a straight line from that source to the measuring station, you see a spike,” said lead author Matt Rigby, an atmospheric scientist at the University of Bristol.
“We hope to work with Chinese colleagues in the future to see if similar signals are visible in their data,” Rigby said.