Scientists said the recovery of the ozone layer is back on track

In this way, the researchers said, rogue Chinese production contributed to “banks” of CFCs that were produced around the world before the ban went into effect and are found in foams as well as refrigeration equipment and fire-extinguishing systems. These chemicals are not yet present in the atmosphere, but are slowly being released through foam degradation and destruction, seeps, or other means.

Dr. Montzka said the size of the Chinese shareholding in banks is not known. “But if the banks have built substantially, that would add a few more years to that expected recovery delay,” he said.

Ending rogue emissions is another example of the success of the protocol, which is generally considered the most effective global ecosystem, said Dorwood Zelke, president of the Institute for Governance and Sustainable Development, a Washington-based research and advocacy organization. been enacted ever.

Mr. Zylke said monitoring of the atmosphere, required by the protocol, had detected the problem, and he had brought it to the attention of treaty management. “Without an admission of guilt, the offending parties joined forces,” he said. “And the measurements are back where they should be.”

Under protocol, assessments such as the one released on Monday are required to take place at least every four years. In addition to NOAA scientists, researchers from NASA, the World Meteorological Organization, the United Nations Environment Program and the European Commission were among the contributors.

The new assessment was the first to examine the effects on ozone of a potential type of climate intervention, or geoengineering, aimed at cooling the atmosphere. The method, called stratospheric aerosol injection, uses aircraft or other means to distribute sulfur aerosols high into the atmosphere, where they reflect some of the sun’s rays before they reach the surface.

The idea met fierce opposition. Among other objections, opponents say interfering with the climate in this way could have severe unintended consequences, potentially altering weather patterns around the world. But many scholars and others say that at least, Search is requiredbecause warming could reach a point where the world becomes desperate to try such a method of intervention, perhaps temporarily to buy time before cutting greenhouse gases has a significant impact.