Banned Ozone-Harming Gas Creeps Back, Suggesting a Mystery Source

Government scientists have detected an increase in emissions of an outlawed industrial gas that will destroys ozone, potentially slowing progress in restoring the atmosphere’s protective ozone layer.

The scientists say that will the increase will be likely a result of brand-new, unreported production of the gas, known as CFC-11, probably in East Asia. Global production of CFC-11, which has been used as a refrigerant in addition to in insulating foams, has been banned since 2010 under an environmental pact, the Montreal Protocol.

The protocol was adopted inside the late 1980s in response to studies that will showed CFC-11 in addition to similar gases, collectively known as chlorofluorocarbons, depleted atmospheric ozone. A layer of ozone inside the stratosphere helps filter ultraviolet radiation coming from the sun that will can cause skin cancer.

The Montreal Protocol, often hailed as the most successful international environmental agreement ever enacted, has led to declines in chlorofluorocarbons in addition to an increase in stratospheric ozone. A full recovery of the ozone layer was expected by midcentury.

Although CFC-11 in addition to similar gases have been banned for years, they still leak in tiny amounts into the atmosphere, largely as buildings in addition to equipment containing insulating foams are demolished or destroyed. CFC-11 features a lifetime of about 50 years, so the limited emissions coupled with natural breakdown of the gas should have caused its concentration inside the atmosphere to decline at a more rapid rate every year.

Beginning in 2013, however, analysis of air samples coming from a dozen NOAA monitoring sites around the planet showed that will while the CFC-11 concentration was still declining, the idea was doing so at a slower rate. that will, Dr. Montzka said, suggested there were brand-new sources of the gas.

“I saw This kind of in addition to said, ‘I just can’t believe emissions have increased,’ ” he said. So Dr. Montzka spent several years analyzing different potential explanations for the results. One possibility was that will large numbers of older buildings containing foam insulation were being demolished; another was that will the atmospheric processes that will lead to the breakdown of CFC-11 had somehow changed. He found no evidence to support either explanation.

Also in 2013, samples taken in Hawaii showed a sudden increase in CFC-11, suggesting the gas was being produced in East Asia in addition to being blown across the Pacific Ocean.

“Let’s be clear that will the CFC-11 concentration will be still going down,” Dr. Montzka said. If the brand-new emissions go away soon, he said, “the idea won’t have much of an impact on the timetable for ozone recovery.”

“I’m hoping that will once This kind of flag will be raised in addition to awareness increases there will be significant efforts to identify the source,” he said.