A sharp and mysterious rise in emissions of a key ozone-destroying chemical has been detected, despite its production being banned around the world. Unless the culprit is found and stopped, the recovery of the ozone layer, which protects life on Earth from damaging UV radiation, could be delayed by a decade. The source of the new emissions has been tracked to east Asia, but finding a more precise location requires further investigation.
CFC chemicals were used in making foams for furniture and buildings, in aerosols and as refrigerants. But they were banned under the global Montreal protocol after the discovery of the ozone hole over Antarctica in the 1980s. Since 2007, there has been essentially zero reported production of CFC-11, the second most damaging of all CFCs.
CFCs used in buildings and appliances before the ban came into force still leak into the air today. The rate of leakage was declining steadily until 2013, when an abrupt slowing of the decline was detected at research stations from Greenland to the South Pole. The rise in CFC-11 was revealed by Stephen Montzka, at the US National Oceanic and Atmospheric Administration (NOAA) in Colorado, and colleagues who monitor chemicals in the atmosphere. “I have been doing this for 27 years and this is the most surprising thing I’ve ever seen,” he said. “I was just shocked by it.” Scientists then embarked on an investigation, published in the journal Nature, to find out the cause.
Michaela Hegglin, at the University of Reading, UK, and not part of the research team said researchers had taken rigorous steps to rule out alternative explanations for the rise in CFC-11 when reaching their conclusion that new production must be occurring.
She said: “The study highlights that environmental regulations cannot be taken for granted and must be safe-guarded, and that monitoring is required to ensure compliance.” Prof Piers Forster, at the University of Leeds, UK, said: “This new study is atmospheric detective work at its finest.”
[Source: The Guardian]