The recovery of the ozone hole over Antarctica is likely to be delayed by the illegal production of an ozone-destroying gas in China, according to the first assessment of the banned chemical’s impact.
In the worst case, the recovery will be delayed by around 18 years if production of trichlorofluoromethane (CFC-11), used to make foam insulation in fridges, continues unabated. But such an extreme scenario is seen as unlikely because of signs Chinese authorities have begun cracking down on the problem.
If production of the gas is phased out over the next decade, which seems more likely, the result would be a two-year delay in the ozone hole’s recovery, says Martyn Chipperfield at the University of Leeds, UK. Were production to stop immediately, there will be virtually no impact on its recovery, according to modelling by his team.
That is because the increase in CFC-11 emissions took place between 2013 and 2017, which was noticeable but not enough to have a large impact among all the other factors that affect ozone recovery. The ozone hole, which is usually open between September and November, is expected to recover by around 2060.
“We can get things back on track quite quickly. The implications for the ozone layer need not be too damaging,” says Chipperfield.
The new research follows scientists raising the alarm last year that CFC-11 levels in the atmosphere were rising, despite their production being banned internationally in 2010 under the Montreal Protocol. Researchers later pinpointed the source as the eastern China provinces of Shandong and Hebei, where it is believed CFC-11 has been illegally used to make foam.
Clare Perry at the Environmental Investigation Agency says that due to the response from China and the international community, “it’s highly unlikely that illegal CFC-11 production will continue at the same level in China, and therefore the 18-year delay is very unlikely”.
It seems CFC-11 emissions have already begun declining this year, according to preliminary findings by Stephen Montzka at the National Oceanic and Atmospheric Administration in Colorado, which were presented last month at a meeting of the parties to the Montreal Protocol in Italy.
“This current event, provided action is taken quickly, shouldn’t have too much of a long-term impact. That’s not to say we should get complacent,” says Matt Rigby at the University of Bristol, UK.
Chipperfield says it is important to keep an eye on a group of ozone-depleting chemicals known as very short-lived substances, which aren’t covered by the Montreal Protocol.