The huge hole in the ozone layer that is developing over Antarctica every year is set to be healed by 2066, according to a new study.
Earth’s protective ozone layer is healing at a pace that will completely close the hole over Antarctica in about 43 years, according to a United Nations report.
The scientific assessment, conducted every four years, found that a recovery is underway, more than 35 years after all the world’s nations agreed to stop producing chemicals that deplete the ozone layer in the Earth’s atmosphere. The layer shields the planet from harmful radiation linked to skin cancer, cataracts and crop damage.
“In the upper stratosphere and in the ozone hole, we’re seeing things getting better,” said Paul Newman, co-chair of the scientific assessment.
Progress is slow, according to the report, presented Monday at the American Meteorological Society meeting in Denver. The global average amount of ozone 30 km (18 miles) up in the atmosphere will not return to pre-1980 depletion levels until about 2040, the report said. And by 2045, things won’t be back to normal in the Arctic.
The huge hole in the layer that develops over Antarctica every year will not be fully patched until 2066, the report said.
This combination of images provided by NASA shows areas of low ozone over Antarctica in September 2000, left, and September 2018. The purple and blue colors are where ozone is least, and in the yellow and red colors there is more ozone [NASA via AP]
Scientists and environmentalists around the world have long hailed efforts to heal the ozone hole as one of humankind’s greatest ecological victories. The initiative grew out of a 1987 agreement called the Montreal Protocol, which banned a class of chemicals commonly used in refrigerants and aerosols.
“Ozone action sets a precedent for climate action,” World Meteorological Organization secretary-general Petteri Taalas said in a statement. “Our success in phasing out ozone-depleting chemicals shows us what urgent can and must be done to move away from fossil fuels, reduce greenhouse gases and thus limit temperature rise.”
Signs of healing in the ozone layer were reported four years ago, but were small and rather preliminary.
“These recovery numbers have become very solid,” Newman said.
The two main chemicals that eat up ozone are in lower concentrations in the atmosphere, said Newman, senior Earth scientist at NASA’s Goddard Space Flight Center.
Chlorine levels have fallen 11.5 percent since their peak in 1993, and bromine, which eats ozone more efficiently but is in less abundance in the air, has fallen 14.5 percent since its peak in 1999, they said in the report.
The drop in bromine and chlorine levels “is real testament to the effectiveness of the Montreal Protocol,” Newman said.
Natural weather patterns in Antarctica also affect the size of the ozone hole. In recent years, the holes have gotten a little larger because of these patterns, but the general trend is toward healing, Newman said.
A few years ago, emissions of one of the banned chemicals, chlorofluorocarbon-11 (CFC-11), stopped declining and were increasing. Rogue emissions were spotted in parts of China but have now receded where expected, Newman said.
A third generation of these chemicals, called HFC, was banned a few years ago, not because it would eat up the ozone layer, but because it is a heat-trapping greenhouse gas. The new report says the ban would prevent an additional 0.5 to 0.9 degrees Fahrenheit (0.3 to 0.5 degrees Celsius) of warming.
The report also warned that efforts to artificially cool the planet by forcing aerosols into the atmosphere to reflect sunlight would thin Antarctica’s ozone layer by up to 20 percent.