DENVER
\nEarth\u2019s protective ozone layer is slowly but noticeably healing at a pace that would fully mend the hole over Antarctica in about 43 years, a new United Nations report says.
\nA once-every-four-years scientific assessment found recovery in progress, more than 35 years after every nation in the world agreed to stop producing chemicals that chomp on the layer of ozone in Earth\u2019s atmosphere that shields the planet from harmful radiation linked to skin cancer, cataracts and crop damage.
\n\u201cIn the upper stratosphere and in the ozone hole we see things getting better,\u201d said Paul Newman, co-chair of the scientific assessment.
\nThe progress is slow, according to the report presented Monday at the American Meteorological Society convention in Denver. The global average amount of ozone 18 miles (30 kilometers) high in the atmosphere won\u2019t be back to 1980 pre-thinning levels until about 2040, the report said. And it won\u2019t be back to normal in the Arctic until 2045.
\nAntarctica, where it\u2019s so thin there\u2019s an annual giant gaping hole in the layer, won\u2019t be fully fixed until 2066, the report said.
\nScientists and environmental advocates across the world have long hailed the efforts to heal the ozone hole \u2014 springing out of a 1987 agreement called the Montreal Protocol that banned a class of chemicals often used in refrigerants and aerosols \u2014 as one of the biggest ecological victories for humanity.
\n\u201cOzone action sets a precedent for climate action. Our success in phasing out ozone-eating chemicals shows us what can and must be done \u2013 as a matter of urgency \u2014 to transition away from fossil fuels, reduce greenhouse gases and so limit temperature increase,\u201d World Meteorological Organization Secretary-General Prof. Petteri Taalas said in a statement.
\nSigns of healing were reported four years ago but were slight and more preliminary. \u201cThose numbers of recovery have solidified a lot,\u201d Newman said.
\nThe two chief chemicals that munch away at ozone are in lower levels in the atmosphere, said Newman, chief Earth scientist at NASA\u2019s Goddard Space Flight Center. Chlorine levels are down 11.5 percent since they peaked in 1993 and bromine, which is more efficient at eating ozone but is at lower levels in the air, dropped 14.5 percent since its 1999 peak, the report said.
\nThat bromine and chlorine levels \u201cstopped growing and is coming down is a real testament to the effectiveness of the Montreal Protocol,\u201d Newman said.
\n\u201cThere has been a sea change in the way our society deals with ozone depleting substances,\u201d said scientific panel co-chair David W. Fahey, director of the US National Oceanic and Atmospheric Administration\u2019s chemical sciences lab.
\nDecades ago, people could go into a store and buy a can of refrigerants that eat away at the ozone, punch a hole in it and pollute the atmosphere, Fahey said. Now, not only are the substances banned but they are no longer much in people\u2019s homes or cars, replaced by cleaner chemicals.
\nNatural weather patterns in the Antarctic also affect ozone hole levels, which peak in the fall. And the past couple years, the holes have been a bit bigger because of that but the overall trend is one of healing, Newman said.
\nThis is \u201csaving 2 million people every year from skin cancer,\u201d United Nations Environment Programme Director Inger Andersen told The Associated Press earlier this year in an email.
\nA few years ago emissions of one of the banned chemicals, chlorofluorocarbon-11 (CFC-11), stopped shrinking and was rising. Rogue emissions were spotted in part of China but now have gone back down to where they are expected, Newman said.
\nA third generation of those chemicals, called HFC, was banned a few years ago not because it would eat at the ozone layer but because it is a heat-trapping greenhouse gas. The new report says that the ban would avoid 0.5 to 0.9 degrees (0.3 to 0.5 degrees Celsius) of additional warming.
\nThe report also warned that efforts to artificially cool the planet by putting aerosols into the atmosphere to reflect the sunlight would thin the ozone layer by as much as 20 percent in Antarctica.<\/p>\n","protected":false},"excerpt":{"rendered":"
DENVER Earth\u2019s protective ozone layer is slowly but noticeably healing at a pace that would fully mend the hole over Antarctica in about 43 years, a new United Nations report says. A once-every-four-years scientific assessment found recovery in progress, more than 35 years after every nation in the world agreed to stop producing chemicals that […]<\/p>\n","protected":false},"author":2,"featured_media":306734,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":{"0":"post-306723","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-world"},"yoast_head":"\n