Roger Harrabin BBC 10 Sep 14;
The ozone layer that shields the earth from cancer-causing ultraviolet rays is showing early signs of thickening after years of depletion, a UN study says.
The ozone hole that appears annually over Antarctica has also stopped growing bigger every year.
The report says it will take a decade before the hole starts to shrink.
Scientists say the recovery is entirely due to political determination to phase out the man-made CFC gases destroying ozone.
The study was published by researchers from the World Meteorological Organization (WMO) and the UN Environment Programme (UNEP).
"International action on the ozone layer is a major environmental success story... This should encourage us to display the same level of urgency and unity to tackle the even greater challenge of tackling climate change," said WMO Secretary-General Michel Jarraud.
Dr Ken Jucks from the US space agency Nasa told BBC News that humans "have started to do the right thing in order to convert the atmosphere back towards what it was before the industrial revolution started".
Scientists cannot be absolutely certain yet that the hole will heal itself. Prof David Vaughan from the British Antarctic Survey (BAS) said that test results from his organisation would throw extra light on the WMO's
"We have to be a bit cautious, but this does look on the face of it like some very good news," he told BBC News. "Our own data from the Antarctic will take a few weeks to process but we hope to confirm the findings. If it's accurate, it underlines the potential power of international agreement."
CO2 still problematic
The good news on ozone comes in the wake of bad news on the gases fuelling climate change. The WMO said this week that atmospheric greenhouse gases had reached a record high.
Tackling a gas like carbon dioxide (CO2) which is central to so many facets of human life is of a completely different order to reducing a few chemicals for which substitutes can be found.
The 1987 Montreal Protocol that banned or phased out ozone-eating depleting chemicals, including chlorofluorocarbons (CFCs) once widely used in refrigerators and spray cans, would prevent two million cases of skin cancer annually by 2030, according to UNEP.
It would also help prevent damage to wildlife, agriculture, peoples' eyes and immune systems, the agency added.
The WMO say ozone should recover towards its 1980 level by mid-century, or slightly later for Antarctica, where it gets dangerously thin every year between mid-August and November or December.
It says progress could be improved by as much as 11 years if existing stocks of ozone-depleting substances - many of them stored up in old fridges and fire-extinguishers - were destroyed.
Fragile ozone layer shows first sign of recovery : U.N
Tom Miles PlanetArk 11 Sep 14;
Experts said it was largely down to global action - a 1987 ban on man-made gases that damage the fragile high-altitude screen. The agreement would help prevent millions of cases of skin cancer and other conditions, they added.
The ozone hole that appears over Antarctica has also stopped growing bigger every year, though it will be about a decade before it starts shrinking, said the report co-produced by the World Meteorological Organization and the U.N. Environment Programme.
"International action on the ozone layer is a major environmental success story ... This should encourage us to display the same level of urgency and unity to tackle the even greater challenge of tackling climate change," said WMO Secretary-General Michel Jarraud.
Past studies have suggested the ozone layer has stopped getting worse.
"Now for the first time in this report we say that we see indications of a small increase in total ozone. That means recovery of the ozone layer in terms of total ozone has just started," said WMO senior scientific officer Geir Braathen.
The 1987 Montreal Protocol that banned or phased out ozone depleting chemicals, including chlorofluorocarbons (CFCs) once widely used in refrigerators and spray cans, would prevent 2 million cases of skin cancer annually by 2030 according to UNEP.
The agreement would also help avert damage to wildlife, agriculture, human eyes and immune systems, the agency added.
CLIMATE IMPACT
The ozone layer was expected to recover toward its 1980 level by mid-century, or slightly later for Antarctica, where it gets dangerously thin every year between mid-August and November or December.
"The development you saw during the 1990s that the ozone hole got bigger from year to year - that development has stopped, so it has leveled off," said Braathen.
"We think in about 2025 or thereabouts we'll be able to say with certainty that the ozone hole is getting smaller," he added.
Progress could be sped up by as much as 11 years if existing stocks of ozone-depleting substances - many of them stored up in old fridges and fire-extinguishers - were destroyed.
The largest ozone hole on record was about 30 million square km in 2006. The hole now covers about 20 million square km - big enough for the moon to pass through - but may not have peaked this season.
The size of the hole varies from year to year, partly due to temperature in the upper atmosphere.
The reduction of ozone-damaging chemicals would also help the environment, the report said, as many of the substances were also greenhouses gases blamed for global warming.
But the rising levels of other greenhouses gases in the atmosphere had "the potential to undermine these gains," said the report.
One of the ozone-depleting substances that was supposed to have been phased out - carbon tetrachloride, a solvent - was still being released into the atmosphere suggesting, the report said, illicit production and usage over the past decade.
(Reporting by Tom Miles; Editing by Andrew Heavens)
