• The ozone layer that shields life from cancer-causing solar rays is recovering at a rate of one to three percent per decade, reversing years of dangerous depletion caused by the release of harmful chemicals.
• The four-yearly review of the Montreal Protocol, a 1987 ban on man-made gases that damage the fragile high-altitude ozone layer, found long-term decreases in the atmospheric abundance of controlled ozone-depleting substances and the ongoing recovery of stratospheric ozone.
The Antarctic ozone hole
• The Antarctic ozone hole is recovering, while continuing to occur every year.
• As a result of the Montreal Protocol much more severe ozone depletion in the polar regions has been avoided.
• The Antarctic ozone hole was expected to gradually close, returning to 1980 levels in the 2060s.
• Evidence presented by the authors shows that the ozone layer in parts of the stratosphere has recovered at a rate of 1-3 percent per decade since 2000.
• U.N. Environment and the World Meteorological Organization said in a statement. “At projected rates, Northern Hemisphere and mid-latitude ozone is scheduled to heal completely by the 2030s followed by the Southern Hemisphere in the 2050s and polar regions by 2060.”
• The U.N. had already hailed the success of the Protocol, which banned or phased out ozone depleting chemicals, including chlorofluorocarbons (CFCs) once widely used in refrigerators and spray cans.
• The report said it was the first time that there were emerging indications that the Antarctic ozone hole had diminished in size and depth since 2000.
• In the Arctic, annual variations were much larger, making it hard to confirm whether there had been a definite recovery in the layer since 2000.
• However, while most of the banned gases have been phased out, the report found at least one violation of the protocol.
• It’s an unexpected increase in production and emissions of CFC-11 from eastern Asia since 2012.
• The report said the source country or countries had not yet been identified.
• If CFC-11 emissions continued at the same rate, return of mid-latitude and polar ozone-depleting chemicals to their 1980 values would be delayed by about 7 and 20 years, respectively.
Mains Paper 3: Environment
Prelims level: Ozone layer
Mains level: Read the attached story