- A recent study by NASA has confirmed the recovery of the ozone layer due to the absence of chlorine from Chlorofluorocarbon(CFC) in the atmosphere.
- Findings of UN study:
- The study published in Geophysical Research Letters journal has confirmed the phenomenon by mapping the chemical composition of the atmosphere.
- The study revealed that chlorine levels declined by 0.8% each year between 2005 and 2016 and speculates that it could be the effect of the worldwide ban on the use of CFC.
- Previous research had hinted at the decrease in the depletion of ozone layer. Scientists believe that the ozone layer would fully recover by 2080.
- UN Findings:
- The UN report also said that ozone in parts of the stratosphere has recovered at a rate of 1-3 per cent since 2000.
- 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.
- Factors recovering Ozone Hole:
- Montreal Protocol: It banned 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 was expected to gradually close, returning to 1980 levels in the 2060s, the report said.
- In 2019, the protocol is set to be strengthened with the ratification of the Kigali Agreement which limits the production of hydrofluorocarbons (HFCs), ozone safe compounds that are potent greenhouse gases.
- The writers of the report found that, if the Kigali Amendment is fully implemented, the world can avoid up to 0.4 per cent of global warming this century, meaning that it will play a major role in keeping the global temperature rise below 2°C.
- 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, 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.
- The report noted that 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 seven and 20 years, respectively.