For years, experts have warned that the Earth’s protective ozone layer is shrinking.
This week, CSU professor A.R. “Ravi” Ravishankara delivered some good news about the fragile shield of stratospheric gas: The ozone layer appears to be recovering.
The discovery was made by a panel of 300 scientists appointed by the United Nations to assess ozone depletion. Ravishankara helped lead the group, which has spent the past four years sifting through and analyzing ozone data and studies.
The panel attributed the turnaround to the “concerted international action” that took place in the wake of the 1987 Montreal Protocol. The agreement called for phasing out the use of chlorofluorocarbons (CFCs) such as Freon and other harmful chemicals in refrigerators, air conditioners, aerosols, foam manufacture, etc., around the world.
Based on their findings, the panel predicts the ozone layer should return to its 1980 level before the middle of this century – if current trends continue.
“We’ve seen evidence of ozone recovery and we believe that trend will continue if the international community continues to comply with the Montreal Protocol,” said Ravishankara, who participated in the Sept. 10 press conference announcing the findings at the United Nations in New York City.
Listen to Ravi at the U.N.
Protecting the ozone
The outermost layer of Earth’s atmosphere protects the Earth and its inhabitants from the sun’s most severe and harmful ultraviolet rays. Scientists began seeing signs of its depletion more than 30 years ago and attributed the decline to the use of CFCs and other ozone-depleting substances.
Since then, through international agreements, those chemicals have been replaced with other substances in everyday use.
United Nations officials say without the Montreal Protocol and other agreements, the level of harmful, ozone-depleting substances would have substantially increased and put humans at risk of higher rates of skin cancer, eye cataracts and other health problems.
But they also warned the problem is not solved. For example, many aerosol products now use hydrofluorocarbons – HFCs – instead of CFCs. Those HFCs do not deplete the ozone, but many are potent greenhouse gases.
“Given that ozone affects climate and climate affects ozone, it is now critical that the international community synergizes its work on climate change and ozone depletion,” said Achim Steiner, United Nations under-secretary-general and executive director of the UN Environment Program.
Heartened by the findings
Ravishankara and other members of the scientific assessment panel are expected to present their findings at the annual Meeting of the Parties to the Montreal Protocol in November in Paris.
This is the fifth United Nations ozone assessment in which the CSU professor has been involved and his second as a co-chair. The United Nations appoints the panel every four years to study the state of the ozone and release a report called the Scientific Assessment of Ozone Depletion.
Ravishankara, an atmospheric chemist who has studied ozone since the 1970s, said he was very heartened by the findings.
“It is evidence that humans can take action and have an impact,” he said.
Did you know?
Ravishankara will participate in online chat about the state of the ozone layer on Monday, Sept. 15 through the United Nations Environmental Program’s “Ask an Expert” initiative. The topic is in honor of World Ozone Day on Sept. 16.