Vulnerable Ozone Layer in Slow Recovery

PARIS, France, September 16, 2002 (ENS) - The Earth's stratospheric ozone layer is recovering from the effect of chemical emissions, but it will remain vulnerable during the next decade, even if countries comply with international agreements to protect it, predicts a new scientific report released to mark International Ozone Day.


The ozone hole shows blue over Antarctica in this 2001 image. (Image courtesy NASA)
The preliminary four year report was released today in Paris by the United Nations Environment Programme and the World Meteorological Organization.

The 250 scientists from 37 countries who prepared the report are members of the scientific assessment panel of the Vienna Convention and its 1987 Montreal Protocol on Substances that Deplete the Ozone Layer.

They report that human influenced disturbances on Earth's protective shield are now "at or near their largest."

The ozone layer is essential to life as it shields planet Earth from the harmful ultraviolet-B radiation of the Sun. It also completely screens out lethal UV-C radiation.

More UV-B bombarding the Earth means more melanoma and non-melanoma skin cancers, more eye cataracts, weakened immune systems, reduced plant yields, damage to ocean ecosystems and reduced fishing yields, adverse effects on animals, and more damage to plastics.

Presenting the report in Paris, co-author Gérard Mégie, said, "These results confirm that the Montreal Protocol is achieving its objectives. During the next decades, we should see a recovery of the ozone layer."


Gérard Mégie (Photo courtesy France5)
But Mégie, who is co-chair of the panel and president of the French National Scientific Research Center, had a cautionary word to obey the protocol's emissions limits on chemicals such as the refrigerant chlorofluorocarbon (CFC) and related chemicals.

"The concentration of chlorine in the stratosphere has now reached a maximum and the ozone layer is still quite vulnerable, said Mégie. "It is therefore extremely important that the control measures in the Montreal Protocol are strictly respected by all."

Referring to the Antarctic "ozone hole" the report notes that during the last decade it has increased in size, but not as rapidly as during the 1980s.

Stating that the area of the ozone hole varies from one year to another, the scientists warn that, "it is not yet possible to say whether the area of the ozone hole has maximized."

They predict that, while another smaller ozone hole exists over the Arctic, "a future Arctic polar ozone hole similar to the Antarctic appears unlikely."

The report also examines the relationship between ozone depletion and global warming, concluding that the interaction is "difficult to predict."

Mégie said that the complex interactions between these two phenomena "indicate the need for a common policy to resolve the problems."

The ozone depletion and the greenhouse gas warming phenomenon share many common chemical and physical processes. For example, as the atmospheric concentration of CFCs decline because of the Montreal Protocol's provisions, their global warming effects will decline.

On the other hand, use of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) as substitutes for CFCs would cause the greenhouse warming contributions of these new compounds to increase.


Low Arctic ozone level shows blue. Winter 1999-2000. (Image courtesy NASA)
The executive summary of the UNEP/WMO reports that global observations of many HFCs and HCFCs, as well as of hydrogen fluoride (HF), confirm that these contributions to global warming are currently increasing.

Developed countries responsible for most ozone depleting emissions have now phased out use of most CFCs and related chemicals. To ensure these gains are not lost, it is now necessary that developing countries follow suit.

Marco Gonzalez, executive secretary of the Ozone Secretariat, said, "While the majority of developing countries seemed to be on course in terms of compliance with their individual phaseout schedules, some of them are still lagging behind."

Under the Montreal Protocol, developing countries are committed to reducing their consumption and production of CFCs by 50 percent in the year 2005, and by 85 percent in 2007.

By 2005 they must also reduce their consumption of halons by 50 percent, of the fumigant methyl bromide by 20 percent, the solvent carbon tetrachloride by 85 percent and methylchloroform by 30 percent.

China and India have now taken steps to eliminate the emission of ozone depleters. In May, the Indian government and UNEP launched a new initiative aimed at accelerating the phaseout of ozone damaging chemicals. Under the program, the four big Indian manufacturers of CFCs pledged to introduce new, cleaner, production technologies to halt emissions.

The Indian companies are backing a nationwide ozone public awareness scheme targeted at the thousand of small and medium sized companies that are part of the CFC supply chain. These include refrigerator makers and repairers, suppliers of air conditioning units, and users of products that contain the ozone depleting chemicals.