For years, the Cassandras have warned the world that the ozone layer is depleting. But the doomsayers may have jumped the gun. Last week, two UN agencies laid to rest such predictions of a looming climate catastrophe when they announced that the ozone layer that girdles the earth and protects it from the sun’s harmful radiation is not depleting anymore. On the contrary, it has begun healing itself. The gaping holes in the layer will fill themselves, though at a pace slower than earlier believed.

But at the end of the mending process, there will be no holes anymore. To be sure, the World Meteorological Organisation (WMO) and the United Nations Environment Programme (UNEP) had announced the good news in 2002. Last week’s report by the two estimated when exactly the reversal in the ozone layer’s plight would take place. The two agencies will publish their final report next year.

Still, the announcement is clearly good news. Scientists have for years sounded the alarm bells on global warming, which again is triggered by human emissions of greenhouse gases. As the UN agencies estimate that the levels of these harmful gases — carbon dioxide, methane, nitrous oxide and chlorofluorocarbons (CFCs), gases used in refrigerators and airconditioners — will drop, their impact too is expected to be far smaller. These gases trap heat in the lower atmosphere and do not let them escape to the outer atmosphere. “If the trend of emission of greenhouse gases goes down, it is also going to make the earth less warmer. This reversal is a happy thing,” says Prof. Shyam Lal, chairman of the Space and Atmospheric Science Division of the Physical Research Laboratory at Ahmedabad.

This, in turn, also means that the impacts of global warming — rising sea levels, extreme weather events like heat waves, frost, drought, storms, extinction of species, loss of forests and glacial retreat — will progressively become less severe.

Lal, who has been measuring CFCs and tropospheric ozone levels in India since the 1980s, says though it is going to take a “life time”, the reversal is on estimated lines and very encouraging.

The latest development also implies that school textbooks a few years hence will not include scary scenarios like “Holes in the ozone layer increase the risk of skin cancer and cataracts in human beings.” Last but not least, it backs the initiatives of those behind the Montreal and Kyoto Protocols on climate change, which committed signatory nations to progressively banning the use of ozone-harmful products like CFCs.

The joint report was prepared by 250 scientists worldwide who were studying the effects of the Montreal Protocol. The good news is that the worst affected regions in Antarctica, where the “holes” have grown larger in the last three decades, will recovery fully. The bad news: this will come about only after 2065, 15 years later than scientists had earlier estimated. Because of special conditions within the Antarctic vortex — a natural cyclone of super-cold and fast winds — the ozone-depleting gases will take longer to be removed.

Likewise, by 2049, large areas over Europe, North America, Asia and southern Australia, Latin America and southern Africa will have their layer repaired back to what it was pre-1980. This again is five years later than forecast in the last major scientific report in 2002.

The new report says the delay in repairing the ozone layer is mainly the outcome of increased amounts of some types of CFCs not immediately banned under the Montreal Protocol. These gases are still in use. Also, a relatively safer groups of CFC substitutes (HFCF-22 or hydrochlorofluorocarbons) which still cause some depletion will be used more in the future. The ozone, a friendly gas, is depleted by the chemical action of chlorine and bromine released by CFCs.

The repair has been achieved because of the early removal of shorter-lived harmful gases like methyl chloroform and methyl bromide, the report says.

Amidst the cheer, however, the delayed recovery of the ozone layer has left behind an embedded warning — one can’t take the ozone layer for granted. In the efforts to phase out harmful chemicals, complacency can’t set in. “While these latest projections of ozone recovery are disappointing, the good news is that the level of ozone-depleting substances continues to decline from its 1992-94 peak in the troposphere and the 1990s peak in the stratosphere,” WMO secretary-general Michel Jarraud said after releasing a synopsis of the report.

Even so, not everybody is hurrahing. Consumer activist Rajat Choudhury, who has been working on ozone-depleting substances for a long time, warns that despite the rosy picture being painted by the UN agencies, countries that have signed the Montreal Protocol should not let their guard down. “In a study sponsored by the Union Ministry of Environment and Forests last year, we found that many multinational companies still use ozone-unfriendly substances in India. The technology they use for making ACs and refrigerators for markets in developed countries is different from what they use for developing countries. Even if some substances are ozone-friendly, they might not be climate friendly.”

Consumers, too have a big role to play in using the right equipment. “Since eco-marking (labelling products as ozone-friendly or climate-friendly) is not mandatory, there is absolutely no compliance,” Choudhury adds.