Ozone hole is largest ever.

The seasonal hole in the ozone layer over Antarctica reached record proportions in September, according to a report by the World Meteorological Organization (WMO). Covering an area of 25 million square kilometers, or about 2.5 times the area of Europe, this year's hole surpassed the previous record - set in 1993 - by about 3 million square kilometers. The rift was also the "deepest" and fastest-growing ever, said WMO expert Rumen Bojkov. It involved the destruction of more than 85 percent of ozone in the lower stratosphere over an area of more than 10 million square kilometers.

Since the mid-1980s, the appearance of the ozone hole has become an annual occurrence during the Antarctic spring months, when cooler temperatures in the whirlpool-like polar vortex over the South Pole create conditions for accelerated ozone destruction. If these temperatures are unusually low, as they were in September, the depletion of the ozone layer caused by the release of chlorofluorocarbons (CFCs), halons, and other man-made chemicals into the atmosphere can cause the hole to expand even faster. "The hole was worse this year because the stratosphere was cooler," said David Hofmann of the U.S. National Oceanic and Atmospheric Association. "We experienced greater ozone loss around the edges and a large nibble from the top."

Without the protection of the ozone layer, humans and animals risk excessive exposure to UV-B radiation, which has been shown to cause skin cancer, eye abnormalities such as cataracts, and changes in the immune system that can make people more susceptible to cancer or infectious disease. Plants and marine life are also sensitive to UV-B radiation, which can damage marine ecosystems and reduce plant and fish yields.

Scientists predict that ozone depletion will reach its worst point during the next few years. The layer should then begin to heal and - according to the standard projections - return to normal around 2050. However, new evidence of a link between human-induced climate change and continued ozone depletion in the Arctic suggests that the recovery process could take even longer. According to a study in the April 9, 1998 issue of Nature, atmospheric buildup of the same greenhouse gases that contribute to global warming may also be causing cooling in the upper atmosphere, possibly contributing to the higher levels of ozone loss observed over the North Pole in recent winters. If this cooling trend continues, Arctic ozone depiction by 2020 could be roughly double what it would be without greenhouse gas increases, with the worst losses occurring between 2006 and 2021.

Because production of CFCs and other ozone-depleting substances has been almost completely phased out in industrialized countries, efforts to save the ozone layer now lie largely in the hands of developing countries and the former Soviet states. Under the 1987 Montreal Protocol and its subsequent amendments, developing countries are expected to freeze production and consumption of CFCs at average 1995-1997 levels by as early as next year, and then completely phase out production and use by 2010. The former Soviet states, which hope to achieve a similar target after failing to meet the 1996 phase-out deadline shared by other industrialized nations, recently received a $19 million dollar boost from 10 donor countries to speed up the process. The donation will be used to pay producers of ozone-depleting substances to close down their plants. The shutdowns are part of a global effort to control the lucrative black market in CFCs, which have been a continuing threat to ozone recovery efforts worldwide.