October 4, 2000. Copyright 2000. Graphic News. All rights reserved.

MONSTER MILLENNIUM OZONE HOLE

LONDON, October 4, Graphic News: THE ANNUAL depletion of ozone high over the Antarctic has steadily worsened over the past 10 years and has reached a record depth this year, say meteorologists.

Fresh data from the British Antarctic Survey (BAS) comes just weeks after the U.S. space agency NASA said the largest hole ever seen had opened up over Antarctica, a sign that greenhouse gases are taking their toll on the earthÕs protective layer.

Ozone levels at the BAS Hailey station have dropped to around half of the value expected in early September.

For more than a decade, the annual hole in the earthÕs protective layer has appeared in late August or early September, with the phenomenon peaking in the first week or two of October.

During the past four weeks, all 12 monitoring stations around the rim of the Antarctic have reported measurements of ozone that are 50-70 percent below the norms in the years 1964-1976, before the ozone hole was detected.

The Millennium ozone hole covers almost 11.5 million square miles (30 million square kilometres), an area three times larger than the land mass of the United States, the BAS reported.

ÒIt is now the largest ever recorded,Ó it said. The previous record was approximately 10.5 million square miles, in 1998.

Ozone molecules -- a three-atom form of oxygen -- comprise a thin layer of the atmosphere that shields against harmful ultraviolet rays from the sun. Its destruction, first spotted in 1985, is due to pollution by chlorine or bromine from human-produced chlorofluorocarbons (CFCs). 

Measurements made with balloon-borne instruments show a nearly two-third depletion of ozone.

In the critical 6-14 mile (9.6-22.5 kilometre) altitude region ozone is almost totally destroyed. This is where clouds form in the extremely cold (minus 80 degrees Centigrade, minus 112 degrees Fahrenheit) stratosphere during the six-month darkness of Antarctic winter. These clouds contain ice particles which provide a surface upon which unusual chemistry occurs, chemistry that allows the reactive chlorine and bromine atoms brought to the stratosphere by CFCs to do their destructive work.

This yearÕs monster hole may have been caused by a change in a swirling high-level air current over Antarctica, a sort of polar jet stream that circles the area and contains the ozone hole.

The 2000 version of this air current extends farther north than it has in the past, said Paul Newman, who works with NASAÕs Total Ozone Mapping Spectrometer (TOMS) instrument aboard a NASA satellite.

ÒThe containment is bigger, so the ozone hole is bigger,Ó Newman said. ÒWe're not really sure why that happened.Ó 

This record ozone hole comes a month before ministers gather in The Hague to discuss progress on implementing a U.N. framework convention on climate change.

Governments are under pressure to comply with pledges made in Kyoto in 1997 to curb emissions of greenhouse gases like carbon dioxide and CFCs that are blamed for global warming and other extreme weather patterns.
/ENDS
Sources: British Antarctic Survey, NASA, Reuters, Associated Press