Antarctic Ozone Hole
Now Twice The Size
Of North America
From Gerry Lovell <>
(Reuters) US government scientists said on Tuesday this year's "ozone hole" over Antarctica was the largest ever observed, leaving an atmospheric depletion area greater than the size of North America over the southern land mass.
Commerce Department scientists at the National Oceanic and Atmospheric Administration (NOAA) and the NASA space agency said the current "hole" measured 26 million square kms, compared to last year's 19 million square kms.
Increased amounts of the sun's ultraviolet radiation that reaches the earth surface because of ozone loss have the potential to increase rates of skin cancer and cataracts in humans, harm some agricultural crops and interfere with marine life, according to NOAA.
Since the early 1980s, scientists have gauged the hole by using satellite instruments and weather balloons.
The so-called hole is actually a region of ozone depletion that results from complex chemical and meteorological processes in the the earth's stratosphere.
Since the ozone hole was first spotted, the United Nations Montreal Protocol on substances that deplete the ozone layer was adopted, in 1987. The treaty was approved to curb the release of ozone-depleting agents into the atmosphere.
Scientists will make observations to detect changes in the amount of ozone and the protocol's impact over the next decades, said Walter Plant, a physicist at NOAA's National Environmental Satellite, Data and Information Service.
Researchers expect the Antarctic ozone hole to remain severe for the next 10-20 years and be followed by a period of slow healing. Full recovery is predicted to occur in 2050, but climate change will affect the rate of recovery.
Values of the amount of ozone over a large portion of Antarctica are currently around 100 Dobson units -- the amount of ozone in a column directly over the surface of the earth at a given location -- compared with the average global value of about 330 Dobson units, NOAA said.
NOAA also announced that an image of this year's ozone hole over Antarctica can be seen on the World Wide Web. The address is Click onto Stratosphere, then click on Daily Total Ozone.