- (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 http://nic.fb4.noaa.gov/. Click onto Stratosphere, then
click on Daily Total Ozone.