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admin October 7th, 2007

HOLE IN OZONE LAYER SHRINKS 30 PERCENT
By Dave Mosher
LiveScience
October 3, 2007

http://www.livescience.com/environment/071003-ozone-hole-shrinks.html

The gaping hole in Earth’s ozone layer has shrunk 30 percent in size
compared to last year, according to new measurements made by the European
Space Agency’s Envisat satellite.

The ozone layer loses about 0.3 percent of its mass annually, yet fluctuates
in its thinness through the year. The region of extremely reduced ozone
above Antarctica, popularly known as a “hole,” generally peaks in size
during September and October but regains its composure by the New Year.

Researchers are not certain if this year’s smaller ozone hole means the
radiation-blocking layer is healing.

“Although the hole is somewhat smaller than usual, we cannot conclude from
this that the ozone layer is recovering already,² said Ronald van der A, a
senior project scientist at the Royal Dutch Meteorological Institute in the
Netherlands.

This year, the ozone region over Antarctica dropped 30.5 million tons,
compared to the record-setting 2006 loss of 44.1 million tons. Van der A
said natural variations in temperature and atmospheric changes are
responsible for the decrease in ozone loss, and is not indicative of a
long-term healing.

“This year’s ozone hole was less centered on the South Pole as in other
years, which allowed it to mix with warmer air,” van der A said. Because
ozone depletes at temperatures colder than -108 degrees Fahrenheit (-78
degrees Celsius), the warm air helped protect the thin layer about 16 miles
(25 kilometers) above our heads.

While strides have been made to ban ozone-munching compounds, such as
chlorofluorocarbons (CFCs), the ozone layer continues to thin since the
problem was widely recognized in 1985. The layer helps absorb harmful
ultraviolet radiation from the sun, which increases the health risks of skin
cancer and cataracts, as well as poses harm to marine life.

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