Hole in ozone opens wide

By MIKE TONER The Atlanta Journal-Constitution

Published on: 10/20/06

The ozone hole over Antarctica reached record proportions this fall, breaking several years of relative improvement that followed the worldwide phase-out of ozone-destroying chemicals, NASA scientists announced Thursday.

"The average area of the ozone hole was the largest ever observed," said atmospheric scientist Paul Newman of NASA's Goddard Space Flight Center. By late September the hole — a severely depleted area of the protective ozone that shields the Earth's surface from harmful solar radiation — stretched over nearly 11 million square miles, which was 10 percent more than scientists were expecting.

David Hofmann, of the National Oceanic and Atmospheric Administration said by early October, ozone levels in the critical region of the stratosphere between eight and 13 miles of altitude were "virtually gone."

"It appears that the 2006 ozone hole will go down as a record setter," Hofmann said. "These numbers mean that the ozone is virtually gone from this layer of the atmosphere."

The seasonal ozone "hole," which appears early in the Antarctic spring, has been a closely watched phenomenon since it was first detected in the 1970s.

Because stratospheric ozone shields the Earth's surface from damaging solar radiation, which can cause skin cancer and disrupt biological processes, its depletion quickly became a cause for worldwide concern.

When man-made compounds, called chlorofluorocarbons or CFCs, were identified as the cause of ozone depletion, more than 180 nations, including the United States responded. In 1987, they signed a treaty to curb the production of CFC-containing refrigerants and other products.

Because the chemicals can persist in the atmosphere for 40 years, scientists have predicted that the ozone layer won't fully recover from the effects of CFCs until 2065.

The shrinking size of the springtime hole over the Antarctic since 2002 had encouraged them that the situation was improving, but NASA scientists say ozone losses also vary with fluctuations in the Antarctic stratosphere, which was colder than usual this year.

Satellite measurements of ozone losses show that the hole covers nearly all of Antarctica and reaches almost as far north as the southern tip of South America.