Newspaper article International New York Times

Ozone Hole Shows Signs of Shrinking, Scientists Say ; 29 Years after Global Ban of CFCs, Earth's Natural Sun Visor May Be Healing

Newspaper article International New York Times

Ozone Hole Shows Signs of Shrinking, Scientists Say ; 29 Years after Global Ban of CFCs, Earth's Natural Sun Visor May Be Healing

Article excerpt

Three decades after a treaty to phase out the use of chemicals known as CFCs, there are indications that the hole in the ozone layer is healing.

Nearly three decades after the world banned chemicals that were destroying the atmosphere's protective ozone layer, scientists said on Thursday that there were signs the atmosphere was on the mend.

The researchers said they had found "fingerprints" indicating that the seasonal ozone hole over Antarctica, a cause of concern since it was discovered in 1984, was getting smaller. Although the improvement has been slight so far, it is an indication that the Montreal Protocol -- the 1987 treaty signed by almost every nation that phased out the use of chemicals known as chlorofluorocarbons, or CFCs -- is having its intended effect.

Full recovery of the ozone hole is not expected until the middle of the century. "This is just the beginning of what is a long process," said Susan Solomon, an atmospheric chemist at the Massachusetts Institute of Technology and lead author of the study, published in the journal Science.

Ozone high in the stratosphere protects life on earth by absorbing damaging ultraviolet rays from the sun. But ozone is destroyed by reactions with chlorine and other atoms that are released by CFCs and similar chemicals, which were used for decades as refrigerants and propellants.

More ultraviolet radiation leads to increased incidence of skin cancers, cataracts and other health problems.

Scientists who pushed for the treaty always acknowledged that recovery of the ozone layer would be very slow, because CFCs linger in the stratosphere for a long time.

"Think of it like a patient with a disease," Dr. Solomon said. "First, it was getting worse. Then it stopped -- it was stable but still in bad shape."

Now, she said, "as molecules slowly decay away from the atmosphere, it's getting just a little bit better."

David Fahey, a research physicist at the National Oceanic and Atmospheric Administration who was not involved in the study, said Dr. Solomon's work "gives us a critical level of confidence that we are moving in the direction we want to see. …

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