Arctic Science Journeys
Radio Script
1996

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Winter Ozone Loss
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STORY: The winter of 1996 is finally over. The bitter cold and snowfall in parts of the United States and northern Europe are now just entries in the record books. But the season set other records, too. Researchers say ozone loss in the atmosphere over Norway and England this winter allowed the highest levels yet of harmful ultraviolet radiation from the sun to reach the earth.

Joe Waters is a senior research scientist at the California Institute of Technology.

"There's certainly no question that this winter, of the winters we've been looking at ozone, there's been more ozone loss than we've ever seen before."

Ozone is a natural compound in the upper atmosphere that shields the earth against ultraviolet, or UV, radiation. Industrial chemicals called CFCs have weakened this shield, but scientists say an unusually cold mass of air called the Arctic Vortex accelerated the loss. Dan Jaffe is an atmospheric scientist at the University of Alaska Fairbanks.

"When you think of the atmosphere as a fluid or an ocean, it's a pool of air that doesn't mix very well and so because we don't have much sunlight of course the air is continuously cooling. The polar stratospheric clouds that are required to form for ozone depleting reactions to occur are only formed at very cold temperatures."

And when it got cold enough for those clouds to form, the chemicals in the atmosphere went to work destroying the ozone layer, says Jaffe. But to put things into perspective, ozone isn't disappearing throughout the Arctic. Rather, the losses were greatest over northern Europe, where the Arctic vortex is strongest. Conversely, the ozone layer over Alaska was not greatly affected.

"The ozone levels over Scandinavia and Northern Russia have typically been rather low, and we believe this is associated with both meteorology and CFCs ultimately. And the ozone levels over Alaska have been just slightly low, so that there is a much stronger influence on their side of the Arctic than on our side."

Even with so much ozone lost over the Arctic, Jaffe says losses over the South Pole, where winters are colder still, have been even worse.

"Over the last couple of years we've seen as much as 30-40 percent ozone loss over like northern Scandinavia and northern Russia. Whereas over the southern Hemisphere, the South Pole, we've seen ozone loss of 60-70 percent."

Scientists say ozone depletion, just like the weather, varies each year. An international agreement to ban CFCs should eventually eliminate this major contributor to the problem. As pollution declines,the ozone layer should rebuild itself. But scientists warn it may take fifty years to return to normal. For Arctic Science Journeys, this is Debra Damron.