Study: Despite efforts, ozone layer will take long time to heal

December 19, 2000
Web posted at: 1:33 PM EST (1833 GMT)

In this story: Environmental double whammy Bromine even harder on ozone Good and bad news RELATED STORIES, SITES

By Greg Lefevre
CNN San Francisco Bureau Chief

SAN FRANCISCO, California (CNN) -- For decades we've been cutting out use of aerosol cans and foam cups because the chemicals in them -- CFCs -- harm the atmosphere. Now there's new science that says recovery of the ozone layer may take not just several years, but perhaps half-a-century or more.

In a study presented this month at the American Geophysical Union conference in San Francisco, scientists say they were stunned by findings that up to 70 percent of the ozone layer over the North Pole has been lost.

"Even though levels of organic chlorine in the stratosphere are going down, we saw severe ozone depletion in the Arctic this past winter," said National Oceanic and Atmospheric Administration scientist Dale Hurst, who analyzed the data.

	VIDEO
CNN's Greg Lefevre reports that the ozone layer's recovery will take much longer than was thought Play video (QuickTime, Real or Windows Media) Watch the changing ozone levels from the winter of 2000 Play video (QuickTime, Real or Windows Media)

If the world has been reducing CFC emissions, why is it still so bad up there? The recovery, it seems, was been slowed -- nearly stalled -- by very cold winters in the Arctic's upper atmosphere.

Scientists at NASA's Goddard Space Flight Center say the extreme cold in the Arctic stratosphere only exacerbates ozone depletion.

Atmospheric physicist Paul Newman says the cold slows the dissipation and decay of CFCs and causes them to destroy ozone faster.

"We've polluted the stratosphere with these chlorine and bromine compounds, and because it's now colder, and because we have this change in the climate, we're getting more ozone loss than we would have gotten in a normal year," Newman said.

Newman said the data came from a winter-long project that involved scientists from the United States, Europe, Russia and Japan.

"We had a big campaign going up in the Arctic to look at how ozone was changing and what's causing ozone to change in the Arctic stratosphere," he said. "We had about 350 people up in Kiruna, Sweden, to look at this problem and we flew a commercial airliner up over the higher Arctic -- we flew the civilian version of the U2 spy plane up over the Arctic and out over Russia for the first time."

Protection of the ozone layer is important to the protection of human life. Ozone reduces ultraviolet radiation, the kind that burns skin. Loss of that protection has predictable results, Newman says. "Skin cancer rates will go up. Sunburns will occur at a faster rate, degradation of plastics and so forth, because of enhanced ultraviolet radiation from a lowering of ozone."

International agreements like those in the Montreal Protocol of 1987 have significantly slowed the use of chlorine around the world. But bromine, a chemical cousin to chlorine and used for some of the same purposes -- fire fighting, infection control and sanitation -- has not been regulated as strictly.

NOAA believes bromine is 45 times more damaging to ozone in the atmosphere than chlorine, but has not been subject to the same restrictions because many countries could not stand the loss of income from its stricter regulation.

Some scientists, however, believe governments will be under growing pressure in the coming years to limit the chemical.

In a paper presented to the AGU, Newman said it appears the amounts of chlorine and bromine "have peaked or nearly peaked at all levels in the stratosphere." The growth in chlorine emissions was slowed mostly by virtually eliminating the use of methyl chloroform, commonly used in food packaging and refrigeration, over the past decade.

But, NOAA's Hurst finds it hasn't done much good yet. "Because the levels of chlorine in the stratosphere are going down we hoped to see some start to the recovery of the ozone layer, however what we found in the Arctic this past winter was a severe ozone hole," Hurst said.

"That is kind of a wakeup call that although we have cut emissions of ozone depleting chemicals, that these ozone holes may continue for a long time into the future."

When asked how long the holes may continue, Hurst said: "Possibly another 50, 60 or seventy years."

Further reductions, the scientists fear, will be harder to come by because the easy changes have already been made.

And the North Pole may recover at a different rate from the South Pole because its weather varies more widely. The North Pole is surrounded by continents that constantly generate a variety of weather conditions. Those frequent storms are what cools the upper atmosphere at the North Pole.

For example, says Newman, huge storms generated over the Tibetan Plateau in western China sweep massive amounts of hyper-cold air into the Arctic atmosphere.

"You get changing weather systems. That leads to a colder polar stratosphere, which then causes more of these clouds to appear that activate chlorine. Chlorine destroys ozone."

Hurst says adequate improvement won't happen for at least a couple of generations. "That effect will be with us for at least the first half of this century."

German bid to keep greenhouse gas pledge
October 18, 2000
Scientists divided over ozone hole depth
October 10, 2000
NASA finds largest-ever ozone hole
October 4, 2000
Smog spells invisible damage for crops
June 27, 2000
Arctic SOLVE mission living up to its name
January 27, 2000

NASA images of the ozone layer
Sage III Ozone Loss and Validation Experiment

Note: Pages will open in a new browser window

External sites are not endorsed by CNN Interactive.