Hole In Ozone Layer Grows

The hole in the ozone layer is getting larger.

CBS News Correspondent John Roberts reports on how this could affect your health.

In Lauder, New Zealand, the air is so clean that on a clear day you can see forever.

At the National Institute of Water and Atmospheric Research, there are 60 kilometers, or almost 40 miles, of perfect conditions for scientists to turn their sights skyward.

On one recent clear day, researchers were looking deep into the fragile sheath of ozone that protects humans from the sun's harmful rays. The less ozone there is, the more cancer-causing ultraviolet light that reaches earth. And the researchers don't like how quickly the ozone hole is forming.

The news is perplexing. Despite international agreements that have reduced levels of aerosols and refrigerants that deplete ozone, the ozone layer is being destroyed even more rapidly than before.

"It should have started to level off, and so the fact that it hasn't leveled off leads us to suspect that there may be other factors at play," says Richard McKenzie of National Institute of Water and Atmospheric Research.

NASA scientist Drew Shindell of the Goddard Institute for Space Studies suspects the culprit is global warming caused by decades of pollution from factory emissions and car exhaust.

His groundbreaking research shows that as so-called greenhouse gases warm the lower level of the atmosphere, the upper level, where the ozone is, grows colder, creating conditions that are accelerating ozone depletion and substantially delaying its ultimate recovery.

In 1998 the hole in the ozone layer was the largest ever observed, Shindell says. "It was larger than the whole continent of North America," he says.

There is disturbing new evidence of the ozone problem. In New Zealand, which has typically enjoyed above-average levels of protective ozone, the amount of cancer-causing ultraviolet radiation that now reaches the earth has increased 12 percent in the past two decades.

The trend has dire implications in a country where outdoor adventure is a birthright.

"Even a 1 percent increase in UV can have rather a significant increase in skin cancers. For example, a 1 percent change in UV is thought to lead to a 2 percent increase in skin cancer," says McKenzie.

Around the world in the Northern Hemisphere, other stations have picked up signals that UV exposure is on the rise. And with global warming now projected to delay ozone recovery by at least 20 years, the health risks of this extended sunburn will be felt well into the next century.

For more on the global warming debate, go to the NASA Goddard Institute for Space Studies Web site.

For more on the increase in ultraviolet radiation, go to the National Institute of Water and Atmospheric Research Web site.