Polar Ozone ‘Hole’ May Occur Elsewhere

Scientists reported Monday that the dramatic depletion of ozone in the atmosphere over Antarctica is “nature’s gentle warning” that similar, possibly health-endangering depletions could occur elsewhere in the world.

Members of an expedition working on the polar cap, speaking to a briefing in Washington via satellite from McMurdo Station, a scientific research facility in Antarctica, said they have “strong evidence” that the area of depleted ozone, known as a “hole,” is caused by a chemical process, not by winds or solar activity, as had been widely believed.

Susan Solomon, leader of the 13-person expedition, said that man-made chemicals such as those released by aerosols may be among the causes of the low ozone level. The ozone layer, located in the atmosphere about 20 to 30 miles above the Earth’s surface, is vital to the maintenance of human life as it filters out deadly ultraviolet solar radiation.

Called ‘Test Case’

Dan Albritton, a scientist with the National Oceanic and Atmospheric Administration, characterized the current research in Antarctica as a “test case” for future examples of ozone depletion around the world.

“If it comes down that chemistry is in fact an important role in this, then observing (ozone depletion) under the extreme conditions of Antarctica would be somewhat like a canary in a coal mine,” Albritton said. “It would tell us something earlier than if we had to wait to see similar signs elsewhere on the globe.”

Solomon’s team was sent to Antarctica in August after examination of old satellite data confirmed the unexpected finding of a British team that starting in the 1970s, ozone concentrations had fallen sharply each October, during the polar springtime. The satellite data indicates that 50% less ozone was observed in 1985 than a decade earlier.

Solomon said the expedition recorded a 40% monthly drop in ozone over “only 20 to 30 days” in September.

Cloud Evaporation

The research team, which includes scientists from the NOAA, the Jet Propulsion Laboratory, the University of Wyoming and the State University of New York, concluded that the hole’s annual appearance in October may be associated with the springtime evaporation of polar clouds in the stratosphere.

The group’s studies of the formation of the hole, which is roughly equal in area to the United States, contradict the theory that heightened solar activity leads to ozone depletion. Scientists earlier had hypothesized that brilliant spring sunshine, following the darkness of the polar winter, caused the ozone depletion.

According to the team’s data, however, the depletion of ozone is occurring at lower altitudes than those that would be affected by increased solar activity.

Likewise, tracings of aerosol particles indicate that there is “no evidence for the kind of upward motion needed to support” the theory that upward winds push part of the ozone layer into the stratosphere, Solomon said.

‘More Complex’

After reviewing the new research, she said she is “more concerned” about the ozone hole because the results indicate that the problem is “more complex” than previously believed.

Philip Solomon, another expedition member who is unrelated to Susan Solomon, cautioned that it is unlikely that the radical ozone depletion over Antarctica will spread to the rest of the globe. However, “we won’t be sure of this until much more experimentation,” he said.

The expedition will leave Antarctica in mid-November and release the final results of its study next February.

National Aeronautics and Space Administration scientist James Margitan acknowledged that recently collected satellite data shows that “there is a decline in ozone in the Arctic region centered roughly over Spitsbergen and Norway.” He also confirmed reports of a similar depletion in the ozone layer over Switzerland.