Ozone Spurs Arctic Warming, Scientists Find

March 15, 2006 — -- The Arctic has felt the impact from a pollutant normally associated with hot summers in big cities: ozone.

NASA researchers said they were surprised to discover that ozone is a much bigger contributor to Arctic warming than originally thought.

"We thought ozone was a minor player," said Drew Shindell, a climatologist with NASA's Goddard Institute for Space Studies. But Shindell said his new findings show that in the Arctic, ozone is responsible for up to 50 percent of the warming. "It was a big surprise."

In the upper atmosphere, ozone helps shield Earth from damaging radiation from the sun, but close to the ground it can cause respiratory problems, harm crops and contribute to global warming.

Shindell said the warming effect in the Arctic region occurs mostly in the winter and spring months, when winds carry the ozone from factories and cars in the Northern Hemisphere. The ozone doesn't have the same impact in the summer, Shindell said, when sunlight normally breaks it down.

The ozone there contributes to "feedback loops," in which a change occurs and then amplifies the original problem. One such loop occurs as the climate warms, leaving less white sea ice and snow cover on land to reflect the sun's energy. The darker land and water then absorb more heat energy, contributing to more warming.

Of particular concern, Shindell said, is the effect the warming may have on places like Greenland, which recent studies show is melting twice as fast as originally believed. If the entire Greenland ice sheet were to melt, which scientists say could take centuries, sea level could rise 21 feet.

But there is a bright spot. Shindell says that ozone may be an easier problem to tackle than carbon dioxide. "Ozone is a short-lived gas, and if we make changes to control ozone pollution, changes will occur almost immediately," he said. "Maybe we could slow down some of that rapid acceleration."

Also, on Tuesday the World Meteorological Organization in Geneva said that average concentrations of carbon dioxide, methane and nitrous oxide in the atmosphere "reached their highest-ever recorded levels in 2004."