Mysterious holes that periodically form in the ice covering Antarctic seas may serve as vents for excess heat and trapped gas, helping to shape the Earth's climate and influencing the "greenhouse effect."

These ice-free regions, some as large as France, weren't discovered until 1974 when scientists began examining new satellite images of Antarctica and the frozen ocean encircling it. Scientists don't know if the holes called polynyas existed before then or even how frequently they develop in the vast ice cover.Teams of scientists from the Soviet Union, the United States and West Germany have worked since 1981 to figure out how the holes form, what role they play in ocean cirulation and how they affect the climate.

Polynya (pronounced "pa-lean-yah"') is a Russian word used to identify an area in an ice field that is persistently free of ice, said Arnold Gordon, a professor of physical oceanography at Columbia University in New York.

Some oceanographers believe the Antarctic polynyas might play a role in the greenhouse effect that could have dire consequences in the coming century.