Date: 11/12/98  

Ancient bubbles of air trapped in polar ice are showing scientists that Earth's temperatures have jumped and dipped through the ages along with greenhouse gas levels.

Scientists at a meeting of the American Geophysical Union in San Francisco on Wednesday revealed their latest research on the Vostok Ice Core, a 3,546-meter-long sausage-like sample pulled from the Antarctic ice sheet at Russia's Vostok Research Station. Layers in the ice hold bubbles and microbes nearly 450,000 years old, an unmatched record of Earth's past.

"Understanding the past gives us insight into the future and the print man is leaving on the climate today," says Claude Lorius, of France's National Center for Scientific Research.

The core reveals at least three complete glacial cycles of global cooling that led to ice ages and then gradual warming. Charts of gas concentrations show Antarctic temperatures rise and fall in concert with the greenhouse gases carbon dioxide and methane.

What's unnerving are the chart's final squiggles: They show methane concentrations since the Industrial Revolution have shot up to nearly twice the highest concentration seen anywhere in the ice record. Today's carbon dioxide levels run perhaps higher than the highest figure evident in the core.

It's not yet clear whether temperature will continue to follow the gas levels, but "that's what we would infer from seeing concentrations of this degree,'' says geochemist Julie Palais of the National Science Foundation.

Microbiologists just in the last year have begun pulling bacteria, fungi and yeast from the ice, too, including some species unknown today.

Layers of ice from warmer periods seem to hold the most microbes and researchers believe different kinds of microbes probably reflect the different climates in which they flourished, making the tiny organisms clues to our planet's past, says Russian scientist Vladimir Kotliakov.

Researchers have even cultured some of the strange bugs in their laboratories.

"We don't know much about them yet, but they promise to tell us a lot more," Kotliakov says.

Teams have stopped drilling at Vostok for fear of punching into Lake Vostok, a huge body of water locked so far beneath the ice sheet that it may hold more ancient organisms in cold storage.

That's not to say they will never see the light of day: Scientists from many nations are now debating the best way to probe the lake without contaminating it.

By Michael Milstein, Discovery Online News