In addition to the effects on the atmosphere, masses of microorganisms flushed into the sea will certainly challenge marine systems and could upset the oceans' delicate chemistry. [See sidebar: Loss of 'world's largest wetland' could tip ocean balance]
And scientists see evidence that the microbes are evolving inside the ice sheets, exchanging DNA and gaining new traits. While these cold-loving organisms appear to pose little threat to warm-blooded creatures, they could force out existing microbial populations, with unknown consequences. [See sidebar: Warming climate sets evolution within ice to high]
The frozen "bacteriasicles," as Louisiana State University microbiologist Brent Christner describes them, can emerge from the ice after hundreds of thousands of years poised to grow and divide when favorable conditions arise. Christner, an associate professor in the Department of Biological Sciences, has revived bacteria encased in 750,000-year-old ice.
"When we look in the oldest ice we can get our hands on, we still find there are cells living," he said.
It's a big deal, Christner added, because researchers don't understand how an organism can "sit for 750,000 years in some state of suspended animation like when Han Solo was put in carbonite."
Around since the Stone Age
It turns out that being immobilized in ice is actually a good way for microbes to preserve themselves. Inside those glaciers, they appear to be existing in a minimally-active state, maintaining their DNA and somehow repairing the damage incurred over time from radiation, oxidation and other harmful forces. They may be able to remain "frozen" like this almost indefinitely, according to Christner.
Being around since the Stone Age does take its toll on a body, however. The older the ice, Christner finds, the longer it takes the organism to revive.
The bugs in the ice are giving scientists an exciting opportunity to examine ancient genomes and learn about Earth's past climates from the organisms living in previous times of warming and cooling. "You kind of think of ice as a museum back in time, this window back into your past," said Christine Foreman, an associate research professor of microbial ecology at Montana State University who is examining microbes found in Antarctic ice deposited up to 60,000 years ago.
For Priscu, the fundamental question, at least in terms of paleoclimate, is whether different bacteria communities exist during glacial periods versus interglacial periods. "If we take our current warm period now, are the bacteria different than they were a million years ago?"
Priscu hopes to answer that question next winter, when he and an American research team drill into an ice stream below the West Antarctic Ice Sheet that may harbor descendants of microbes living on the continent when it began to freeze over more than 20 million years ago.
That effort is one of three underway to drill into long-buried Antarctic waterways and bring organisms sequestered under the ice into the light of modern day: In February, a Russian team pierced more than two miles of ice in remote east Antarctica to reach Lake Vostok, a body of water the size of Lake Erie that has been sealed off for 25 million years. And British scientists are drilling into a subglacial lake more than a mile below the continent's western surface.