It's a common sight for the crew of the Coast Guard cutter Polar Sea, breaking the summer ice to the American Base at McMurdo. What's unusual this year, says Capt. Gerald Davis, is the weather.
"This year was an unusual year," Davis says. "We had an awful lot of ice to break through -- about 31 feet -- to create this channel into McMurdo. . .Previous years seem to be a little milder than they were. There's definitely a cycle."
Scientists' say it was last year's El Nino that disrupted Antarctic weather. One researcher says El Nino may have very close ties to the continent. He noticed that when air pressure suddenly drops at the South Pole, an El Nino soon pops up elsewhere. The pressure drop may be the signal El Nino is coming.
"It could be the trigger," says Charles Stearns of the University of Wisconsin.
National Science Foundation researchers working at remote field camps are looking into Antarctica's role in global climate change. There is special interest in the stability of the Brazil-sized West Antarctic Ice Sheet. Its melting or collapse could cause catastrophic coastal flooding worldwide.
Scientist Joan Fitzpatrick says such an event would raise sea levels by five meters, putting U.S. cities like New Orleans or Malibu underwater. However extreme that may sound, Fitzpatrick is not among the doomsayers.
A new NASA computer model shows that over the past 20,000 years, the ice sheet has already lost two-thirds of its size. It's widely believed any new melting would occur over several centuries. However, what has surprised researchers is how quickly a new meltdown could start -- within just four years.
"Major climate change can be accomplished in a short period of time -- over the period of time it takes you to get through college in some cases," Fitzpatrick says.
Researchers know this from what the ice records tell them.
Within the ice walls of a carved-out storeroom, 20 feet beneath the surface of the researcher's base, lies the climate history of the West Antarctic Ice Sheet. Hundreds of ice cores are housed there, each one tens of thousands of years old. Scientists hope they reveal as much about the future of global weather patterns as they do about the past.
"We can get a good sequential, chronological record every year preserved in the ice, much like tree rings," says researcher Gregg Lamorey.
At the Siple Dome drill site, researchers have been retrieving ice cores from a hole 3,000 feet deep. Each core contains trapped air bubbles from ancient atmospheres.
"At the bottom, we calculate the ice is 80,000 years old," Lamorey says.
Sometimes the brittle samples shatter at the surface, but each piece ilike a page from the past, revealing temperatures, snow fall amounts, even wind direction. It is Fitzpatrick's job to search for parallels to what we see now.
"We're trying to pull a record out of the past in order to enable us to predict the future of climate change," she says.
Five hundred miles away in Antarctica's Dry Valleys, researchers are taking a close look at some actual changes occurring right now: melting glaciers. This year the water runoff is six times higher than normal, and part of a trend.
"That's not going out on a limb to say the past thirty years have been warmer," says hydrologist Diane McKnight.
McKnight says the finding is one small piece of the climate change puzzle. It's a puzzle that includes retreating glaciers and thinning sea ice in the Northern Hemisphere, and that other weather wildcard, El Nino.
"There isn't really ever a smoking gun, but many pieces of evidence coming together" she explains.
If the climate is getting warmer, say the scientists, this is where we will likely see the evidence first -- at the bottom of the world, at the edge of the ice -- the edge of change.
Reported By Jerry Bowen