Environment / Global Warming

Not many ships venture into the Drake Passage, 500 miles of heave and blow between the fjords of southern Chile and the tip of the Antarctic Peninsula. At these latitudes, there is nothing but icy cold ocean, 360 degrees of it. With no landmass to break the wind's fetch, a ship can expect to run into waves that are two, three, even five stories high. Sailing crews consider these the most treacherous seas on the planet.

This afternoon, the Drake is living up to its reputation. As near-hurricane-force winds slam growing swells into the research vessel Nathaniel B. Palmer, scientists below deck scurry to lash down computer terminals and plaster lab equipment with bubble wrap. Off the starboard side, a cavalcade of hulking waves begins to line up, each ready to take a nice swing at the ship. Deck hands pelted by frozen sea spray and snow stagger like drunks. The barrage of these ice bullets comes in horizontal, so fierce it’s impossible to keep my eyes open for more than a moment. But in that moment, I have the unfortunate luck to glimpse the frenzied ocean over my shoulder. I have read that people drown in seas like these because there’s so much wind-whipped water in the air that even if you can keep your head above the surface, you cannot draw a breath. Of course, if unprotected by a suit, you’ll lose consciousness in seas this cold after one and a half minutes anyway.

On the bridge deck, Second Officer Paul Jarkiewicz tells stories. He recalls a brutish wave that once hurled the entire chart table out of its mounts and down the hall. At one time, the marine projects coordinator was sighted on the aft deck, clinging to equipment, his legs blown straight out behind him like a flag in the wind. Eventually, of course, his conversation turns to the fear that lurks in the consciousness of every sailor who ventures into these waters: the rogue wave scenario. In a storm at sea, wind-driven waves line up perpendicular to the wind’s direction. The helmsman can steer the ship to take the waves head on, the bow pointed right at the heart of the wind. Or he can maneuver the ship to take the waves “broad on the bow,” at a 45-degree angle. Ships are designed to withstand seas taken that way. But one in every 10,000 waves or so doesn’t get the message to line up with the others. That so-called rogue wave comes at the ship from a completely unexpected direction, from the side or from aft. “Rogue wave comes along and breaks a ship’s back,” says Jarkiewicz, fiddling with his radar controls. “She’s gone in a matter of minutes. And so are you.”

So what kind of science is done at the risk of having men and women swept overboard and a $TK-million ship lost at sea? What could be as important as the lives of the 60 people on the Nathaniel B. Palmer? In short, the future of the planet. The one we live on. The ultimate goal of this trip is to gather clues about global warming. But the more immediate goal concerns a regional warming trend in Antarctica. Nobody knows exactly what this trend means for the rest of the world, but the western side of the Antarctic Peninsula is warming up faster than any place on earth. Comparisons of climate records from just a half-century ago show that temperatures here have risen, on average, 21/2 to 3 degrees Celsius. Between 1966 and 1989, most of the Wordie Ice Shelf, 502 square miles, disappeared. And over the past 18 months, two of the peninsula’s largest ice shelves, the Larsen B and the Wilkins, have lost nearly 1,100 square miles of their total area, a sheet of ice about the size of Rhode IslandCK. That’s five to ten times the average annual loss over the past 10 years. At that rate, much of the Wilkins ice shelf will be gone in a few years, says glaciologist Ted Scambos of the University of Colorado at Boulder. “Nobody expected it to happen this fast.”

Although very few scientists still deny global warming is upon us, no one yet knows how much of it—if any of it—could be due to a recurring natural temperature cycle. The answers to that crucial question lie in the ancient past. And to find those answers, one must go back and look at what was happening with temperatures hundreds to thousands of years ago. One way to do that is by studying long-buried, centuries-old marine sediment: mud from the ocean floor.

And so a team of marine sediment experts has set up shop on the Nathaniel B. Palmer, hoping to sink great hollow cores deep into the ocean off Antarctica. It is a pilgrimage some of them have been making for over a decade. Nothing about this kind of research is easy—not the getting there, not the doing. Sponsored by the National Science Foundation’s Office of Polar Programs, the scientists will spend two weeks on board. If all goes well, they will haul up 10-, 20-, and 80-foot columns of green muck. It will tell them the story they’re looking for: the story of ancient climates. For the ocean floor is a record, an eons-old accumulation of whatever has sunk down through the water to the bottom of the sea.

What sinks to the ocean floor depends in part on how warm the climate is. When it’s cold enough to form ice shelves that extend over the Antarctic land mass and into the ocean, much of what drops to the seafloor is sand and gravel that the glacier has picked up on its slow march from the continent’s ice cap. Sandy ocean sediment is associated with ice cover, and when you find it somewhere far from the ice edge, you know that at some point the ice reached that site. When the weather warms and no ice sits upon the seas, the sediment on the ocean floor is mainly organic: remains of plankton and diatoms. By reading the ups and downs of organic versus nonorganic sediment in a core, sedimentologists can follow the retreats and advances of ice over the past 20,000 years. So far, ice cores from Greenland and marine sediment cores from Antarctica show that a notable warming period occurred from 3,000 to 8,000 years ago. Nobody knows for sure why the warming occurred, but researchers suspect that a slight wobble in Earth’s orbit could be responsible. That wobble could have shifted Earth’s position, which might have altered patterns of ocean circulation and climate.

Researchers are more certain about what’s driving the warming trend today. Says Colgate University marine geologist Amy Leventer, one of the chief scientists on this voyage, “I think it’s clear that some portion is due to the sun. But I also think it’s undoubtable that some percentage is due to man.”

Yesterday’s storm has moved on, leaving behind an unearthly stillness broken only by the calls of snow petrels and the engine’s throaty hum. We have arrived at the mouth of the Muller Ice Shelf, near Lallemand Fjord. For those who picture Antarctica as a monotony of whites and grays, Lallemand Fjord is an awakening. The icebergs crowding the ship this morning are infused with a paint store panoply of blues, many of them arrestingly unnatural, like the bright, blaring blues of mouthwashes and toilet bowl cleaners. It is not merely the variety of hues that dazzles, but the intensity. The color appears to come from within, like the glow in a smoldering piece of coal. It’s a neat optical trick: As ice is compressed over time, it becomes easier for light to pass through it. Pretty much everyone is out on deck, looking at the ice.

For more about the Nathaniel