Scientists flock to rubber duckies

Files/The Columbian

Challenged to probe under Greenland’s glaciers, NASA robotics expert Dr. Alberto Behar wondered what mechanism might endure subzero cold, the pressure of mile-thick ice and currents that sometimes exceed the flow rate of Niagara Falls. It was a daunting engineering proposition, even for someone experienced in conceiving robot explorers suitable for Mars and the moons of Jupiter.

Worried about climate change, many researchers are eager to learn how rising temperatures may be undermining Greenland’s ice cap, where, according to recent satellite measurements, glaciers are melting much faster than expected. Should Greenland’s 2.17 million square miles of ice ever melt completely, the water could raise sea level worldwide by 24 feet, swamping coastal cities that are home to millions of people.

As Behar at the Jet Propulsion Laboratory soon discovered, though, there isn’t much money for global warming experiments in Greenland.

Unfazed, he thought of one device that might survive such extremes at a cost his field expedition could readily afford — a two-dollar rubber duck.

Consequently, Behar and his colleagues at the University of Colorado this past August released 90 yellow rubber ducks into the melt water flowing down a chasm in the largest of Greenland’s 200 glaciers — the Jakobshavn Isbrae — which has been thinning rapidly since 1997. Each duck was imprinted with an e-mail address and, in three languages, the offer of a reward. If all goes well, Behar hopes that one day they will emerge 30 miles or so away at the glacier’s edge in the open water of Disko Bay near Ilulissat, bobbing brightly amid the icebergs north of the Arctic Circle, each one a significant clue to just how warming temperatures may speed the glacier’s slide to the sea.

In an era of billion-dollar space telescopes, gene machines and city-size particle accelerators, some scientists just have to make do with tub toys. From Greenland’s glaciers to the boundless Pacific main, researchers are tracking thousands of rubber ducks, frogs, beer bottles and wooden tops set adrift around the world to solve critical questions of oceanography, glaciology and global warming.

Researchers call it flotsam science.

As a scholarly discipline, it is perennially impoverished. Its only professional journal is a newsletter with a circulation of 600 called The Beachcombers Alert, published by retired oceanographer Dr. Curtis Ebbesmeyer in Seattle. More than anyone, Ebbesmeyer turned every beachcomber’s passion for sea-swept debris into a research tool by establishing an international network to gather traceable flotsam, such as Behar’s yellow ducks.

Indeed, it was a shipment of such bath tub toys washed overboard in the Pacific during a 1992 storm that accidentally launched this unusual field.

Each of the 28,200 plastic ducks, turtles and frogs that spilled from the ill-fated cargo container was stamped with a unique manufacturing code. As they washed ashore — sometimes thousands of miles from the original spillage — scientists soon realized they could trace the toys back to the launch point, documenting previously unsuspected ocean currents.

In the years since, Ebbesmeyer and his colleagues have tracked flotillas of floating hockey gloves, sodden sneakers, Guinness bottles, Japanese tops and New England lobster pot tags. All were labeled with some unique identifier that, in the serendipity of science, turned them from trash into data points charting vast, circular ocean gyres.

These global conveyor belts swept some of the tub toys from the 1992 spill through the Bering Strait into the Arctic Ocean, where the pack ice carried them over the North Pole into the North Atlantic Ocean, said Ebbesmeyer. Eleven years later in 2003, one of the plastic ducks turned up in Maine, while one of the plastic frogs washed up in Scotland, more than 7,000 miles from where it started.

Ebbesmeyer likes to call his research endeavor, documented last year in the American Geophysical Union’s journal, Eos, “accidental oceanography.”

Based on his experience, the NASA researchers ought to expect their yellow ducks to turn up where they least expect, perhaps decades from now. “These ducks last and last far beyond what anybody thinks,” he says. “They keep going round and round the ocean.”

While Behar at JPL was ordering his toy ducks earlier this year, glaciologist Sarah Das at the Woods Hole Oceanographic Institution in Massachusetts was looking for an inexpensive way to find out more about the water under the same Greenland glacier. She has been monitoring the drainage from the hundreds of melt-water lakes that dot the ice cap in high summer, some of them two or three miles across and more than 60 feet deep.

Last April, Das and her colleagues reported in the journal Science that they’d seen one large glacial lake drain in 90 minutes through a fracture that split the ice 980 meters down to bedrock. “If you calculate the volume, of water, it actually exceeds the flow over Niagara Falls,” she says. Scientists suspect these sub-glacial floods lubricate the bedrock under the ice sheets of Greenland and Antarctica, like a water slide, and accelerate the rate at which glaciers flow to the sea and break apart.

Das first thought to throw 10,000 elastic bouncy balls into one such fissure in the hope the balls would be washed under the ice and out to sea 25 miles away. After consulting the manufacturer, she decided such toys were too buoyant and would be trapped in the crevasses. She settled instead on the idea of pouring a nontoxic red dye into the melt water. “We guessed the dye might come out in the bay half a day later or maybe, if it was taking a really tortuous path, half a week,” Das says.

For a week in July, her students cruised back and forth across Disko Bay, trailing through the water a sensor able to detect microscopic traces of the fluorescent chemical. They never detected the dye.

As researchers learn more about the mechanics of Greenland’s glaciers, they are becoming convinced that, by itself, the sub-surface water slide created by so much melting ice may be a short-lived seasonal effect, says University of Washington polar scientist Ian Joughin. The glaciers speed up in the summer but slow down in the fall. If that’s true, there may be little risk the ice sheet will collapse as some scientists recently feared — at least not for the foreseeable future. Every year since 1979, however, the melt zone has reached deeper inland and further up the sloping ice cap.

Meanwhile, Behar seeks his wayward flock, submerged in currents of climate change. In a separate experiment, he tossed into the melt water a small metal tube stuffed with sensors, including a satellite modem. It, too, has yet to turn up.

“Right now, we just see the water going into a big hole,” says Behar. “We have no idea what it is like under there.”