Moby-Duck by Donovan Hohn Read Free Book Online Page A

containers tall, tall as a four-story townhouse, would have been more horizontal than vertical. Perhaps Dr. Ebbesmeyer would like to have a peek at the logbook, the captain discreetly suggested. He’d already opened it to January 10, 1992. There were the coordinates, the magic coordinates.

THE GREAT PACIFIC GARBAGE PATCH
    OSCURS could now reconstruct, or “hindcast,” the routes the toys had traveled, producing a map of erratic trajectories that appeared to have been hand-drawn by a cartographer with palsy. Beginning at the scattered coordinates where beachcombers had reported finding toys, the lines wiggled west, converging at the point of origin: 44.7°N, 178.1°E, south of the Aleutians, near the international date line, where farthest west and farthest east meet. The data that Ebbesmeyer’s beachcombers had gathered also allowed NOAA’s James Ingraham to fine-tune the computer model, adjusting for such coefficients as “windage” (an object with a tall profile will sail before the wind as well as drift on a current).
    At first, before they’d sprung leaks and taken on water, the toys rode high, skating across the Gulf of Alaska at an average rate of seven miles per day, almost twice as fast as the currents they were traveling. Among other things, the simulation revealed that in 1992 those currents had shifted to the north as a consequence of El Niño. If the toys had fallen overboard at the exact same spot just two years earlier, according to OSCURS, they would have taken a southerly route instead of a northerly one, ending up in the vicinity of Hawaii. In 1961, they would have drifted along the California coast.
    Though with far less certainty, OSCURS could forecast as well as hindcast, and in this respect, Ebbesmeyer and Ingraham were like meteorologists of the waves. Because the weather of the ocean usually changes more slowly than the weather of the skies, they were also like clairvoyants. OSCURS was their crystal ball.
    By simulating long-term mean surface geostrophic currents (those surface currents that flow steadily and enduringly, though not immutably, like rivers in the sea) as well as surface-mixed-layer currents that are functions of wind speed and direction (those currents that change almost as quickly as the skies), OSCURS could project the trajectories of the toys well into the future. According to the simulator’s predictions, some of the animals that remained afloat would eventually drift south, where they would either collide with the coast of Hawaii in March of 1997 or, more likely, get sucked into the North Pacific Subtropical Gyre.
    â€œ Gyre is a fancy word for a current in a bowl of soup,” Ebbesmeyer likes to say. “You stir your soup, it goes around a few seconds.” The thermodynamic circulation of air, which we experience as wind, is like a giant spoon that never stops stirring. To make Ebbesmeyer’s analogy more accurate still, you’d have to set that bowl of soup aspin on a lazy Susan, since the earth’s rotation exerts a subtle yet profound influence on the movements of both water and air, an influence known to physical oceanographers as the Coriolis force. The Coriolis force explains why currents on the western edges of ocean basins are stronger than those along their eastern edges—why the Gulf Stream, for instance, is so much stronger than the Canary Current that flows south along Africa’s Atlantic coast.
    Comprising four separate arcs—the easterly North Pacific Drift, the southerly California Current, the westerly North Equatorial Current, and the northerly Kuroshio (the Pacific’s equivalent of the Gulf Stream)—the North Pacific Subtropical Gyre revolves between the coasts of North America and Asia, from Washington State to Mexico to Japan and back again. 1 Some of the toys, OSCURS predicted, would eventually escape the gyre’s orbit, spin off toward the Indian Ocean, and circumnavigate the