Monterey Bay beachcombers, mark your calendars for next summer. That’s when the first of the debris from Japan’s March 11 earthquake and tsunami might begin washing up on our shores.


Or not. Experts have different opinions about what path the debris will take, and at what pace – so their predictions come with an ocean of salt.


Nikolai Maximenko of the University of Hawaii’s International Pacific Research Center estimates the debris will reach the Midway Islands in six months, the main Hawaiian Islands in two years and the North American West Coast in about three years. [Check out his simulation of the debris movement here.] Most of it will then likely recirculate southward to the North Pacific Garbage Patch, a toilet-bowl-like gyre where ocean litter accumulates.


“Fortunately, California still has time,” he says.


California has something else going for it: coastal upwelling, in which winds push water away from the coast. Maximenko expects California beaches to remain relatively clean while massive debris washes up north of Portland. 


Possibly, though not probably, some of that debris will be radioactive. By the time contaminated water was released from the Fukushima Daiichi nuclear power plant in early April, Maximenko says, most of the tsunami wreckage had already blown offshore.


Jeffrey Paduan, chair of the Naval Postgraduate School’s Oceanography Department in Monterey, predicts the debris is heading toward our coast at speeds of less than 6 miles per day. The movement of specific materials varies by windage, the affect of wind drag on flotsam. 


“I wouldn’t expect to see things until next winter or the one after,” he says. “The currents between here and there are pretty weak, generally.” 


He agrees with Maximenko that most radioactivity will be diluted to the point of harmlessness by the time it arrives here, with the possible exception of tightly sealed materials.


Oceanographer Curtis Ebbesmeyer, co-author of Flotsametrics and the Floating World, is modeling the movement of tsunami debris at beachcombersalert.blogspot.com. He predicts the debris will hit the West Coast (particularly Oregon, Washington and British Colombia) in spring 2013.


“Imagine the city of Monterey put through the shredder,” he says. “What would you expect to see on the beach?”


Ebbesmeyer describes a tsunami debris field about the size and shape of California, with the long edge moving 5-7 miles per day across the Pacific. He guesses the debris includes cedar wood, ceramic pots, fishing boats, perhaps even safes and other valuables. Beachgoers may also come across disembodied feet in sneakers, which he says should be reported to the police in hopes of returning the remains to family members.


“There’s gonna be some body parts,” he says. “Beachcombing isn’t always fun and games.”