Debris Headed to a Beach Near You? Sailors Track Tsunami's Destruction from Japan to US
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Within 12 hours of gaining the open ocean out of Tokyo Bay, bad weather was on us. Thirty knot winds, heavy seas and rain so hard visibility didn’t extend to the front of the ship. Conversations aboard considered the contingencies; tsunami debris present vs. small steel sailing ship steered in poor visibility. What are the limits of radar? How strong is the hull? To be safe, the watertight bulkhead door to the front of the ship remained closed at all times in case of a hull breach.
The ocean is big. There is no way to impress that fact upon someone who hasn’t crossed one. Statistics like the ocean covers 70% of the earth’s surface are meaningless to a population that on average ventures fewer than 40 miles from home, daily.
But when the math of the ocean’s size starts hitting the brain, finding flotsam in any quantity is alarming, especially when spotting garbage is at least a thousand times more common than seeing wildlife. The chief science officer, Dr. Marcus Eriksen of 5 Gyres, had arranged at-sea interviews with major news organizations about the voyage. Upon ‘finding’ the debris field, a theoretical place in space and time, perceived by much of the public and press to have an appearance of a contiguous mass, was where the major news organizations wanted their stories set. But most of them only wanted stories if we discovered exceptional debris like refrigerator trucks and severed appendages floated by shoes. Ordinary household effects like buckets, detergent bottles, and laundry baskets were ever present in the water, but distinguishing between regular pollution and tsunami pollution was difficult.
In fact, as part of the larger macro-debris studies while at sea, our crew participated in timed observations of the sea surface which involved two people sitting on the bow of the ship, one watching left, the other, right for an hour. The National Oceanic and Atmospheric Administration (NOAA) developed a protocol for the activity where observers record and classify everything that floats past. After gathering 41 hours of data, the expedition’s results found that 98% of marine debris out there is plastic, and was seen every 3.6 minutes traveling at an average of around six knots over 3,500 nautical miles. Every 60 nautical miles we deployed a surface trawl, too, to gather micro-plastic debris present. Each sample, from a swath of ocean 60 centimeters by 25, yielded a handful of photo-degraded plastic confetti. Yikes.
If one considers the average home’s inventory, anywhere in the world, the majority of objects aren’t necessarily of any intrinsic or aesthetic value; they’re just synthetic forms made for utility meant to be discarded after a couple of uses. A water bottle that finds its way to a watershed has the same effect of losing one in a tsunami, scientifically speaking. Positively identifying tsunami debris is easier for the rarer objects in our lives, like spare tires, Harley Davidson’s, wall or flooring material, propane tanks and boats—the things that are rarely, if ever, littered or fall out of an overflowing garbage can.
Such were the things we found that we positively identified as tsunami debris, some 1,500 miles east of Japan—almost at exactly the same day the dock section washed up in Oregon, thousands of miles farther east. What’s the explanation? Scientifically, different objects travel at different speeds, depending on how much sticks out of the water and is affected by wind. But to try to develop a simulation that accounts for wind sheer and predicts how two like objects will travel is almost an exercise in futility. The North Pacific Ocean as a mechanism isn’t a very well known scientific story; it’s a variation on a theme. As Dr. Curtis Ebbesmeyer, author of Flotsametrics, told me in an analogy speaking about how the North Pacific works, “After you sweep your floor, you know where some of the dust bunnies will gather again--like in the corners, but others will form in places you never expected.” This is how the ocean works, he explained.