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Place 06 · The North Pacific Garbage Patch · Chapter 3 of 7
The Fast Side and the Slow Side
In 1992 a shipping container full of bath toys burst open in the middle of the North Pacific, and 28,800 ducks, beavers, turtles and frogs became the most cheerful ocean experiment ever run.
About 15 minutes · 1 video · 1 live drift model · 2 quick activities
Start here
The gyre is lopsided
The water circling the hill does not go around at one speed. Off Japan, the Kuroshio is a warm, fast, narrow river in the sea; off California, the California Current is a cool, slow, wide drift. According to Webb’s textbook, the Kuroshio is around 15 times faster, 20 times narrower and 5 times deeper than the California Current, even though the same water has to pass along both sides.
Watch this
See it move
NASA Goddard — Perpetual Ocean. Three minutes of the world’s surface currents from a NASA computer model, drawn as glowing brushstrokes. It looks like a painting because the ocean really does move like this.
While you watch, look for
- Which edge of each ocean basin has the brightest, fastest, narrowest currents
- The swirling eddies that spin off the fast currents
- Something you did not expect. Hold onto it.
The short version
Three things going on here
The fast side
The Kuroshio races north
Along the western edge of the North Pacific, the Kuroshio carries warm tropical water north past Taiwan and Japan in a narrow, deep, fast jet; it is the Pacific’s version of the Gulf Stream. Western boundary currents like these are among the fastest ocean currents on Earth, reaching more than 2.5 m/s in places. The reason is Earth’s spin, whose effect on moving water changes with latitude, squeezing the return flow of every gyre against the western side of the basin: western intensification.
The slow side
The California Current drifts south
On the eastern side, the California Current spreads the same flow across a band hundreds of kilometers wide and ambles south along the coast, cool and slow; it is the current that flows past Monterey Bay’s upwelling coast from Place 02. Put the whole loop together and you get the North Pacific gyre: the Kuroshio north past Japan, the North Pacific Current east across the ocean, the California Current south, and the North Equatorial Current west again, south of Hawaii. Floating debris can ride it around for years.
The accidents
Shoes, ducks and a dock
In 1990 a ship lost tens of thousands of Nike shoes in the North Pacific, and in 1992 another lost 28,800 bath toys; oceanographers Curtis Ebbesmeyer and James Ingraham asked beachcombers where they washed up and used the finds to check a computer model of ocean currents. The first toys reached the coast near Sitka, Alaska, about ten months later. In 2011 the Tōhoku tsunami swept an estimated 5 million tons of debris into the Pacific, and by 2017 at least 289 living Japanese coastal species had ridden it to North America and Hawaii.
Photos: KJ Brix, Zip Cade, Alexey Demidov / Pexels
Play with it
Drop plastic in the sea and see where it goes
Plastic Adrift uses the tracks of thousands of real drifting buoys, followed by satellite since the late 1970s, to predict where floating plastic travels over ten years. Choose Forward, click the ocean just off Japan and watch it spread; then start again from just off California and compare.
Interactive model: Plastic Adrift by Erik van Sebille and colleagues (plasticadrift.org), based on data from the Global Drifter Program.
Two questions to answer while you are in there
- Which release point spreads out along the coast faster in the first year or two: Japan or California? Does that fit the fast western side and the slow eastern side?
- After ten years, where does most of the plastic from both starting points end up? Why there, and not on the nearest beach?
Try it yourself
Check yourself
Try it
Fast Side or Slow Side?
Eight quick calls about the currents that carry the trash around the North Pacific.
Try it · interactive
Drifter Race
Release two drifters, one in the Kuroshio and one in the California Current, and race them to compare the speed and width of the fast western and slow eastern sides of the gyre; then replay the 1992 bath-toy spill.
Open the Drifter Race in its own window (opens in a new tab).
Words you will hear
Four terms, that is all
Western intensification
Currents faster and narrower on basins' western sides
Western boundary current
Fast, narrow current along a basin's west edge
Kuroshio
Fast warm current flowing north past Japan
Drifter
Floating buoy tracked by satellite to follow currents
Check your understanding
Practice the whole chapter
Everything in this chapter, in eight quick questions. Retry as often as you like. Read the feedback on every answer, right or wrong, because that is where the learning is.
Practice
Practice: The Fast Side and the Slow Side
Eight questions covering the video, the three cards, the four terms and the interactive above.
If you want more
Go deeper
- Webb 9.4 — Western Intensification — LibreTexts · 6 minutes
- Our World Ocean 4.1 — Bottles, Drifters, and Floats — LibreTexts · 5 minutes
- Oceanography 101 (MiraCosta) 9.6 — Boundary Currents — LibreTexts · 4 minutes
Photo credits (Pexels): Andre Moura, Oleksiy Yeshtokyn,🌻🇺🇦🌻, KJ Brix, Zip Cade, Alexey Demidov.
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