Go with the flow. For some people, this is a life philosophy; for oceanographers, it describes the very dynamics of our global ocean.
Early seafaring cultures knew of dependable ocean currents that moved their craft swiftly across the sea, like conveyor belts. The Polynesians were among the first to develop oceanographic maps. Made from shells and sticks of bamboo, these stick charts enabled them to deftly navigate Pacific currents.
Mapped in 1762 and named by Benjamin Franklin, the Gulf Stream is the Atlantic Ocean’s best-known current. Functioning like a gigantic river, it carries a greater volume of water than all of the world’s freshwater rivers combined.
Starting with the Gulf of Mexico’s loop current, the stream flows around the southern tip of the Florida peninsula and runs up the Eastern Seaboard. Here in Maryland, at Ocean City, Gulf Stream eddies make for great sport fishing. It then speeds up the coast into New England, finally taking a right at Cape Cod to cross the Atlantic to Europe, influencing the climate of every landmass it passes.
For example, Penzance, on England’s southern tip, is warmer than any other area at that latitude thanks to the Gulf Stream's tropical effect. In spite of its location, its environment even supports palm trees!
But the map of global ocean currents wasn't drawn with precision until fairly recent times. And that was literally a windfall, involving a now-famous shipment of rubber duckies.
In 1992, a ship on its way from Hong Kong to the United States was carrying, among other things, a container of bath toys. The container was accidentally lost overboard in the middle of the Pacific, where it broke open and 28,000 plastic ducks were let loose to sail (or more accurately, bob) across the high seas.
Oceanographers call this fleet the "Friendly Floatees," and they became a boon to science, functioning as current-tracking mini-buoys for years.
Among other things, the duckies provided proof of the existence of the North Pacific Gyre, where 2,000 ducks still float, locked in a loop with other plastics from all over the world in the Great Pacific Garbage Patch.
In 2007, a duckie appeared on a beach in France, marking a 15-year, 12,000-mile journey around the globe, from the Pacific to the Atlantic. Another was found trapped in Arctic ice. The message from the duckies is clear: Our one world ocean is truly interconnected.
While the Gulf Stream and the North Pacific Gyre are composed of surface currents driven by wind and the Earth's rotation, there are also great, moving rivers in the deep ocean.
Driven by temperature and salinity gradients, the thermohaline conveyor—called thermo for temperature and haline for salt—begins as the warm Gulf Steam cools in the northern Norwegian Sea. Ice forms, taking with it freshwater and leaving behind dense, salty, cold water that sinks to the bottom of the ocean.
Amazingly, this global ocean conveyor carries a volume of water almost 5,000 times greater than Niagara Falls, transporting 20 million cubic meters of water per second. That's equivalent to half a million Olympic-sized swimming pools every minute.
This global circulation system slowly mixes and churns all of the planet’s seawater in a process that can take a thousand years.
Scientists believe climate change may already be impacting this important system and, by extension, the nutrient distribution that is the foundation of the world's fisheries, underscoring again the importance of mitigating the effects of global climate change.