Waves can carry ocean debris over long distances due to the movement of water and ocean currents. These forces can propel debris across the ocean and move them thousands of kilometers.
The wind is the main engine that drives the waves across the oceans. Typically, the stronger and longer it blows, the more energy it imparts to the water's surface, creating increasingly larger waves. These waves capture plastics, debris, and other floating objects, all of which are transported thousands of kilometers thanks to the energy transferred through the friction between air and water. This is called wind drift, it's a bit like when the wind pushes a dead leaf across a lake, but on a much larger scale! These movements allow waste from one continent to end up on beaches located on the other side of the world.
Ocean debris can travel very far thanks to ocean currents, which are like large underwater rivers that mix huge amounts of water across the oceans. Among the most well-known are the Gulf Stream, which crosses the Atlantic from the Gulf of Mexico to Western Europe, and the Kuroshio Current in the Pacific, flowing from the Japanese coasts to North America. These currents are driven by different water densities, created by differences in temperature and salinity. They are also called thermohaline currents, and they are capable of transporting anything that floats or drifts over impressive distances, sometimes several thousand kilometers. Thanks to these true underwater conveyor belts, a plastic bottle thrown on a beach in Florida can end up somewhere on a European coast after several months or years.
The swell, this regular undulating movement on the surface of the ocean, can carry debris over incredible distances. Unlike waves directly created by local wind, swells form far from where they are observed. Essentially, a storm or strong wind can trigger a swell at a specific location, which will travel thousands of kilometers before completely dissipating. Floating objects, such as plastics or pieces of wood, then get caught up in this repetitive back-and-forth movement. As a result, even without particular wind, this debris follows this slow, regular motion and eventually ends up far from its original starting point. It's like a kind of free and long-distance marine carpool for waste.
Severe storms or hurricanes act like real machines for moving floating objects. With their powerful winds and huge waves, they can quickly push debris to new regions, sometimes thousands of kilometers away. For example, after the 2011 tsunami in Japan, currents and violent storms carried all sorts of debris to North America for several years. These extreme weather events stir the ocean surface intensely and allow materials that are normally trapped to be redistributed over very large distances.
Tides work somewhat like a great breath of the oceans. When the tide rises, the water moves towards the shore and carries with it floating debris. Once the tide has receded, this debris can resume its journey out to sea or to another part of the coastline depending on the prevailing current direction. This regular and powerful up-and-down movement thus facilitates the dispersion of waste over hundreds or even thousands of kilometers. Particularly strong tides, or spring tides, can push objects that initially seemed stranded on the beaches even further away.
Did you know? Microplastics, which result from the slow decomposition of plastic waste carried by ocean currents, are now found even in the most remote ocean regions like Antarctica!
Did you know? The "Great Pacific Garbage Patch," also known as the "plastic continent," is a large area of ocean waste accumulation trapped by currents, covering an area equivalent to three times the size of France!
Did you know? Amazing objects such as LEGO, sports balls, and even plastic animals regularly wash up on remote shores due to long-distance transport by ocean currents and waves.
Did you know? In 1992, nearly 29,000 plastic bath toys, including yellow ducks, were lost in the Pacific Ocean during a storm, allowing scientists to improve their understanding of ocean currents by observing their paths across multiple oceans!
The majority of marine debris transported over long distances consists of plastics, due to their lightweight, buoyancy, and resistance to degradation. Single-use plastics, bottles, and lost or abandoned fishing nets represent the main categories of drifting ocean waste.
Ocean debris carried by waves can cause serious harm to marine wildlife through accidental ingestion, choking, or entanglement. They disrupt natural habitats, alter ecological balance, and introduce toxic substances into marine ecosystems.
Although current technologies, such as numerical models of ocean circulation, allow for a general estimation of debris trajectories, it remains difficult to make precise predictions. Local variations, unforeseen weather conditions, and multiple interactions significantly influence their path.
Yes, this is known as the phenomenon of biological rafting. Many marine species can cling to floating debris and thus travel considerable distances. This involuntary transport can lead to biological invasions, threatening local biodiversity on other continents.
Some ocean debris can drift for several months, or even years, depending on the prevailing currents, wind strength, and the nature of the material (density, buoyancy, degradation). It is not uncommon for objects to travel thousands of kilometers before reaching a beach.
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