How Microplastics are Changing the Oceans

Microplastics are changing the oceans, with millions of metric tons of plastic shedding trillions of pieces of plastic into our seas. They are harder to see than seabirds with stomachs full of plastic or sea turtles entangled in abandoned fishing nets, but just as concerning. Microplastics have infiltrated the entire marine ecosystem, from the sea surface to the seafloor, and these plastic particles are harming wildlife and disrupting critical ecological processes that regulate ocean health—and, in turn, the health of our planet.

In the oceans, sunlight, wind, waves, and other forms of weathering rapidly break plastic items up into microplastics and even smaller nanoplastics. Roughly 170 trillion plastic particles, weighing 2.3 million metric tons, now circulate the ocean’s surface waters alone. Scientists estimate an additional 11 million metric tons of plastic has been deposited on the seafloor, shedding an unknown amount of microplastic that mixes with ocean waters and sediments. An unknown amount of plastic and plastic particles permeate the middle ocean layers.

Scientists are just beginning to uncover the full extent of the damage caused by plastic pollution in the oceans, but it is already known to be harmful. Microplastics have been found to cause serious health problems and their consumption is linked to mortality in corals, fish, marine mammals, seabirds, sea turtles, zooplankton, and other ocean creatures. More broadly, microplastics are interfering with the ocean’s biogeochemistry—the web of biological, chemical, and geological interactions that drive vital Earth cycles, sustain marine ecosystems, and regulate the climate. These disruptions carry serious implications not only for marine life, but also for humans, as all life on Earth depends upon a healthy ocean.