Will the fossil record show what defines our times?
Just as we dig up evidence of what we call the Stone, Bronze and Iron Ages, when our descendants look back at our era, they may well sum us up with one word: Plastic.
In a study from Scripps Institution of Oceanography, microplastics biologist Jennifer Brandon and colleagues used coring equipment to collect seafloor sediment from the Santa Barbara Basin. With these sedimentary layers recording a history of the area, much like tree rings, they found an exponential increase in plastic fragments since the end of World War II. In fact, comparing 1945 to 2010, when the samples were collected, researchers found evidence of 10 times as much plastic in the basin.
The sharp increase matches a rise in the rate of plastic production worldwide, as well as a surge in California’s coastal population. The research team noted that since the 1940s, the amount of microscopic plastics found in sediment has doubled about every 15 years.
Brandon says the discovery supports the idea of plastic accumulation being a defining signifier of the Anthropocene, a proposed new geological epoch marked by humanity’s effect on Earth. Specifically, the rise of plastics beginning in 1945 could serve as a marker for a time period within the Anthropocene that scientists have labeled “the Great Acceleration.”
“This study shows that our plastic production is being almost perfectly copied in our sedimentary record. Our love of plastic is actually being left behind in our fossil record,” says Brandon, whose work appeared in the journal Science Advances in September.
The work is the latest of several studies to document the pervasiveness of plastic in the oceans. Ten years after Scripps researchers made the first estimate of plastic accumulation on the surface ocean near Hawaii, this June another Scripps study off the coast of Monterey, Calif., found microplastics at depths of 1,000 meters (3,300 feet) beneath the surface. In April, an explorer visiting the deepest part of the ocean, the Mariana Trench in the western Pacific Ocean, found evidence of plastic bags at the seafloor.
Researchers at Scripps and the Jacobs School of Engineering have begun collaborating to develop technology that can detect and quantify plastic microfibers in water samples as a first step toward quantifying the presence in the world oceans. They are also partnering with industry to identify possible avenues to limit plastic pollution and develop remediation strategies.
“Our study may have found the sediment record shows a steep exponential increase in plastics,” Brandon says, “but if we get creative with limiting plastic use and with remediation strategies, we can bend that curve for future generations.”