Behold the Plastic Age: synthetic fibres found in fossil record

GEOLOGISTS could one day determine the age of rocks by measuring the amount of plastic found in sediments, after researchers discovered rising volumes of waste are being preserved in the fossil record.

Oceanographers found that the number of plastic fragments preserved in sediments off the US Californian coast has been increasing exponentially since the end of World War II, matching increases in plastic production and local population growth.

Studying a core sample of sediments from the last 200 years, the team found that from the 1940s the volume of microplastics doubles about every 15 years. Close to 90% of the particles in the sediments were synthetic clothes fibres. The researchers warn that as coastal populations increase along with the production of synthetic clothing, fibres flowing into the sea via wastewater plants are becoming a larger concern.

“This study shows that our plastic production is being almost perfectly copied in our sedimentary record,” said Jennifer Brandon, lead author of the study and microplastics biologist at the Scripps Institution of Oceanography. “Our love of plastic is actually being left behind in our fossil record.”

Brandon said this discovery supports the idea of using plastic accumulation to define the Anthropocene, a proposed new geological epoch marked by humanity’s effect on the planet.

The study did not analyse the potential effects the plastics could be having on marine life, but noted previous research showing that the ingestion of plastics by marine life can cause physical damage that reverberates through the food chain.

A 2015 paper published in Science estimated that approximately 8m t of plastic enters the oceans each year, suggesting that by 2025 they will contain 250m t of plastic, 1 t for every 3 t of fish. The depth of the problem was thrown into stark relief in April, when an explorer visiting the Mariana Trench found that a plastic bag and sweet wrappers had already beaten him to the deepest point of the world’s oceans.

In January, companies throughout the plastics supply chain, including BASF and Dow Chemical, formed an alliance focussed on tackling plastic waste in the oceans.