Seven years into the North Pacific garbage patch: legacy plastic fragments rising disproportionally faster than larger floating objects

Abstract

The North Pacific garbage patch has accumulated floating plastic pollution for several decades. The Ocean Cleanup, a not-for-profit organization that works to retrieve this floating plastic, has conducted systematic surveys in the North Pacific Subtropical Gyre since 2015. The dataset, now spanning seven years, includes the deployment of trawls of varying sizes and the collection of aerial imagery. Here, we report a synthesis of these measurements and highlight an unexpected rise in mass concentration of plastic fragments (0.5–50 mm, from 2.9 kg km−2 in 2015 to 14.2 kg km−2 in 2022), increasing at a faster rate than that of larger items (>50 mm). With a mass balance model, we show that a substantial fraction of this material (74%–96%) is new to the region and does not result from the degradation of larger items that were already present in these waters seven years ago. Instead, we hypothesise it is the signature of the degradation and transport processes of legacy floating plastic pollution left accumulated in the global marine environment for the past decades.