Global distribution and cleanup opportunities for macro ocean litter: a quarter century of accumulation dynamics under windage effects

Abstract

Ocean litter is of growing global concern, and its impacts on marine environments and ecosystems are expected to increase further this century. From a management perspective, natural drifting of macro ocean litter to or near the coast may have a relatively easier opportunity to be cleaned up directly from land, which then helps eliminate litter sufficiently and reduces the associated societal costs. However, quantitative descriptions both of the potential arrival areas of accumulation and of the cumulative impacts of ocean litter and services are lacking. The wind is critical to restructuring litter distributions in locations greatly different from those within the gyres where litter is typically found, prompting strong concerns regarding previously ignored areas, especially the equatorial zone and northern polar regions. As the windage increases, litter is transported across oceans, and polar oceans would become a litter sink instead of a source when litter is simulated to originate from both offshore and coastal areas. Different proportions of offshore- and coastal-source litter exhibit different terminal configurations, including floating offshore, floating near the coast and washed ashore. Notably, depending on windage, 78.4%–94.0% and 54.1%–56.1% offshore- and coastal-source litter continue moving in the oceans. Furthermore, important consequences associated with global marine biodiversity priority areas and litter accumulation are identified, as are substantial increases in influences on phytoplankton biomass with increasing windage. The results not only improve our understandings of macro ocean litter accumulation but also reveal opportunities for proactive prevention and planning of cleanup efforts with relatively low costs regardless of the ocean litter’s offshore or coastal origins and can provide support for regional-to-global actions and policies addressing the contemporary impacts of macro ocean litter on environments.