Antarctic sea ice losses drive gains in benthic carbon drawdown

Abstract

2x105 tonnes of carbon per year since the 1980s. Annual production of bryozoans is median within wider Antarctic benthos [4], so upscaling to include other benthos (combined study species typically constitute ∼3% benthic biomass) suggests an increased drawdown of ∼2.9x106 tonnes of carbon per year. This drawdown could become sequestration because polar continental shelves are typically deeper than most modern iceberg scouring, bacterial breakdown rates are slow, and benthos is easily buried. To date, most sea-ice losses have been Arctic, so, if hyperboreal benthos shows a similar increase in drawdown, polar continental shelves would represent Earth's largest negative feedback to climate change.