Arctic sea ice melt leads to atmospheric new particle formation

Abstract

Atmospheric new particle formation (NPF) significantly influences climate by supplying new seeds for cloud condensation and brightness. Currently, there is a lack of understanding of whether and how marine biota emissions affect aerosol-cloud-climate feedbacks in the Arctic. Here we analyse a 11-year record of physical and chemical atmospheric measurements taken at Ny-Alesund, Svalbard. The temporal occurrence of NPF events in the polar marine boundary layer is quantified annually as 29%, with a peak of 81% during summer months. Air mass trajectory analysis and atmospheric nitrogen and sulphur tracers link these frequent NPF events to biogenic precursors released by open water and melting sea ice zones. The occurrence of NPF events across a full decade is anti-correlated with sea ice extent. New particles originating from open water and sea ice melt increase cloud condensation nuclei concentration background by ca. 20%, supporting a hitherto unaccounted biosphere-climate link through plankton, sea ice melt and low water clouds. Our results prompt to a better representation of biogenic aerosol sources in Arctic climate models.