Author(s)

A. J. Gabric, B. Qu, P. Matrai & A. C. Hirst

Abstract

Tropospheric aerosol particles constitute one of the largest uncertainties in model projections of the climate change. The major natural source of sulphur aerosols in remote marine atmospheres is dimethylsulphide (DMS), which is ubiquitous in the world’s oceans and synthesised by phytoplankton. Climate models point to significant future changes in sea-ice cover in the Arctic Ocean that may have consequences for primary production, and the sea-to-air flux of a number of biogenic compounds, including DMS. In this paper we discuss the impact of warming on the future production of DMS in the Arctic Ocean. A DMS production model has been calibrated to contemporary climate conditions using satellite ocean colour data (SeaWiFS). The CSIRO MK 2 climate model is used to force the DMS model under enhanced greenhouse climate conditions. Significant decreases in sea ice cover (by 18.5% annually and 61% in summer-autumn), increases of mean annual sea surface temperature (SST) by 1 °C and a decrease of mixed layer depth (MLD) by 13% annually, is predicted to lead to annual DMS flux increases of more than 100% (from 131.7 to 270.6 µmole m -2 ) by the time of equivalent CO2 tripling (2080). This is likely to have major consequences for summer sulphate aerosol concentrations in the Arctic region. Keywords: climate change, feedbacks, Arctic, dimethylsulphide (DMS), dimethylsulphoniopropionate (DMSP), mixed layer depth (MLD), ice algae. 1 Introduction One of the strongest high-latitude climate feedbacks is thought to be the ice– albedo mechanism, in which a positive temperature perturbation will melt sea

Keywords

climate change, feedbacks, Arctic, dimethylsulphide (DMS), dimethylsulphoniopropionate (DMSP), mixed layer depth (MLD), ice algae.