ICE-CORE RECORD OF OCEANIC EMISSIONS OF DIMETHYLSULFIDE DURING THE LAST CLIMATE CYCLE

THE Vostok ice core in Antarctica has provided one of the longest climate records, enabling the stable-isotope, major-ion and gas composition of the atmosphere to be reconstructed over many thousands of years. Here we present depth profiles along this core of methanesulphonate and non-seasalt sulphate (produced by the atmospheric oxidation of dimethylsulphide), which provide the first historical record of biogenic sulphur emissions from the Southern Hemisphere oceans over a complete glacial-interglacial cycle (160 kyr). Those measurements confirm and extend some previous observations made on a very limited data set from the Dome C ice core in Antarctica, which indicated increased oceanic emissions of dimethylsulphide during the later stages of the glacial period, compared with the present day 1. The observed glacial-interglacial variations in methanesulphonate and non-seasalt sulphate confirm that the ocean-atmosphere sulphur cycle is extremely sensitive to climate change.