Simulated increases of future Arctic dimethylsulfide ocean concentrations, emissions and high-flux events

Simulations from a regional ocean and sea ice model are presented to analyze the potential impacts of climate change on dimethylsulfide (DMS) ocean concentrations and emissions in the Arctic Ocean during the 21st century for a scenario of strong warming (RCP8.5, 2016–2085). The model used includes sulfur biogeochemistry in both the ocean and sea ice, representing the production of dimethylsulfoniopropionate and its conversion to DMS. Simulated DMS concentrations and emissions increase overall in the future throughout the Arctic. Substantial increases of summer ocean surface DMS concentrations and emissions are projected in the shallow continental shelves of the Eastern Arctic, due to a large reduction of sea ice cover. In the Central and Western Arctic, moderate increases of spring DMS production are trapped below sea ice even in the late 21st century. In deep basins, despite ice-free summers in the future, simulated DMS emissions are low, as DMS production occurs mostly below the mixed layer and remains at depth. The strong temporal variability of near-surface winds results in bursts of DMS emissions lasting a few days, with sea-to-air fluxes up to 10 times higher than the monthly median emissions rate. These spikes of DMS emissions occur throughout the Arctic, indicating an episodic impact of DMS on climate in areas of low mean DMS emissions. The simulated frequency of high-flux events increases during the 21st century in both spring and summer in almost all regions of the Arctic. However, the model is not capable of representing rapid out-gassing events during sea ice break-up, and improvements in the representation of leads are still necessary to fully assess the role of sea ice DMS production. With the ongoing decrease in anthropogenic sulfur emissions, these results suggest a future amplification of the role of DMS in aerosol and cloud formation in the Arctic.