Review status: a revised version of this preprint is currently under review for the journal ACP.
Coral reef-derived dimethyl sulfide and the climatic impact of the
loss of coral reefs
Sonya L. Fiddes1,2,3,a,Matthew T. Woodhouse3,Todd P. Lane4,and Robyn Schofield4Sonya L. Fiddes et al.Sonya L. Fiddes1,2,3,a,Matthew T. Woodhouse3,Todd P. Lane4,and Robyn Schofield4
Received: 09 Oct 2020 – Accepted for review: 23 Oct 2020 – Discussion started: 27 Oct 2020
Abstract. Dimethyl sulfide (DMS) is a naturally occurring aerosol precursor gas which plays an important role in the global sulfur budget, aerosol formation and climate. While DMS is produced predominantly by phytoplankton, recent observational literature has suggested that corals and their symbionts produce a comparable amount of DMS, which is unaccounted for in models. It has further been hypothesised that the coral reef source of DMS may modulate regional climate. This hypothesis presents a particular concern given the current threat to coral reefs under anthropogenic climate change. In this paper, a global climate model with online chemistry and aerosol is used to explore the influence of coral reef-derived DMS on atmospheric composition and climate. A simple representation of coral reef-derived DMS is developed and added to a common DMS surface water climatology, resulting in an additional DMS flux of 0.3 Tg year−1 S, or 1.7 % of the global flux. By comparing the differences between both nudged and free running ensemble simulations with and without coral reef-derived DMS, the influence of coral reef-derived DMS on regional climate is quantified. In the Maritime Continent-Australian region, where the highest density of coral reefs exist, a small decrease in nucleation and Aitken mode aerosol number concentration and mass is found when coral reef DMS emissions are removed from the system. However, these small responses are found to have no robust effect on regional climate via direct and indirect aerosol effects. This work emphasises the complexities of the aerosol-climate system and the limitations of current modelling capabilities are highlighted, in particular surrounding convective responses to changes in aerosol. In conclusion we find no robust evidence that coral reef-derived DMS influences global and regional climate.
Coral reefs are known to produce the aerosol precursor dimethyl sulfide (DMS). Currently, this source of coral DMS is unaccounted for in climate modelling and the impact of coral reef extinction on aerosol and climate is unknown. In this study, we address this problem using a coupled chemistry-climate model for the first time. We find that coral reefs make a minimal contribution to the aerosol population, and are unlikely to play a role in climate modulation.
Coral reefs are known to produce the aerosol precursor dimethyl sulfide (DMS). Currently, this...