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144320 - Coral-reef-derived dimethyl sulfide and the climatic impact.pdf (12.25 MB)

Coral-reef-derived dimethyl sulfide and the climatic impact of the loss of coral reefs

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posted on 2023-05-20, 23:17 authored by Sonya FiddesSonya Fiddes, Woodhouse, MT, Lane, TP, Schofield, R
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 flux of 0.3 Tg yr−1 S, or 1.7 % of the global sulfur flux from DMS. 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 exists, 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.

History

Publication title

Atmospheric Chemistry and Physics

Volume

21

Issue

8

Pagination

5883-5903

ISSN

1680-7316

Department/School

Institute for Marine and Antarctic Studies

Publisher

Copernicus GmbH

Place of publication

Germany

Rights statement

© Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) License. (https://creativecommons.org/licenses/by/4.0/)

Repository Status

  • Open

Socio-economic Objectives

Climate change models; Effects of climate change on Australia (excl. social impacts)

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