Enhanced marine sulphur emissions offset global warming and impact rainfall

Grandey, B. S., and C. Wang (2015), Enhanced marine sulphur emissions offset global warming and impact rainfall, Scientific Reports, doi:10.1038/srep13055

Video Introduction

MIT News

A news release, written by Mark Dwortzan, can be read at http://globalchange.mit.edu/news-events/news/news_id/480 [URL added on 7-Sep-2015] or http://news.mit.edu/2015/fertilize-ocean-cool-planet-0908 [URL added on 9-Sep-2015].

Straits Times [23rd October 2015]

Audrey Tan has written a really well researched article in the Straits Times: http://www.straitstimes.com/singapore/shivers-over-growing-plankton-to-cool-earth [URL added on 23-Oct-2015]. I really like the Straits Times’ infographic.


Artificial fertilisation of the ocean has been proposed as a possible geoengineering method for removing carbon dioxide from the atmosphere. The associated increase in marine primary productivity may lead to an increase in emissions of dimethyl sulphide (DMS), the primary source of sulphate aerosol over remote ocean regions, potentially causing direct and cloud-related indirect aerosol effects on climate. This pathway from ocean fertilisation to aerosol induced cooling of the climate may provide a basis for solar radiation management (SRM) geoengineering. In this study, we investigate the transient climate impacts of two emissions scenarios: an RCP4.5 (Representative Concentration Pathway 4.5) control; and an idealised scenario, based on RCP4.5, in which DMS emissions are substantially enhanced over ocean areas. We use mini-ensembles of a coupled atmosphere-ocean configuration of CESM1(CAM5) (Community Earth System Model version 1, with the Community Atmosphere Model version 5). We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world. However, the rainfall response may adversely affect water resources, potentially impacting human livelihoods. These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate.


One thought on “Enhanced marine sulphur emissions offset global warming and impact rainfall

  1. Benjamin Grandey Post author

    Some interesting complementary work by another research group working independently from us, recently published online:

    J. Crook, L.S. Jackson, S.M. Osprey, and P.M. Forster (2015), “A Comparison of Temperature and Precipitation Responses to Different Earth Radiation Management Geoengineering Schemes”, DOI: 10.1002/2015JD023269, http://onlinelibrary.wiley.com/doi/10.1002/2015JD023269/abstract.

    Crook et al. investigate other SRM* geoengineering proposals using a different climate model from us. Despite these differences, they also highlight that an adverse rainfall response may arise if SRM were to be carried out. Taken together, Crook et al.’s paper and our paper provide a stronger case concerning this potential adverse impact of SRM.

    [*Crook et al. actually refer to “Earth Radiation Management”, rather than “Solar Radiation Management”, due to the fact that they also consider targeting outgoing longwave radiation via cirrus cloud changes in addition to incoming solar shortwave radiation.]


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