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Enhanced marine sulphur emissions offset global warming and impact rainfall.

Grandey BS, Wang C - Sci Rep (2015)

Bottom Line: 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.We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world.These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate.

View Article: PubMed Central - PubMed

Affiliation: Center for Environmental Sensing and Modeling, Singapore-MIT Alliance for Research and Technology, Singapore.

ABSTRACT
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.

No MeSH data available.


Differences in annual mean radiative surface temperature (T).(a) RCP4.5 averaged across 2040–2059—Ref (the reference, RCP4.5 averaged across 2010–2029). (b) EnDMS averaged across 2040–2059—Ref. (c) EnDMS—RCP4.5, averaged across 2040–2059. (d) RCP4.5 averaged across 2080–2099—Ref. (e) EnDMS averaged across 2080–2099—Ref. (f) EnDMS—RCP4.5, averaged across 2080–2099. Years are defined to start in December. Ensemble means are used. Area-weighted mean differences are shown in purple text at the side of each map. White indicates locations where the differences do not have the same sign for all three sets of initial conditions. Stippling in (b,e) indicates locations where the EnDMS−Ref difference is larger in magnitude than the RCP4.5−Ref difference for that period. The figure was created using Python.
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f3: Differences in annual mean radiative surface temperature (T).(a) RCP4.5 averaged across 2040–2059—Ref (the reference, RCP4.5 averaged across 2010–2029). (b) EnDMS averaged across 2040–2059—Ref. (c) EnDMS—RCP4.5, averaged across 2040–2059. (d) RCP4.5 averaged across 2080–2099—Ref. (e) EnDMS averaged across 2080–2099—Ref. (f) EnDMS—RCP4.5, averaged across 2080–2099. Years are defined to start in December. Ensemble means are used. Area-weighted mean differences are shown in purple text at the side of each map. White indicates locations where the differences do not have the same sign for all three sets of initial conditions. Stippling in (b,e) indicates locations where the EnDMS−Ref difference is larger in magnitude than the RCP4.5−Ref difference for that period. The figure was created using Python.

Mentions: In the RCP4.5 ensemble, the global mean surface temperature increases by over 2 °C over the twenty-first century (Fig. 2a), primarily due to increased greenhouse gas induced warming. Over land, the mean surface warming is approximately 3 °C (Fig. 2b). On average, the oceans warm more slowly than land, partly due to the mixing of heat into the ocean, and partly due to other feedbacks20. The warming is spatially inhomogeneous (Fig. 3a,d). The largest warming occurs over the Arctic, due to surface albedo and temperature feedbacks21. Cooling, as opposed to warming, occurs over part of the North Atlantic ocean, south of Greenland22.


Enhanced marine sulphur emissions offset global warming and impact rainfall.

Grandey BS, Wang C - Sci Rep (2015)

Differences in annual mean radiative surface temperature (T).(a) RCP4.5 averaged across 2040–2059—Ref (the reference, RCP4.5 averaged across 2010–2029). (b) EnDMS averaged across 2040–2059—Ref. (c) EnDMS—RCP4.5, averaged across 2040–2059. (d) RCP4.5 averaged across 2080–2099—Ref. (e) EnDMS averaged across 2080–2099—Ref. (f) EnDMS—RCP4.5, averaged across 2080–2099. Years are defined to start in December. Ensemble means are used. Area-weighted mean differences are shown in purple text at the side of each map. White indicates locations where the differences do not have the same sign for all three sets of initial conditions. Stippling in (b,e) indicates locations where the EnDMS−Ref difference is larger in magnitude than the RCP4.5−Ref difference for that period. The figure was created using Python.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543957&req=5

f3: Differences in annual mean radiative surface temperature (T).(a) RCP4.5 averaged across 2040–2059—Ref (the reference, RCP4.5 averaged across 2010–2029). (b) EnDMS averaged across 2040–2059—Ref. (c) EnDMS—RCP4.5, averaged across 2040–2059. (d) RCP4.5 averaged across 2080–2099—Ref. (e) EnDMS averaged across 2080–2099—Ref. (f) EnDMS—RCP4.5, averaged across 2080–2099. Years are defined to start in December. Ensemble means are used. Area-weighted mean differences are shown in purple text at the side of each map. White indicates locations where the differences do not have the same sign for all three sets of initial conditions. Stippling in (b,e) indicates locations where the EnDMS−Ref difference is larger in magnitude than the RCP4.5−Ref difference for that period. The figure was created using Python.
Mentions: In the RCP4.5 ensemble, the global mean surface temperature increases by over 2 °C over the twenty-first century (Fig. 2a), primarily due to increased greenhouse gas induced warming. Over land, the mean surface warming is approximately 3 °C (Fig. 2b). On average, the oceans warm more slowly than land, partly due to the mixing of heat into the ocean, and partly due to other feedbacks20. The warming is spatially inhomogeneous (Fig. 3a,d). The largest warming occurs over the Arctic, due to surface albedo and temperature feedbacks21. Cooling, as opposed to warming, occurs over part of the North Atlantic ocean, south of Greenland22.

Bottom Line: 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.We find that the cooling effect associated with enhanced DMS emissions beneficially offsets greenhouse gas induced warming across most of the world.These results demonstrate that changes in marine phytoplankton activity may lead to a mixture of positive and negative impacts on the climate.

View Article: PubMed Central - PubMed

Affiliation: Center for Environmental Sensing and Modeling, Singapore-MIT Alliance for Research and Technology, Singapore.

ABSTRACT
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.

No MeSH data available.