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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.


Related in: MedlinePlus

Time series of annual mean radiative surface temperature (T) for the RCP4.5 and EnDMS ensembles.(a) Global (land and ocean) area-weighted annual mean T. (b) Global land-only area-weighted annual mean T, using a land fraction threshold of 0.9. The thinner blue lines show annual means for each simulation in the RCP4.5 three-member mini-ensemble. The thicker blue lines show robust locally weighted regression smoothing (LOESS) curves3738, which have been calculated using a smoothing parameter of f = 0.6 and three iterations of fitting, using the RCP4.5 ensemble mean as input. The red lines correspond to the EnDMS ensemble. The green dashed lines illustrate the lag between the RCP4.5 and the EnDMS LOESS curves at the end of the twenty-first century. Years are defined to start in December, so that the December-January-February season is not divided across different annual means. Hence, when calculating annual means for any given year, data from December in the given year are excluded while data from the previous year are included.
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f2: Time series of annual mean radiative surface temperature (T) for the RCP4.5 and EnDMS ensembles.(a) Global (land and ocean) area-weighted annual mean T. (b) Global land-only area-weighted annual mean T, using a land fraction threshold of 0.9. The thinner blue lines show annual means for each simulation in the RCP4.5 three-member mini-ensemble. The thicker blue lines show robust locally weighted regression smoothing (LOESS) curves3738, which have been calculated using a smoothing parameter of f = 0.6 and three iterations of fitting, using the RCP4.5 ensemble mean as input. The red lines correspond to the EnDMS ensemble. The green dashed lines illustrate the lag between the RCP4.5 and the EnDMS LOESS curves at the end of the twenty-first century. Years are defined to start in December, so that the December-January-February season is not divided across different annual means. Hence, when calculating annual means for any given year, data from December in the given year are excluded while data from the previous year are included.

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)

Time series of annual mean radiative surface temperature (T) for the RCP4.5 and EnDMS ensembles.(a) Global (land and ocean) area-weighted annual mean T. (b) Global land-only area-weighted annual mean T, using a land fraction threshold of 0.9. The thinner blue lines show annual means for each simulation in the RCP4.5 three-member mini-ensemble. The thicker blue lines show robust locally weighted regression smoothing (LOESS) curves3738, which have been calculated using a smoothing parameter of f = 0.6 and three iterations of fitting, using the RCP4.5 ensemble mean as input. The red lines correspond to the EnDMS ensemble. The green dashed lines illustrate the lag between the RCP4.5 and the EnDMS LOESS curves at the end of the twenty-first century. Years are defined to start in December, so that the December-January-February season is not divided across different annual means. Hence, when calculating annual means for any given year, data from December in the given year are excluded while data from the previous year are included.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Time series of annual mean radiative surface temperature (T) for the RCP4.5 and EnDMS ensembles.(a) Global (land and ocean) area-weighted annual mean T. (b) Global land-only area-weighted annual mean T, using a land fraction threshold of 0.9. The thinner blue lines show annual means for each simulation in the RCP4.5 three-member mini-ensemble. The thicker blue lines show robust locally weighted regression smoothing (LOESS) curves3738, which have been calculated using a smoothing parameter of f = 0.6 and three iterations of fitting, using the RCP4.5 ensemble mean as input. The red lines correspond to the EnDMS ensemble. The green dashed lines illustrate the lag between the RCP4.5 and the EnDMS LOESS curves at the end of the twenty-first century. Years are defined to start in December, so that the December-January-February season is not divided across different annual means. Hence, when calculating annual means for any given year, data from December in the given year are excluded while data from the previous year are included.
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.


Related in: MedlinePlus