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Response to marine cloud brightening in a multi-model ensemble

Profile image of Helene MuriHelene Muri

2017, Atmospheric Chemistry and Physics Discussions

https://doi.org/10.5194/ACP-2017-629
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Abstract

Here we show results from Earth System Model simulations from the marine cloud brightening experiment G4cdnc of the Geoengineering Model Intercomparison Project (GeoMIP). The nine contributing models prescribe a 50 % increase in the cloud droplet number concentration (CDNC) of low clouds over the global oceans, with the purpose of counteracting the radiative forcing due to anthropogenic greenhouse gases under the RCP4.5 scenario. The model ensemble median effective radiative forcing (ERF) amounts to −1.9 Wm<sup>−2</sup>, with a substantial inter-model spread of −0.6 to −2.5 Wm<sup>−2</sup>. The large spread is partly related to the considerable differences in clouds and their representation between the models, with an underestimation of low clouds in several of the models. All models predict a statistically significant temperature decrease with a median of (for years 2020–2060) −0.95 [−0.18 ...

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