Climate Dynamics

, Volume 37, Issue 5, pp 915–931

Albedo enhancement of marine clouds to counteract global warming: impacts on the hydrological cycle


    • Divecha Center for Climate ChangeIndian Institute of Science
    • Center for Atmospheric and Oceanic SciencesIndian Institute of Science
  • Ken Caldeira
    • Department of Global EcologyCarnegie Institution
  • Rama Nemani
    • NASA Ames Research Center
  • Long Cao
    • Department of Global EcologyCarnegie Institution
  • George Ban-Weiss
    • Department of Global EcologyCarnegie Institution
  • Ho-Jeong Shin
    • Department of Global EcologyCarnegie Institution

DOI: 10.1007/s00382-010-0868-1

Cite this article as:
Bala, G., Caldeira, K., Nemani, R. et al. Clim Dyn (2011) 37: 915. doi:10.1007/s00382-010-0868-1


Recent studies have shown that changes in solar radiation affect the hydrological cycle more strongly than equivalent CO2 changes for the same change in global mean surface temperature. Thus, solar radiation management “geoengineering” proposals to completely offset global mean temperature increases by reducing the amount of absorbed sunlight might be expected to slow the global water cycle and reduce runoff over land. However, proposed countering of global warming by increasing the albedo of marine clouds would reduce surface solar radiation only over the oceans. Here, for an idealized scenario, we analyze the response of temperature and the hydrological cycle to increased reflection by clouds over the ocean using an atmospheric general circulation model coupled to a mixed layer ocean model. When cloud droplets are reduced in size over all oceans uniformly to offset the temperature increase from a doubling of atmospheric CO2, the global-mean precipitation and evaporation decreases by about 1.3% but runoff over land increases by 7.5% primarily due to increases over tropical land. In the model, more reflective marine clouds cool the atmospheric column over ocean. The result is a sinking motion over oceans and upward motion over land. We attribute the increased runoff over land to this increased upward motion over land when marine clouds are made more reflective. Our results suggest that, in contrast to other proposals to increase planetary albedo, offsetting mean global warming by reducing marine cloud droplet size does not necessarily lead to a drying, on average, of the continents. However, we note that the changes in precipitation, evaporation and P-E are dominated by small but significant areas, and given the highly idealized nature of this study, a more thorough and broader assessment would be required for proposals of altering marine cloud properties on a large scale.


Climate changeGlobal warmingGeoengineeringSolar radiation managementMarine cloud-albedo enhancementHydrological cycle

Supplementary material

382_2010_868_MOESM1_ESM.doc (98 kb)
(DOC 97 kb)

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© Springer-Verlag 2010