The climate effects of increasing ocean albedo: an idealized representation of solar geoengineering

Abstract. Geoengineering, or climate intervention, describes methods of deliberately altering the climate system to offset anthropogenic climate change. As an idealized representation of near-surface solar geoengineering over the ocean, such as marine cloud brightening, this paper discusses experiment G1ocean-albedo of the Geoengineering Model Intercomparison Project (GeoMIP), involving an abrupt quadrupling of the CO2 concentration and an instantaneous increase in ocean albedo to maintain approximate net top-of-atmosphere radiative flux balance. A total of 11 Earth system models are relatively consistent in their temperature, radiative flux, and hydrological cycle responses to this experiment. Due to the imposed forcing, air over the land surface warms by a model average of 1.14 K, while air over most of the ocean cools. Some parts of the near-surface air temperature over ocean warm due to heat transport from land to ocean. These changes generally resolve within a few years, indicating that changes in ocean heat content play at most a small role in the warming over the oceans. The hydrological cycle response is a general slowing down, with high heterogeneity in the response, particularly in the tropics. While idealized, these results have important implications for marine cloud brightening, or other methods of geoengineering involving spatially heterogeneous forcing, or other general forcings with a strong land–ocean contrast. It also reinforces previous findings that keeping top-of-atmosphere net radiative flux constant is not sufficient for preventing changes in global mean temperature.

[1]  Ben Kravitz,et al.  Marine cloud brightening – as effective without clouds , 2017 .

[2]  Shingo Watanabe,et al.  Response to marine cloud brightening in a multi-model ensemble , 2017 .

[3]  Brian Zambri,et al.  The G4Foam Experiment: global climate impacts of regional ocean albedo modification , 2016 .

[4]  W. Hobbs,et al.  An Energy Conservation Analysis of Ocean Drift in the CMIP5 Global Coupled Models , 2016 .

[5]  Mark Lawrence,et al.  The impact of geoengineering on vegetation in experiment G1 of the GeoMIP , 2015 .

[6]  P. Rasch,et al.  A new method of comparing forcing agents in climate models , 2015 .

[7]  P. Forster,et al.  A comparison of temperature and precipitation responses to different Earth radiation management geoengineering schemes , 2015 .

[8]  Philip J. Rasch,et al.  Geoengineering as a design problem , 2015 .

[9]  D. Saint‐Martin,et al.  Land-sea warming contrast: the role of the horizontal energy transport , 2015, Climate Dynamics.

[10]  Ken Caldeira,et al.  Modeling of solar radiation management: a comparison of simulations using reduced solar constant and stratospheric sulphate aerosols , 2014, Climate Dynamics.

[11]  Duoying Ji,et al.  Description and basic evaluation of Beijing Normal University Earth System Model (BNU-ESM) version 1 , 2014 .

[12]  Hui Wan,et al.  Short ensembles: an efficient method for discerning climate-relevant sensitivities in atmospheric general circulation models , 2014 .

[13]  Olivier Boucher,et al.  Adjustments in the Forcing-Feedback Framework for Understanding Climate Change , 2014 .

[14]  K. Caldeira,et al.  Modeling of Solar Radiation Management: A comparison of simulations using reduced solar constant and stratospheric aerosols , 2014 .

[15]  O. Boucher,et al.  Arctic sea ice and atmospheric circulation under the GeoMIP G1 scenario , 2014 .

[16]  William M. Putman,et al.  Configuration and assessment of the GISS ModelE2 contributions to the CMIP5 archive , 2014 .

[17]  Shingo Watanabe,et al.  Arctic sea ice and atmospheric circulation under the GeoMIP G 1 scenario , 2014 .

[18]  Douglas G. MacMartin,et al.  Dynamics of the coupled human–climate system resulting from closed-loop control of solar geoengineering , 2014, Climate Dynamics.

[19]  Shingo Watanabe,et al.  An energetic perspective on hydrological cycle changes in the Geoengineering Model Intercomparison Project , 2013 .

[20]  Ben Kravitz,et al.  A multimodel examination of climate extremes in an idealized geoengineering experiment , 2013 .

[21]  Hauke Schmidt,et al.  Solar irradiance reduction via climate engineering: Impact of different techniques on the energy balance and the hydrological cycle , 2013 .

[22]  Michael Schulz,et al.  Sea‐salt injections into the low‐latitude marine boundary layer: The transient response in three Earth system models , 2013 .

[23]  Shingo Watanabe,et al.  The hydrological impact of geoengineering in the Geoengineering Model Intercomparison Project (GeoMIP) , 2013 .

[24]  P. Rasch,et al.  Sea spray geoengineering experiments in the geoengineering model intercomparison project (GeoMIP): Experimental design and preliminary results , 2013 .

[25]  W. Collins,et al.  The Community Earth System Model: A Framework for Collaborative Research , 2013 .

[26]  B. Stevens,et al.  Climate and carbon cycle changes from 1850 to 2100 in MPI‐ESM simulations for the Coupled Model Intercomparison Project phase 5 , 2013 .

[27]  A. Kirkevåg,et al.  The Norwegian Earth System Model, NorESM1-M – Part 1: Description and basic evaluation of the physical climate , 2013 .

[28]  S. Bony,et al.  Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5 , 2013, Climate Dynamics.

[29]  Cecilia M. Bitz,et al.  Time-Varying Climate Sensitivity from Regional Feedbacks , 2012 .

[30]  Ken Caldeira,et al.  Climate response to changes in atmospheric carbon dioxide and solar irradiance on the time scale of days to weeks , 2012 .

[31]  Mark Lawrence,et al.  Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO2: climate responses simulated by four earth system models , 2012 .

[32]  Karl E. Taylor,et al.  An overview of CMIP5 and the experiment design , 2012 .

[33]  Klaus Wyser,et al.  EC-Earth V2.2: description and validation of a new seamless earth system prediction model , 2012, Climate Dynamics.

[34]  C. Jones,et al.  Development and evaluation of an Earth-System model - HadGEM2 , 2011 .

[35]  Ø. Seland,et al.  Sensitivity to deliberate sea salt seeding of marine clouds – observations and model simulations , 2011 .

[36]  S. Emori,et al.  MIROC-ESM 2010: model description and basic results of CMIP5-20c3m experiments , 2011 .

[37]  Leon D. Rotstayn,et al.  The CSIRO Mk3L climate system model version 1.0 – Part 1: Description and evaluation , 2011 .

[38]  K. Taylor,et al.  The Geoengineering Model Intercomparison Project (GeoMIP) , 2011 .

[39]  K. Denman,et al.  Carbon emission limits required to satisfy future representative concentration pathways of greenhouse gases , 2011 .

[40]  Alan Robock.  Bubble, bubble, toil and trouble , 2011 .

[41]  C. Jones,et al.  Interactive comment on “ Development and evaluation of an Earth-system model – HadGEM 2 ” , 2011 .

[42]  R. Seitz,et al.  Bright water: hydrosols, water conservation and climate change , 2011 .

[43]  Ken Caldeira,et al.  Fast versus slow response in climate change: implications for the global hydrological cycle , 2010 .

[44]  Piers M. Forster,et al.  The transient response of global-mean precipitation to increasing carbon dioxide levels , 2010 .

[45]  William Finnegan,et al.  Modification of cirrus clouds to reduce global warming , 2009 .

[46]  J. Shepherd,et al.  Geoengineering the Climate: Science, Governance and Uncertainty , 2009 .

[47]  L. Oreopoulos,et al.  Radiative susceptibility of cloudy atmospheres to droplet number perturbations: 2. Global analysis from MODIS , 2008 .

[48]  J. Hansen,et al.  Efficacy of climate forcings , 2005 .

[49]  Jonathan M. Gregory,et al.  A new method for diagnosing radiative forcing and climate sensitivity , 2004 .

[50]  J. Latham,et al.  Control of global warming? , 1990, Nature.