Forcing, feedbacks and climate sensitivity in CMIP5 coupled atmosphere‐ocean climate models

We quantify forcing and feedbacks across available CMIP5 coupled atmosphere‐ocean general circulation models (AOGCMs) by analysing simulations forced by an abrupt quadrupling of atmospheric carbon dioxide concentration. This is the first application of the linear forcing‐feedback regression analysis of Gregory et al. (2004) to an ensemble of AOGCMs. The range of equilibrium climate sensitivity is 2.1–4.7 K. Differences in cloud feedbacks continue to be important contributors to this range. Some models show small deviations from a linear dependence of top‐of‐atmosphere radiative fluxes on global surface temperature change. We show that this phenomenon largely arises from shortwave cloud radiative effects over…

• UD
  U.S. Department of Energy
• DF
  Department for Environment, Food and Rural Affairs, UK Government

  Award: GA01101
• SR
  Sight Research UK

  Award: ncas10009
• MO
  Met Office

  Award: GA01101
• NE
  Natural Environment Research Council

  Award: ncas10009