Forcing and feedback in the MPI‐ESM‐LR coupled model under abruptly quadrupled CO2

By Karoline Block, T. Mauritsen. 2013

169 citations recorded by the source corpus.

Radiative feedback mechanisms associated with temperature, water vapor, cloud, and surface albedo change determine climate sensitivity to radiative forcing. Here we use the linearized radiative kernel‐technique in combination with a Gregory analysis to determine the strength and structure of feedbacks, as well as direct and adjusted CO2 forcings in the coupled Max Planck Institute Earth System Model at base resolution (MPI‐ESM‐LR). We show that the combined Kernel‐Gregory approach yields an elegant separation of surface temperature‐dependent feedbacks from contributions to radiative forcing by fast adjustments. MPI‐ESM‐LR exhibits a relatively large cloud adjustment of nearly 2 W m−2 in direct response to quadrupled CO2, with positive cloud adjustment evident throughout the tropics, subtropics and over most landmasses whereas midlatitude storm tracks contribute negatively. The model features a nonlinear regression of radiation imbalance to global mean surface temperature change, resulting in a significantly increasing effective climate sensitivity after about 20 years which is approximately at temperatures 4–5 K above preindustrial. This feature is not uncommon among climate models and is relevant for future climate projections. We analyze the contribution of the individual feedback processes to this behavior and discuss possible origins such as differential ocean warming patterns associated with deep‐ocean heat uptake or state dependencies of the feedback processes.

Subfields: Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/ac26fa9fc7aeaa9140a063e4f95d2b87aa4563f0

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Citations in the corpus

Climate and carbon cycle changes from 1850 to 2100 in MPI‐ESM simulations for the Coupled Model Intercomparison Project phase 5 (2013, unknown): “Instead, for this model it has been previously suggested to somewhat arbitrarily divide the run in two piecewise nearly linear portions of the first 20 years and the last 130 years of the simulation [Stevens and Bony, 2013; Block and Mauritsen, 2013]. Clearly, the total feedback factor is different ”
A global scale mechanistic model of photosynthetic capacity (LUNA V1.0) (2016, background): “Photosynthesis is one of the major components of the ecosys- tem carbon cycle (Canadell et al., 2007; Sellers et al., 1997) and is thus a key ingredient of Earth system models (ESMs) (Block and Mauritsen, 2013; Hurrell et al., 2013).”
Robust increase in equilibrium climate sensitivity under global warming (2013, background): “This technique yields an elegant separation between fast adjustments directly caused by the CO2 increase, which in ECHAM6 are primarily stratospheric adjustment and a fast cloud reduction, and true surface temperaturedependent feedbacks that are realized subsequently [Block and Mauritsen, 2013].”
Causes of Higher Climate Sensitivity in CMIP6 Models (2020, methodology): “We use the Huang et al. (2017) kernels because they yield the smallest residuals, but all results are qualitatively unchanged when using Soden et al. (2008), Shell et al. (2008), Block and Mauritsen (2013), Pendergrass et al. (2018), or Smith et al. (2018) kernels (Figure S2 and Text S1).”
Polar Amplification in CCSM4: Contributions from the Lapse Rate and Surface Albedo Feedbacks (2014, background): “In particular, the surface albedo kernel has been shown to be dependent on the climate (Block and Mauritsen 2013).”