LGM paleoclimate constraints inform cloud parameterizations and equilibrium climate sensitivity in CESM2

Zhu, Jiang; Otto‐Bliesner, Bette L.; Brady, Esther C.; Poulsen, Christopher J.; Shaw, Jonah; Kay, J. E.

doi:10.1002/essoar.10507790.1

Cited by 8 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This occurs because of a particularly large cloud feedback sensitivity to SST patterns (gray dot furthest from the one-to-one line, Figure 3). Zhu et al (2022) argue that an issue in CESM2's cloud microphysics related to cloud ice number leads to an unrealistically large cloud sensitivity to warming in this model. Whether this is responsible for the model's large pattern effect is unclear.…”

Section: Table 2 Feedback Parameter In Amip-piforcing and Hadsst-pifo...mentioning

confidence: 90%

On the Effect of Historical SST Patterns on Radiative Feedback

et al. 2022

View full text Add to dashboard Cite

We investigate the dependence of radiative feedback on the pattern of sea‐surface temperature (SST) change in 14 Atmospheric General Circulation Models (AGCMs) forced with observed variations in SST and sea‐ice over the historical record from 1871 to near‐present. We find that over 1871–1980, the Earth warmed with feedbacks largely consistent and strongly correlated with long‐term climate sensitivity feedbacks (diagnosed from corresponding atmosphere‐ocean GCM abrupt‐4xCO2 simulations). Post 1980, however, the Earth warmed with unusual trends in tropical Pacific SSTs (enhanced warming in the west, cooling in the east) and cooling in the Southern Ocean that drove climate feedback to be uncorrelated with—and indicating much lower climate sensitivity than—that expected for long‐term CO2 increase. We show that these conclusions are not strongly dependent on the Atmospheric Model Intercomparison Project (AMIP) II SST data set used to force the AGCMs, though the magnitude of feedback post 1980 is generally smaller in nine AGCMs forced with alternative HadISST1 SST boundary conditions. We quantify a “pattern effect” (defined as the difference between historical and long‐term CO2 feedback) equal to 0.48 ± 0.47 [5%–95%] W m−2 K−1 for the time‐period 1871–2010 when the AGCMs are forced with HadISST1 SSTs, or 0.70 ± 0.47 [5%–95%] W m−2 K−1 when forced with AMIP II SSTs. Assessed changes in the Earth's historical energy budget agree with the AGCM feedback estimates. Furthermore satellite observations of changes in top‐of‐atmosphere radiative fluxes since 1985 suggest that the pattern effect was particularly strong over recent decades but may be waning post 2014.

show abstract

Section: Table 2 Feedback Parameter In Amip-piforcing and Hadsst-pifo...mentioning

confidence: 90%

On the Effect of Historical SST Patterns on Radiative Feedback

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Heterogeneous nucleation processes are still able to increase ice crystal mass, however, and can artificially inflate ice crystal size and increase sedimentation. This model error has been shared with model developers and identified as an issue to be resolved in future releases of CAM (personal communications, A. Gettelman, 2021), and one global correction significantly alters the climate sensitivity of CESM2 (Zhu et al, 2021).…”

Section: Model Modificationsmentioning

confidence: 99%

Using Satellite Observations to Evaluate Model Microphysical Representation of Arctic Mixed‐Phase Clouds

Shaw

McGraw

Bruno

et al. 2022

Geophysical Research Letters

View full text Add to dashboard Cite

Uncertainties in cloud and aerosol radiative effects are a principal contributor to climate model uncertainty, and remain so despite decades of model development (Boucher et al., 2013). These uncertainties arise from the difficulty of representing aerosol-cloud interactions and other key physical processes at the typical resolutions of global climate models (GCMs). Evaluations of available models from the Coupled Model Intercomparison Project Phase 6 (CMIP6; Eyring et al., 2016) indicate that changes in climate sensitivity relative to CMIP5 (Taylor et al., 2012) are mostly due to changes in cloud representation, specifically for extratropical low-level clouds (Zelinka et al., 2020). Using observations to reevaluate the representation of these clouds in the latest generation of GCMs is a vital part of testing the validity of these new predictions.In the Arctic, clouds mediate climate change through interactions with land and sea ice, and impacts on surface radiative fluxes (H. Morrison et al., 2012). As the thermodynamic phase of Arctic clouds shifts from ice to liquid in response to warming, the radiative effect they exert on the surface changes (Mitchell et al., 1989). This cloud phase feedback depends on cloud optical thickness and lifetime changes. In the Arctic, observations indicate that liquid and ice clouds exert very different radiative forcings on the surface

show abstract

“…This occurs because of a particularly large cloud feedback sensitivity to SST patterns (grey dot furthest from the one-to-one line, Figure 3). Zhu et al (2022) argue that an issue in CESM2's cloud microphysics related to cloud ice number leads to an unrealistically large cloud sensitivity to warming in this model. Whether this is responsible for the model's large pattern effect is unclear.…”

Section: Considering the Historical Record As A Wholementioning

confidence: 90%

On the effect of historical SST patterns on radiative feedback

Andrews

Gregory

Dong

et al. 2022

Preprint

View full text Add to dashboard Cite

We investigate the dependence of radiative feedback on the pattern of sea-surface temperature (SST) change in fourteen Atmospheric General Circulation Models (AGCMs) forced with observed variations in SST and sea-ice over the historical record from 1871 to near-present. We find that over 1871-1980, the Earth warmed with feedbacks largely consistent and strongly correlated with longterm climate sensitivity feedbacks (diagnosed from corresponding atmosphere-ocean GCM abrupt-4xCO2 simulations). Post 1980 however, the Earth warmed with unusual trends in tropical Pacific SSTs (enhanced warming in the west, cooling in the east) that drove climate feedback to be uncorrelated with -and indicating much lower climate sensitivity than -that expected for long-term CO 2 increase. We show that these conclusions are not strongly dependent on the AMIP II SST dataset used to force the AGCMs, though the magnitude of feedback post 1980 is generally smaller in eight AGCMs forced with alternative HadISST1 SST boundary conditions. We quantify a 'pattern effect' (defined as the difference between historical and long-term CO 2 feedback) equal to 0.44 ± 0.47 [5-95%] W m -2 K -1 for the time-period 1871-2010, which increases by 0.05 ± 0.04 W m -2 K -1 if calculated over 1871-2014. Assessed changes in the Earth's historical energy budget are in agreement with the AGCM feedback estimates. Furthermore satellite observations of changes in top-of-atmosphere radiative fluxes since 1985 suggest that the pattern effect was particularly strong over recent decades, though this may be waning post 2014 due to a warming of the eastern Pacific.

show abstract

LGM paleoclimate constraints inform cloud parameterizations and equilibrium climate sensitivity in CESM2

Cited by 8 publications

References 0 publications

On the Effect of Historical SST Patterns on Radiative Feedback

On the Effect of Historical SST Patterns on Radiative Feedback

Using Satellite Observations to Evaluate Model Microphysical Representation of Arctic Mixed‐Phase Clouds

On the effect of historical SST patterns on radiative feedback

Contact Info

Product

Resources

About