A113-0010
Comparison of CMIP6 Equilibrium Climate Sensitivity to that Inferred from the Century and a Half Long Climate Record Using an Empirical Model of Global Climate

Friday, 11 December 2020
Poster
Laura McBride1, Austin Patrick Hope2, Timothy Canty3, Brian Francis Bennett4, Walter Robert Tribett2 and Ross J Salawitch5, (1)University of Maryland College Park, Department of Chemistry and Biochemistry, College Park, MD, United States, (2)University of Maryland College Park, Department of Atmospheric and Oceanic Science, College Park, MD, United States, (3)University of Maryland, College Park, MD, United States, (4)University of Maryland, Department of Atmospheric and Oceanic Science, College Park, MD, United States, (5)University of Maryland, AOSC and Chemistry, College Park, MD, United States
Abstract:
The sixth phase of the Coupled Model Intercomparison Project (CMIP6) is the latest modeling effort for General Circulation Models (GCMs) to estimate equilibrium climate sensitivity (ECS). We will analyze near surface air temperature and net downward radiative flux output from the Abrupt 4×CO2 experiment to calculate ECS for comparison to values of ECS based on the observed temperature record. ECS from the climate record is found by using an Empirical Model of Global Climate (EM-GC) (Canty et al., ACP, 2013) that accounts for the natural influences on global mean surface temperature due to ENSO, the 11-year solar cycle, major volcanic eruptions, as well as the anthropogenic influence of greenhouse gases and aerosols and the efficiency of ocean heat uptake. Preliminary analysis shows that the best estimate of ECS based on the observed temperature record is 2.01°C with a range of 1.12-4.12°C (5th and 95th percent confidence interval), compared to a value for ECS of 3.84°C with a range of 2.36-5.69°C (5th and 95th percent confidence interval) from the CMIP6 multi-model ensemble. Our results support the view of many in the climate community, including the recent study by Sherwood et al. (Reviews of Geophysics, 2020), that the true value of ECS is likely not as large as suggested by some of the CMIP6 GCMs. We’ll also compare estimates of the attributable anthropogenic warming rate (AAWR) inferred from the climate record over the past four decades to values of AAWR from the CMPI6 GCMs, to further assess the behavior of the climate model computations underlying the upcoming IPCC report.
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