Historical Ocean Heat Uptake in Two Pairs of CMIP6 Models: Global and Regional Perspectives

Abstract Ocean heat content (OHC) is one of the most relevant metrics tracking current global heating. Therefore, simulated OHC time series are a cornerstone for assessing scientific performance Earth system models and climate models. Here we present detailed analysis change in simulations historical (1850–2014) performed with two pairs CMIP6 models: U.K. System Model 1 (UKESM1.0) HadGEM3-GC3.1-LL, CNRM-ESM2-1 CNRM-CM6-1. The small number enables us to analyze globally individual ocean basins, making use novel ensemble observational products. For top 700 m ocean, CNRM reproduce observed since 1960s closely. (UKESM1.0-LL HadGEM3-GC3.1-LL) compensate lack warming 0–700 layer 1970s 1980s below 2000 m. between substantially underestimated by all An increased relevance uptake Atlantic after 1991—suggested observations—is picked up but less so models, probably related an AMOC strengthening regional characteristics differ even though four share same component (NEMO ORCA1). Differences global, full-depth can be attributed differences model’s total effective radiative forcing.