Comparison of transient climate response (TCR) and equilibrium climate sensitivity (ECS) from historical warming in CMIP6 models

The “transient climate response” is defined as the global and annual mean surface air temperature anomaly in the 1pctCO2 scenario (1% CO2 increase per year) for a 20 year period centered at the time of CO2 doubling, i.e. using the years 61 to 80 after the start of the simulation. The temperature anomaly was calculated by subtracting a linear fit of the piControl run for all 140 years of the 1pctCO2 experiment prior to the TCR calculation (see https://doi.org/10.1029/2008JD010405). The “equilibrium climate sensitivity" is the higher long-term increase in global average temperature expected to occur after the effects of a doubled CO2 concentration have had time to reach a steady state.