Transient Climate Response


The transient climate response (TCR) 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. We calculate the temperature anomaly by subtracting a linear fit of the piControl run for all 140 years of the 1pctCO2 experiment prior to the TCR calculation (see Gregory and Forster, 2008).

Available recipes and diagnostics

Recipes are stored in recipes/

  • recipe_tcr.yml

Diagnostics are stored in diag_scripts/

  • climate_metrics/

  • climate_metrics/

  • climate_metrics/

User settings in recipe

  1. Preprocessor

    • area_statistics (operation: mean): Calculate global mean.

  2. Script climate_metrics/

    • plot, bool, optional (default: True): Plot temperature anomaly vs. time.

    • read_external_file, str, optional: Read TCR from external file. Can be given relative to the diagnostic script or as absolute path.

    • seaborn_settings, dict, optional: Options for seaborn’s set() method (affects all plots), see

  3. Script climate_metrics/

    See Equilibrium climate sensitivity.

  4. Script climate_metrics/

    See Equilibrium climate sensitivity.


  • tas (atmos, monthly, longitude, latitude, time)

Observations and reformat scripts



  • Gregory, J. M., and P. M. Forster. “Transient climate response estimated from radiative forcing and observed temperature change.” Journal of Geophysical Research: Atmospheres 113.D23 (2008).

Example plots


Fig. 89 Time series of the global mean surface air temperature anomaly (relative to the linear fit of the pre-industrial control run) of CanESM2 (CMIP5) for the 1% CO2 increase per year experiment. The horizontal dashed line indicates the transient climate response (TCR) defined as the 20 year average temperature anomaly centered at the time of CO2 doubling (vertical dashed lines).