.. _recipes_meehl20sciadv:

Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models
==========================================================================================================================

Overview
--------

This recipe reproduces the analysis of `Meehl et al., Sci. Adv. (2020)`_. In
this paper, the equilibrium climate sensitivity (ECS) and transient climate
response (TCR) are evaluated for the CMIP6 models and put into historical
context.

.. _`Meehl et al., Sci. Adv. (2020)`: https://advances.sciencemag.org/content/6/26/eaba1981


Available recipes and diagnostics
---------------------------------

Recipes are stored in recipes/

   * recipe_meehl20sciadv.yml

Diagnostics are stored in diag_scripts/

   * climate_metrics/ecs.py
   * climate_metrics/tcr.py
   * climate_metrics/create_table.py
   * ipcc_ar5/ch09_fig09_42b.py


User settings in recipe
-----------------------

* Script climate_metrics/ecs.py

   See :ref:`here<ecs.py>`.


* Script climate_metrics/tcr.py

   See :ref:`here<tcr.py>`.


* Script climate_metrics/create_table.py

   * ``calculate_mean``, *bool*, optional (default: ``True``): Calculate
     mean over all datasets and add it to table.
   * ``calculate_std``, *bool*, optional (default: ``True``): Calculate
     standard deviation over all datasets and add it to table.
   * ``exclude_datasets``, *list of str*, optional (default:
     ``['MultiModelMean']``): Exclude certain datasets when calculating
     statistics over all datasets and for assigning an index.
   * ``patterns``, *list of str*, optional: Patterns to filter list of input
     data.
   * ``round_output``, *int*, optional: If given, round output to given
     number of decimals.


* Script ipcc_ar5/ch09_fig09_42b.py

   See :ref:`here<ch09_fig09_42b.py>`.


Variables
---------

* *rlut* (atmos, monthly, longitude, latitude, time)
* *rsdt* (atmos, monthly, longitude, latitude, time)
* *rsut* (atmos, monthly, longitude, latitude, time)
* *tas* (atmos, monthly, longitude, latitude, time)



References
----------

* Meehl, G. A., Senior, C. A., Eyring, V., Flato, G., Lamarque, J. F.,
  Stouffer, R. J., Taylor, K. E. and Schlund, M., *Context for interpreting
  equilibrium climate sensitivity and transient climate response from the CMIP6
  Earth system models*, Science Advances, 6(26), eaba1981,
  `<https://doi.org/10.1126/sciadv.aba1981>`_, 2020.


Example plots
-------------

.. _fig_meehl20sciadv_1:
.. figure:: /recipes/figures/meehl20sciadv/cmip6_gregory_regression.png
   :align: center
   :width: 50%

   ECS calculated for the CMIP6 models using the Gregory method over different
   time scales. Using the entire 150-year 4xCO2 experiment (black line), there
   is an ECS value of 3.8 K; using only the first 20 years (blue dots and blue
   line), there is an ECS of 3.4 K; and using the last 130 years, there is an
   ECS of 4.1 K (orange dots and orange line).

.. _fig_meehl20sciadv_2:
.. figure:: /recipes/figures/meehl20sciadv/cmip6_tcr_vs_ecs.png
   :align: center
   :width: 50%

   TCR as a function of ECS for the CMIP6 models (black line is a linear fit).
   The :math:`R^2` values are given in the upper left parts of each panel. The
   numbers denote individual CMIP6 models.