Comparison of equilibrium climate sensitivity estimates from slab ocean, 150-year, and longer simulations

Consistent with previous work, ECS estimates from shorter coupled simulations based on annual averages for years 1-150 underestimate those from SOM (-8% +/- 13%) and long (-14% +/- 8%) simulations.

Analysis of only years 21-150 improved agreement with SOM (-2% +/- 14%) and long (-8% +/- 10%) estimates. Use of pentadal averages for years 51-150 results in improved agreement with long simulations (-4% +/- 11%). While ECS estimates from current generation U.S. models based on SOM and coupled annual averages of years 1-150 range from 2.6 degrees C to 5.3 degrees C, estimates based longer simulations of the same models range from 3.2 degrees C to 7.0 degrees C. Such variations between methods argues for caution in comparison and interpretation of ECS estimates across models.