Constraining clouds and convective parameterizations in a climate model using paleoclimate data

We provide a proof-of-concept study to constrain these parameterizations in a perturbed parameter ensemble of the atmosphere-only version of the Goddard Institute for Space Studies Model E2.1 simulations by evaluating model biases in the present-day runs using multiple satellite climatologies and by comparing simulated delta O-18 of precipitation (delta O-18(p)), known to be sensitive to parameterization schemes, with a global database of speleothem delta O-18 records covering the Last Glacial Maximum (LGM), mid-Holocene (MH) and pre-industrial (PI) periods.

Relative to modern interannual variability, paleoclimate simulations show greater sensitivity to parameter changes, allowing for an evaluation of model uncertainties over a broader range of climate forcing and the identification of parts of the world that are parameter sensitive. Certain simulations reproduced absolute delta O-18(p) values across all time periods, along with LGM and MH delta O-18(p) anomalies relative to the PI, better than the default parameterization.