Abstract Climate model emulators were extensively used in the IPCCâs Sixth Assessment Report for their computational efficiency and consistency with key climate metrics. The emulators were calibrated to historical observations and used for future climate projections without systematic evaluation of their robustness. Here, we develop a framework to evaluate the performance of physical climate model emulators against global climate model (GCM) large ensembles. This is demonstrated by constraining a twoâlayer energy balance model (EBM) to historical simulations of four GCMs and comparing their 21st century warming projections. The EBM matches projected warming in three of the four GCMs but exhibits substantial ensemble spread. It fails to reproduce the timeâevolving global climate feedback in GCMs, with compensating biases between feedbacks and ocean heat uptake efficiency allowing seemingly accurate projections for incorrect reasons. Our results underscore the importance of evaluating the accuracy and physical realism of emulators before using them for warming projections.
Observations from the Little Bunker
Last updated: November 30, 2025 04:25 AM
Atmospheric COâ
426.8 ppm
+18.1
ppm/year
Atmospheric CHâ
1927.61 ppb
+2.73
ppb/year
Global Temperature
+1.48 °C
Peak: +1.73°C
World Population
8.1 billion
+67
million/year