New Constraint on Future Ocean Heat Uptake Revealed by Considering Model Spread of Radiative Forcing

Abstract Radiative forcing is the fundamental driver of ocean heat uptake ; however, its contribution to intermodel spread in has not been quantified. We address this gap by leveraging a new set of CMIP6 experiments that diagnoses time‐varying for the first time in 11 models. Among them, we find that intermodel spread in is strongly affected by in historical simulations, but by model sensitivity in future projections. As a result, the correlation between historical and future is highly uncertain (0.1–0.7), whereas the correlation between historical and future is much more robust (0.8–0.9). For the 11 models, we show that imposing observed to constrain future can narrow its likely range by at least 10%. Finally, we emphasize that formulating as opens up new avenues for future ocean heat uptake studies.