Connecting warming patterns of the paleo-ocean to our future

Evolution of the spatial pattern of ocean surface warming impacts global radiative feedbacks, but different climate models have yielded different estimates of the spatial pattern in future climate change. Paleoclimate data, particularly those from past warm climates can help constrain the future, equilibrium warming pattern. Here, employing a novel regression-based technique, we eliminated the temporal domain in sea surface temperature (SST) over the past 10 million years to reveal the underlying spatial pattern of SST changes during global warming, facilitating direct comparisons between past climate data and present/future climates. Long and globally distributed paleo-SSTs are regressed onto records from the Western Pacific Warm Pool (WPWP), the warmest endmember of the global ocean, and the resulting regression slope is used to quantify the SST change of non-WPWP regions relative to the WPWP. We thereby identify a distinct spatial pattern of amplified warming that aligns with the patterns observed in certain equilibrated model simulations under high CO2 conditions. The agreement between paleoclimate records and model outputs showcases the convergence of efforts to understand Earth's past and predict its future climates. Collectively they help us to define an equilibrium warming pattern that substantially differs from the transient pattern observed over the past 160 years, illuminating our potential future path of “pattern effect” and its impact on global mean surface temperature change.