Simulated Changes and Future Analogy Extent of Ocean Heat Content During the Mid‐Pliocene Warm Period

In the present day, global oceans have absorbed most of the excess anthropogenic heat, abating surface temperature warming. The Mid-Pliocene Warm Period (MPWP; ~3.2 million years ago) offers an opportunity to understand how globally warmer climates store oceanic heat. We use the PlioMIP2 model ensemble to quantify global ocean heat content (OHC), defined as that in the 0–700 m fixed-depth layer, and present an overview of the spatial characteristics of Indo-Pacific OHC during the MPWP. Simulated MPWP OHC is globally higher than the pre-industrial except for the Arabian Sea, which is attributed to weakened Northeast monsoon wind strength. The equatorial Pacific thermocline warms by ~2°C from pre-industrial to the MPWP without deepening. Globally, MPWP OHC exceeds the highest SSP5-8.5 future scenario for the late 21st century (2081–2100), suggesting the ocean can absorb substantial amounts of heat, though the dynamics of heat uptake remain important given potential nonlinearities.