Satellite-observed sea surface temperature (SST) provides an unprecedented opportunity to evaluate the ongoing global warming and has recently reached a milestone of 40 years temporal coverage. One of the major warming patterns captured by satellites is relatively strong subtropical ocean warming across all ocean basins. This pattern was widely interpreted as a manifestation of the Pacific Decadal Oscillation, a natural climate variability. However, we find that the observed warming pattern, characterized by strong warming over the subtropical oceans and mild warming or even cooling over the subpolar oceans, is dynamically consistent with where the surface water converges and diverges. By comparing observations with paleo-reconstructions and simulated short-term and long-term SST response to CO2 forcing, we propose that the observed warming pattern is likely in a transient early warming stage constrained by background ocean circulation. In the long term, ocean warming at high latitudes is expected to exceed the temporally dominating subtropical ocean warming. The committed, but lagged, high-latitude ocean warming has potential to reshape the ocean-atmosphere circulation and threaten the stability of marine-terminating ice sheets.

global warming,satellite observation,ocean warming pattern,Paleoclimate reconstruction,climate modelling