Satellite observations over the past four decades revealed enhanced warming over the subtropical Pacific Ocean, a pattern resembling the negative phase of the Pacific Decadal Oscillation (PDO). Consequently, this pattern has been widely interpreted as a manifestation of natural climate variability. In this study, we revisit the observed warming pattern and find that the pronounced warming of subtropical oceans is not confined to the Pacific, but is present in every ocean basin. Moreover, within each basin, the warming exhibits a westward-intensified structure that closely resembles the structure of subtropical gyres. By combining observations, CMIP6 multi-model ensemble projections, and numerical sensitivity experiments, we argue that this pattern is most likely a manifestation of anthropogenic climate warming: subtropical gyres are characterized by surface convergence, and under greenhouse forcing, surface heat tends to accumulate in subtropical regions, generating a warming pattern that similar to the structure of the subtropical gyres. Further analysis reveals that this warming pattern emerges only during the early stages of climate warming, and progressively transitions toward a high-latitude-amplified warming pattern over time. Our findings offer insights into understanding the current ocean warming pattern and projecting its future evolution.

ocean warming pattern,subtropcial gyre,global warming