Coral Thermometry Shows Exceptional 3˚C warming in the Subtropical North Pacific Over the Past Century

Abstract Tropical and subtropical oceans have warmed substantially over the past century, but model study reconstructions suggest that the rate of warming may differ greatly across regions. Sr/Ca ratios in massive Porites corals provide a reliable archive of past sea surface temperatures (SST), enabling high-resolution reconstructions of long-term climate trends. Yet many parts of the ocean remain underrepresented in such records, hindering a spatially resolved understanding of ocean warming. Here we present SST warming rates over the past century based on coral Sr/Ca records from Hawaii, which show an increase of 2.7 to 3.0 °C per century–far exceeding warming rates reported from other coral Sr/Ca records worldwide, most of which remain below 1.5 °C per century. This finding suggests that coral reef in the subtropical North Pacific may be warming more rapidly than previously recognized based on sparse reanalysis dataset.