Extended Data Fig. 1: Observed and simulated MHW characteristics exceeding the 1982–2016 99th percentile, averaged over the 1982–2016 period.

a, b, Differences between the 99th percentile in SST and the annual mean SST. c, d, Annual mean duration of MHWs. e, f, Maximum annual intensity of MHWs. g, h, Annual cumulative mean intensity of MHWs. Satellite-derived patterns (a, c, e, g) and CMIP5 multi-model mean patterns (b, d, f, h). The black contours in all panels highlight the pattern structures. The spatial correlation between the CMIP5 multi-model mean and the satellite-based estimates is r² = 0.80 for a and b, r² = 0.15 for c and d, r² = 0.43 for e and f, and r² = 0.18 for g and h.