Fig. 1: Values of DHM with a 3-month accumulation window versus DHW at the Great Barrier Reef over the 2001–2020 period.
From: Coral bleaching and mortality overestimated in projections based on Degree Heating Months
Heat stress calculated using DHM typically exceeds that calculated using DHW for observational and climate model data. a–g, Outer plots show cumulative frequency of heat stress (°C weeks) from DHM with a 3-month window versus DHW calculated from observed SST data (a) and hindcast SST data (six CMIP5 climate models: GISS-E2-R (b), GFDL-ESM2M (c), CESM1-WACCM (d), CCSM4 (e), HadGEM2-ES (f) and MIROC5 (g)), for 2,014 reefs of Australia’s Great Barrier Reef over 2001–2020. The widely used predictive criteria for substantial bleaching (≥4 °C weeks but <8 °C weeks) and for severe bleaching with substantial mortality (≥8 °C weeks) are shown by the shaded areas. Cumulative frequencies are normalized to 1. Insets: scatter plots depicting every value of DHM plotted against the corresponding value of DHW, both expressed as °C weeks. DHM was standardized to a weekly basis through multiplication by 4.
