Coarse climate model grids underestimate coastal humid-heat extremes.

IFS-FESOM at ~9 km reproduces observed upper-tail wet-bulb temperature (TW) extremes near the Arabian Peninsula, while coarse gridding suppresses coastal daily-maximum TW by up to 8°C.

• Why it matters: Coarse climate grids may miss localized humid-heat peaks that approach human survivability limits, leaving coastal risk underestimated.
• What they did: Using nextGEMS fully coupled ICON and IFS-FESOM simulations (original ~9 km) versus station observations, ERA5, and CMIP6, the study tests how spatial smoothing changes coastal TW extremes and exceedance frequencies.
• The result: Spatial smoothing reduces daily-maximum TW extremes by up to 8°C and lowers exceedance frequencies across thresholds, and native-resolution fields show stronger mid-century exposure increases under SSP3-7.0 than coarse grids.

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