This will be especially important in low-lying coastal areas with high population and building densities (medium confidence).’ ‘Assuming that the physiological underpinning of the relationship between body size and temperature can be applied to warming (medium confidence), the body size of sandy beach crustaceans is expected to decrease under warming (low evidence, medium agreement).’ Sandy beaches transition from undetectable to moderate risk between 0.9°C and 1.8°C (medium confidence) of global sea surface warming and from moderate to high risk at 2.3°C–3.0°C of global sea surface warming