Projected increase in diurnal and interdiurnal variations of European summer temperatures

Beyond the mean warming, climate change may modify the temperature variability, with consequences on extreme events causing societal and environmental impacts. Here we assess future changes in both the interdiurnal variability (ITV) and diurnal range (DTR) of European summer temperatures based on Fifth Phase of the Coupled Model Intercomparison Project projections under three 21st century scenarios. Both indices are projected to increase, with a rather good model agreement on the sign, while uncertainties remain on the amplitude. Extremely high day-to-day and diurnal temperature variations are expected to occur more frequently. Across models and scenarios, ITV and DTR increases vary primarily as functions of the decrease in surface evapotranspiration linked to the European summer drying. They are also partly explained by changes in the atmospheric dynamics and the surface cloud radiative effect. Model-dependent degrees of control of (i) ITV and DTR by mean temperature and (ii) surface evapotranspiration by soil moisture appear as helpful metrics to reduce future uncertainties in ITV and DTR projections.