Historical diurnal temperature range trends constrain future climate projections

The diurnal temperature range (DTR), which measures the difference between daily maximum and minimum temperatures, is a vital indicator of climate extremes. However, predicting future changes in DTR under global warming remains challenging due to significant uncertainties in model projections. This study uncovers a significant link between historical DTR trends and future projections on both global and regional scales. Leveraging this relationship, we introduce a constraining framework to enhance the accuracy of regional climate projections. The mechanism is that the changes in DTR are primarily driven by external forces such as greenhouse gas emissions, rather than internal climate variability. Increasing greenhouse gases reduces cloud cover, which migrates DTR decline by enhancing daytime shortwave radiation and reducing nighttime longwave radiation. While this relationship is generally robust across seasons, it weakens at high latitudes in winter due to minimal solar radiation. Our findings contribute to reducing uncertainties in model projections, offering valuable insights into future changes in DTR and their implications for regional climate responses