Spatiotemporal evolution and drivers of diurnal temperature range extremes in recent decades

Diurnal temperature range (DTR) extremes — defined as DTR exceeding the historical 90th-percentile threshold — pose substantial risks to human health. Using global observations, we uncover a reversal in such extremes in the early 1980s: their frequency and cumulative intensity declined prior to this period but increased markedly thereafter over most land areas. Variations in cumulative intensity are primarily driven by changes in the frequency of DTR extremes. Composite analysis shows that such extremes are associated with local thermodynamic conditions that elevate daytime maximum temperatures and lower nighttime minimum temperatures, characterized by enhanced surface shortwave radiation, reduced cloud cover, soil drying, and precipitation deficits. Among these factors, widespread reductions in cloud cover emerge as the dominant driver of the intensification of such extremes since the 1980s. Spatially, cumulative intensity is higher across mid-to high-latitude and humid regions, largely controlled by surface shortwave radiation. Furthermore, urban population exposure has increased more rapidly than rural exposure over the past six decades. These findings provide a basis for assessing potential human health risks associated with extreme temperature variability.