Increase Asymmetric Warming Rates Between Daytime and Nighttime Temperatures Over Global Land During Recent Decades

Diurnal asymmetric warming, a critical feature of climate change, significantly impacts water-carbon exchange in terrestrial ecosystems. This study analyzes the spatiotemporal characteristics and long-term trends of the global diurnal temperature range (DTR) from 1961 to 2022 using ensemble empirical mode decomposition (EEMD). Our results reveal a trend reversal in global averaged DTR around 1988, shifting from a decrease to an increase, affecting 47% of global land areas. Subsequent to the reversal, the most pronounced increases were observed in temperate regions. Seasonal analysis shows earlier reversals in spring and summer, with accelerated change rates following the reversal. Additionally, increased surface solar radiation from reduced cloud cover caused daily maximum (Tmax) temperatures to warm faster than the minimum (Tmin), leading to a reversal and intensified DTR. These complex patterns underscore the need for targeted climate policies and adaptation strategies to tackle global warming.