Increasing Global Terrestrial Diurnal Temperature Range for 1980–2021

The 2021 IPCC report found that most studies show declining trends for the global diurnal temperature range (DTR) since the 1950s, decreasing mainly during 1960–1980. This issue is revisited here using an up-to-date in-situ data set, Hadley Center Integrated Surface Database, constrained by rigorous station selection conditions. The global observed DTR trend was found to reverse during 1980–2021, increasing significantly at a rate of 0.091 ± 0.008°C decade⁻¹. The trend was dominated by a faster rate of increasing daily maximum air temperature. This increasing observed trend in the past four decades was not fully captured in raw CMIP6 models, as models only partially capture the spatial patterns. With global CMIP6 outputs and regionally-available observations, the global land DTR was then estimated, through emergent constraints, to be 0.063 ± 0.012°C decade⁻¹. The study raises concern for risks of increasing DTR globally and provides new insights into global DTR assessment.