Chalmers Climate Dynamics Group

Biological and ecological processes regulating the ecosystem carbon cycle exhibit varying sensitivities to temperature fluctuations during the day and night. Consequently, the diurnal temperature range (DTR)—the difference between daily maximum and minimum temperatures—plays an important role in modulating carbon assimilation and consumption in plants. Over recent decades, daytime warming has outpaced nighttime warming over land, leading to a widening of the DTR, which is expected to impact plant productivity. However, how the recent DTR changes have influenced vegetation productivity across various climate zones remains unclear. Using remote sensing data and flux tower measurements from 2002 to 2021, we found divergent impacts of increased DTR on vegetation productivity in the extratropical Northern Hemisphere. In humid zones, summer DTR increases have promoted net primary production (NPP), while the opposite effect is found in arid zones. This contrast can largely be explained by the larger impact of accelerated daytime warming on increased vapor pressure deficit in arid zones, which consequently inhibits NPP. Our findings underscore the non-negligible impacts of recent DTR changes on vegetation productivity, emphasizing the need to consider sub-diurnal variations in assessments of climate change impacts.