Greening vegetation cools mean and extreme near-surface air temperature in China

Abstract

Satellite observations have shown evident vegetation greening in China during the last two decades. The biophysical effects of vegetation changes on near-surface air temperature (SAT) remain elusive because prior studies focused on the effects on land surface temperature (LST). SAT is more relevant to climate mitigation and adaptation, as this temperature is experienced by humans. Here, we provide the first observational evidence of the greening effects on SAT and SAT extremes in China during 2001–2018 using the ‘space-for-time’ method. The results show a negative SAT sensitivity to greening (–0.35 °C m2 m–2) over China and a cooling effect of −0.08 °C on SAT driven by vegetation greening during the study period. Such a cooling effect is stronger on high SAT extremes, particularly over arid/semiarid areas, where greening could bring an additional cooling of −0.04 °C on the hottest days. An attribution analysis suggests that the main driving factor for the cooling effect of greening is the evapotranspiration change for arid/semiarid regions and the aerodynamic resistance change for humid regions. This study reveals a considerable climate benefit of greening on SAT, which is more concerned with natural and human system health than the greening effects on LST.