EGU26-4870, updated on 13 Mar 2026
https://doi.org/10.5194/egusphere-egu26-4870
EGU General Assembly 2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
Oral | Thursday, 07 May, 09:55–10:05 (CEST)
 
Room 1.14
Atmospheric Dryness Dominates Afternoon Depression of Global Terrestrial Photosynthesis
Yue Liu1,2, Josep Peñuelas3,4, Alessandro Cescatti5, Yongguang Zhang1,2,6, and Zhaoying Zhang1,2,6
Yue Liu et al.
  • 1International Institute for Earth System Sciences, Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing University, Nanjing, China,
  • 2Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, Key Laboratory for Land Satellite Remote Sensing Applications of Ministry of Natural Resources, School of Geography and Ocean Science, Nanjing University, Nanjing, China
  • 3CSIC, Global Ecology Unit CREAF‐CSIC‐UAB, Bellaterra, Spain
  • 4CREAF, Cerdanyola del Vallès, Spain
  • 5European Commission, Joint Research Centre (JRC), Ispra, Italy
  • 6International Joint Carbon Neutrality Laboratory, Nanjing University, Nanjing, China

Satellite observations reveal a widespread afternoon depression of photosynthesis globally.Utilizing satellite observations and eddy covariance tower‐based observations worldwide, we investigated the impact of climate factors on the diurnal patterns of ecosystem gross primary production (GPP). Our analysis revealed that the increase in vapor pressure deficit (VPD) shifts the diurnal peak of GPP activity to earlier morning hours, particularly in drylands and areas with short vegetation. After disentangling the strong correlations among VPD, temperature, and soil moisture, we unraveled that VPD emerges as the dominant driver contributing to the widespread afternoon depression of photosynthesis in terrestrial vegetation globally. However, Earth System Models (ESMs) systematically underestimate the significant role of VPD in regulating photosynthesis. Eight out of 10 ESMs exhibited a clear afternoon increase in photosynthesis, which was attributed to temperature. Our findings emphasize the need to enhance the negative effects of VPD on diurnal photosynthesis in ESMs

How to cite: Liu, Y., Peñuelas, J., Cescatti, A., Zhang, Y., and Zhang, Z.: Atmospheric Dryness Dominates Afternoon Depression of Global Terrestrial Photosynthesis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4870, https://doi.org/10.5194/egusphere-egu26-4870, 2026.