Abstract Terrestrial gross primary production (GPP) quantifies the rate of CO2 fixation in ecosystems through photosynthesis. The optimal temperature (Topt) is one of fundamental determinants in the vegetation photosynthesis model (VPM) model that constrains the temperature response of light use efficiency (LUE) under changing environmental conditions. However, the VPM model uses the biome‐specific Topt without considering the spatial variation in Topt. Therefore, this study estimated the global optimal temperature (Topt) from the fluorescence efficiency (ΦF, a proxy of LUE) and adjusted the VPM model by using the spatially resolved Topt. Our results reported that ΦF‐derived Topt is well consistent with LUE‐derived Topt. In addition, the improvement in R2 reached up to 0.05 for sites with a difference between the biome‐specific Topt and ΦF‐derived Topt larger than 5°C. Our results highlight the potential of the adjusted VPM model for studying the global carbon cycle and their responses to the future warming.
Observations from the Little Bunker
Last updated: August 18, 2025 04:13 PM
Atmospheric CO₂
425.4 ppm
+18.4
ppm/year
Atmospheric CH₄
1934.91 ppb
+9.11
ppb/year
Global Temperature
+1.48 °C
Peak: +1.73°C
World Population
8.1 billion
+67
million/year