Abstract Different trends were found for global terrestrial gross primary production (GPP) based on different light‐use‐efficiency (LUE) models. None of these models considered chlorophyll content as a driving variable, although chlorophyll content is essential for capturing light energy in the photosynthetic process. Here, we examine the effects of the MERIS terrestrial chlorophyll index (MTCI, a proxy for chlorophyll content) on GPP using a justified LUE model that accounts for the effects of chlorophyll on photosynthesis. We find a significant increase in MTCI on 11% of the globe, whereas 15% of the globe shows a decrease in MTCI (p < 0.05) from 2003 to 2011. MTCI is the most important variable influencing GPP variations on more than 55% of the globe, and consequently global GPP shows an insignificant trend. The study suggests that the limitation of terrestrial chlorophyll on GPP could be significant but has been neglected in previous estimates.
Observations from the Little Bunker
Last updated: November 30, 2025 04:25 AM
Atmospheric CO₂
426.8 ppm
+18.1
ppm/year
Atmospheric CH₄
1927.61 ppb
+2.73
ppb/year
Global Temperature
+1.48 °C
Peak: +1.73°C
World Population
8.1 billion
+67
million/year