Increased light-use efficiency in northern terrestrial ecosystems indicated by CO2 and greening observations

Rebecca T. Thomas*, Iain Colin Prentice, Heather Graven, Philippe Ciais, Joshua B. Fisher, Daniel J. Hayes, Maoyi Huang, Deborah N. Huntzinger, Akihiko Ito, Atul Jain, Jiafu Mao, Anna M. Michalak, Shushi Peng, Benjamin Poulter, Daniel M. Ricciuto, Xiaoying Shi, Christopher Schwalm, Hanqin Tian, Ning Zeng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


Observations show an increasing amplitude in the seasonal cycle of CO2 (ASC) north of 45°N of 56 ± 9.8% over the last 50 years and an increase in vegetation greenness of 7.5–15% in high northern latitudes since the 1980s. However, the causes of these changes remain uncertain. Historical simulations from terrestrial biosphere models in the Multiscale Synthesis and Terrestrial Model Intercomparison Project are compared to the ASC and greenness observations, using the TM3 atmospheric transport model to translate surface fluxes into CO2 concentrations. We find that the modeled change in ASC is too small but the mean greening trend is generally captured. Modeled increases in greenness are primarily driven by warming, whereas ASC changes are primarily driven by increasing CO2. We suggest that increases in ecosystem-scale light use efficiency (LUE) have contributed to the observed ASC increase but are underestimated by current models. We highlight potential mechanisms that could increase modeled LUE.

Original languageEnglish
Pages (from-to)11,339-11,349
Number of pages11
JournalGeophysical Research Letters
Issue number21
Publication statusPublished - 16 Nov 2016
Externally publishedYes


  • carbon cycle
  • greening
  • light use efficiency
  • NPP
  • terrestrial biosphere model


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