Global environmental change is rapidly altering the dynamics of terrestrial vegetation, with consequences for the functioning of the Earth system and provision of ecosystem services1,2. Yet how global vegetation is responding to the changing environment is not well established. Here we use three long-term satellite leaf area index (LAI) records and ten global ecosystem models to investigate four key drivers of LAI trends during 1982–2009. We show a persistent and widespread increase of growing season integrated LAI (greening) over 25% to 50% of the global vegetated area, whereas less than 4% of the globe shows decreasing LAI (browning). Factorial simulations with multiple global ecosystem models suggest that CO2 fertilization effects explain 70% of the observed greening trend, followed by nitrogen deposition (9%), climate change (8%) and land cover change (LCC) (4%). CO2 fertilization effects explain most of the greening trends in the tropics, whereas climate change resulted in greening of the high latitudes and the Tibetan Plateau. LCC contributed most to the regional greening observed in southeast China and the eastern United States. The regional effects of unexplained factors suggest that the next generation of ecosystem models will need to explore the impacts of forest demography, differences in regional management intensities for cropland and pastures, and other emerging productivity constraints such as phosphorus availability.

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This study was supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant XDB03030404), National Basic Research Program of China (Grant 2013CB956303), National Natural Science Foundation of China (Grant 41530528), the 111 Project (Grant B14001), and the European Research Council Synergy grant ERC-SyG-610028 IMBALANCE-P. We thank all people and institutions who provided data used in this study, in particular, the TRENDY modelling group. R.B.M. is funded by NASA Earth Science. J.G.C. is grateful for support from the Australian Climate Change Science Program. A.A. and T.A.M.P. acknowledge support through EC FP7 grants LUC4C (Grant 603542) and EMBRACE (Grant 282672) and the Helmholtz Association ATMO programme, Y.W. acknowledges CSIRO strategic funding for CABLE science, E.K. was funded by ERTDF (S10) from the Ministry of Environment, Japan. J.M. is supported by the US Department of Energy (DOE), Office of Science, Biological and Environmental Research. Oak Ridge National Laboratory is managed by UT-BATTELLE for DOE under contract DE-AC05-00OR22725. B.D.S. is supported by the Swiss National Science Foundation and FP7 funding through project EMBRACE (282672).

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  1. Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, CAS Center for Excellence in Tibetan Plateau Earth Science, Chinese Academy of Sciences, Beijing 100085, China

    • Zaichun Zhu
    •  & Shilong Piao
  2. Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China

    • Zaichun Zhu
    • , Shilong Piao
    • , Mengtian Huang
    • , Zhenzhong Zeng
    • , Philippe Ciais
    • , Yue Li
    • , Xu Lian
    • , Yongwen Liu
    • , Shushi Peng
    • , Xuhui Wang
    •  & Hui Yang
  3. Department of Earth and Environment, Boston University, Boston, Massachusetts 02215, USA

    • Ranga B. Myneni
  4. Global Carbon Project, CSIRO Oceans and Atmosphere, GPO Box 3023, Canberra, Australian Capital Territory 2601, Australia

    • Josep G. Canadell
  5. Laboratoire des Sciences du Climat et de l’Environnement (LSCE), CEA CNRS UVSQ, 91191 Gif Sur Yvette, France

    • Philippe Ciais
    •  & Nicolas Viovy
  6. College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QF, UK

    • Stephen Sitch
  7. College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, UK

    • Pierre Friedlingstein
  8. Institute of Meteorology and Climate Research, Atmospheric Environmental Research, Karlsruhe Institute of Technology, 82467 Garmisch-Partenkirchen, Germany

    • Almut Arneth
    •  & Thomas A. M. Pugh
  9. State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China

    • Chunxiang Cao
  10. CSIRO Land and Water, Black Mountain, Canberra, Australian Capital Territory 2601, Australia

    • Lei Cheng
  11. Institute of Applied Energy (IAE), Minato-ku, Tokyo 105-0003, Japan

    • Etsushi Kato
  12. Earth Sciences Division, Lawrence Berkeley National Lab, 1 Cyclotron Road, Berkeley, California 94720, USA

    • Charles Koven
  13. LREIS, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China

    • Ronggao Liu
  14. Climate Change Science Institute and Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

    • Jiafu Mao
  15. College of Resources Science & Technology, State Key Laboratory of Earth Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China

    • Yaozhong Pan
  16. CSIC, Global Ecology Unit CREAF-CEAB-UAB, Cerdanyola del Vallès, 08193 Catalonia, Spain

    • Josep Peñuelas
  17. CREAF, Cerdanyola del Vallès, 08193 Catalonia, Spain

    • Josep Peñuelas
  18. Montana State University, Institute on Ecosystems and the Department of Ecology, Bozeman, Montana 59717, USA

    • Benjamin Poulter
  19. School of Geography, Earth and Environmental Science, University of Birmingham, Birmingham B15 2TT, UK

    • Thomas A. M. Pugh
  20. Department of Life Sciences, Imperial College London, Silwood Park, Ascot SL5 7PY, UK

    • Benjamin D. Stocker
  21. Climate and Environmental Physics, and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland

    • Benjamin D. Stocker
  22. CSIRO Oceans and Atmosphere, PMB #1, Aspendale, Victoria 3195, Australia

    • Yingping Wang
  23. State Key Laboratory of Remote Sensing Science, School of Geography, Beijing Normal University, Beijing 100875, China

    • Zhiqiang Xiao
  24. Max-Planck-Institut für Biogeochemie, PO Box 600164, Hans-Knöll-Str. 10, 07745 Jena, Germany

    • Sönke Zaehle
  25. Department of Atmospheric and Oceanic Science, University of Maryland, College Park, Maryland 20742, USA

    • Ning Zeng


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S.Piao, R.B.M. and Z.Zhu designed the study. Z.Zhu performed the analysis. Z.Zhu, S.Piao, J.G.C., P.C. and R.B.M. drafted the paper. Z.Zhu, M.H., Z.Zeng, C.C., Y.Liu, H.Y., X.W., X.L., Y.P., Y.Li, R.L. and Z.X. collected data and prepared figures. S.S., P.F., A.A., B.D.S., B.P., C.K., E.K., J.M., J.P., L.C., N.V., N.Z., S.Peng, S.Z., T.A.M.P., and Y.W. ran the model simulations. All authors contributed to the interpretation of the results and to the text.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Shilong Piao.

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