Global temperature is increasing, especially over northern lands (>50° N), owing to positive feedbacks1. As this increase is most pronounced in winter, temperature seasonality (ST)—conventionally defined as the difference between summer and winter temperatures—is diminishing over time2, a phenomenon that is analogous to its equatorward decline at an annual scale. The initiation, termination and performance of vegetation photosynthetic activity are tied to threshold temperatures3. Trends in the timing of these thresholds and cumulative temperatures above them may alter vegetation productivity, or modify vegetation seasonality (SV), over time. The relationship between ST and SV is critically examined here with newly improved ground and satellite data sets. The observed diminishment of ST and SV is equivalent to 4° and 7° (5° and 6°) latitudinal shift equatorward during the past 30 years in the Arctic (boreal) region. Analysis of simulations from 17 state-of-the-art climate models4 indicates an additional STdiminishment equivalent to a 20° equatorward shift could occur this century. How SV will change in response to such large projected ST declines and the impact this will have on ecosystem services5 are not well understood. Hence the need for continued monitoring6 of northern lands as their seasonal temperature profiles evolve to resemble thosefurther south.

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This work was financially supported by the NASA Earth Science Division. We thank CRU, NSIDC, NASA MODIS Project, CAVM team and the CMIP5 climate modelling groups (listed in Supplementary Table S7) for making their data available. The authors thank U. S. Bhatt, H. E. Epstein, G. R. North, M. K. Raynolds, A. R. Stine, G. Schmidt and D. A. Walker for their comments on various parts of this article.

Author information

Author notes

    • L. Xu
    •  & R. B. Myneni

    These authors contributed equally to this work


  1. Department of Earth and Environment, Boston University, Boston, Massachusetts 02215, USA

    • L. Xu
    • , R. B. Myneni
    • , Z. Zhu
    • , J. Bi
    •  & B. T. Anderson
  2. Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775, USA

    • F. S. Chapin III
    •  & E. S. Euskirchen
  3. Royal Swedish Academy of Sciences, PO Box 50005, 104 05 Stockholm, Sweden

    • T. V. Callaghan
  4. Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK

    • T. V. Callaghan
  5. Biospheric Sciences Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA

    • J. E. Pinzon
    •  & C. J. Tucker
  6. Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-UVSQ, 91191 Gif sur Yvette, Cedex, France

    • P. Ciais
  7. Norwegian Institute for Nature Research, Fram-High North Research Center for Climate and the Environment, N-9296 Tromsø, Norway

    • H. Tømmervik
  8. Arctic Centre, University of Lapland, FI-96101 Rovaniemi, Finland

    • B. C. Forbes
  9. Department of Ecology, Peking University, Beijing 100871, China

    • S. L. Piao
  10. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China

    • S. L. Piao
  11. Bay Area Environmental Research Institute, NASA Ames Research Center, Moffett Field, California 94035, USA

    • S. Ganguly
  12. NASA Advanced Supercomputing Division, Ames Research Center, Moffett Field, California 94035, USA

    • R. R. Nemani
  13. The Woods Hole Research Center, Woods Hole, Falmouth, Massachusetts 02540, USA

    • S. J. Goetz
    •  & P. S. A. Beck
  14. Department of Environmental Sciences, Huxley College, Western Washington University, Bellingham, Washington 98225, USA

    • A. G. Bunn
  15. State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China

    • C. Cao
  16. School of Resource and Environment, University of Electronic Science and Technology of China, Chengdu, Sichuan 611731, China

    • C. Cao
  17. National Snow and Ice Data Center, University of Colorado, Boulder, Colorado 80309, USA

    • J. C. Stroeve


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The analysis was performed by X.L., R.B.M, Z.Z and J.B. All authors contributed with ideas, writing and discussions.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to L. Xu or R. B. Myneni.

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