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Greening of the land surface in the world’s cold regions consistent with recent warming


Global ecosystem function is highly dependent on climate and atmospheric composition, yet ecosystem responses to environmental changes remain uncertain. Cold, high-latitude ecosystems in particular have experienced rapid warming1, with poorly understood consequences2,3,4. Here, we use a satellite-observed proxy for vegetation cover—the fraction of absorbed photosynthetically active radiation5—to identify a decline in the temperature limitation of vegetation in global ecosystems between 1982 and 2012. We quantify the spatial functional response of maximum annual vegetation cover to temperature and show that the observed temporal decline in temperature limitation is consistent with expectations based on observed recent warming. An ensemble of Earth system models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) mischaracterized the functional response to temperature, leading to a large overestimation of vegetation cover in cold regions. We identify a 16.4% decline in the area of vegetated land that is limited by temperature over the past three decades, and suggest an expected large decline in temperature limitation under future warming scenarios. This rapid observed and expected decline in temperature limitation highlights the need for an improved understanding of other limitations to vegetation growth in cold regions3,4,6, such as soil characteristics, species migration, recruitment, establishment, competition and community dynamics.

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Fig. 1: Spatial relationship between temperature and vegetation cover.
Fig. 2: Changes in temperature limitation.
Fig. 3: Observed and predicted changes in F95.
Fig. 4: Current and predicted changes in the relative spatial extent of temperature-limited area of vegetated land.
Fig. 5: ESM estimates of the relationship between maximum vegetation cover and temperature.


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The authors are very grateful to the University of East Anglia Climatic Research Unit for providing the climate data used in this study, the CMIP5 project and ESG Federation for making ESM simulations publicly available, and the Vegetation Remote Sensing and Climate Research group at Boston University for making the satellite fAPAR data available. T.F.K. acknowledges support from NASA Terrestrial Ecology Program IDS Award NNH17AE86I. T.F.K. and W.J.R. were supported by the Director, Office of Science, Office of Biological and Environmental Research of the US Department of Energy under contract DE-AC02-05CH11231 as part of the Reducing Uncertainty in Biogeochemical Interactions through Synthesis and Computation Scientific Focus Area. We thank M. Torn for discussions on the interpretation and implication of the results, and A. Ukkola and I. C. Prentice for early methodological discussions.

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T.F.K. designed and performed the analysis and led the drafting of the manuscript. W.J.R. contributed analysis ideas and participated in drafting the manuscript.

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Correspondence to T. F. Keenan.

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Supplementary figures 1–8, Supplementary Table 1, Supplementary References

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Keenan, T.F., Riley, W.J. Greening of the land surface in the world’s cold regions consistent with recent warming. Nature Clim Change 8, 825–828 (2018).

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