Demographic controls of future global fire risk


Wildfires are an important component of terrestrial ecosystem ecology but also a major natural hazard to societies, and their frequency and spatial distribution must be better understood1. At a given location, risk from wildfire is associated with the annual fraction of burned area, which is expected to increase in response to climate warming1,2,3. Until recently, however, only a few global studies of future fire have considered the effects of other important global environmental change factors such as atmospheric CO2 levels and human activities, and how these influence fires in different regions4,5. Here, we contrast the impact of climate change and increasing atmospheric CO2 content on burned area with that of demographic dynamics, using ensembles of climate simulations combined with historical and projected population changes under different socio-economic development pathways for 1901–2100. Historically, humans notably suppressed wildfires. For future scenarios, global burned area will continue to decline under a moderate emissions scenario, except for low population growth and fast urbanization, but start to increase again from around mid-century under high greenhouse gas emissions. Contrary to common perception, we find that human exposure to wildfires increases in the future mainly owing to projected population growth in areas with frequent wildfires, rather than by a general increase in burned area.

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Figure 1: Eight-ESM ensemble means of simulated global burned area based on varying climate alone, varying climate and CO2 alone, and for all factors including population density.
Figure 2: The probability of low-fire regions becoming fire prone (positive values), or of fire-prone areas changing to a low-fire state (negative values) between 1971–2000 and 2071–2100 based on eight-ESM ensembles.
Figure 3: Two-dimensional histogram plots showing mean fire frequency (fractional burned area, colour scale, in yr−1) and fraction of global burned area (%) by ranges of grass fraction of total (grass and woody) vegetation and population density.

Change history

  • 09 May 2016

    In the version of this Letter originally published, in Figure 1 the labels 'Climate only' and 'Climate and CO2' were assigned the incorrect colours; this has been changed so that the former is now represented by a blue line and the latter by a green line. This has been corrected in all versions of this Letter.


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A.A. and W.K. acknowledge support from the EU FP7 projects PEGASOS (265148) and LUC4C (603542). A.A. also acknowledges support from the Helmholtz Association in the ATMO programme and through its Innovation and Networking fund. W.K. thanks A. Ahlström for providing gridded driving data from the CMIP5 simulations.

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W.K. and A.A. conceived the study, L.J. provided the population scenarios, and W.K. performed simulations and numerical analyses. W.K. and A.A. wrote the first draft of the manuscript. All authors contributed to discussion of results and writing.

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Correspondence to W. Knorr.

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The authors declare no competing financial interests.

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Knorr, W., Arneth, A. & Jiang, L. Demographic controls of future global fire risk. Nature Clim Change 6, 781–785 (2016).

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