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Global pyrogeography: the current and future distribution of wildfire.

Krawchuk MA, Moritz MA, Parisien MA, Van Dorn J, Hayhoe K - PLoS ONE (2009)

Bottom Line: Based on current conditions, our results illustrate how the availability of resources to burn and climate conditions conducive to combustion jointly determine why some parts of the world are fire-prone and others are fire-free.In contrast to any expectation that global warming should necessarily result in more fire, we find that regional increases in fire probabilities may be counter-balanced by decreases at other locations, due to the interplay of temperature and precipitation variables.Despite this net balance, our models predict substantial invasion and retreat of fire across large portions of the globe.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America.

ABSTRACT
Climate change is expected to alter the geographic distribution of wildfire, a complex abiotic process that responds to a variety of spatial and environmental gradients. How future climate change may alter global wildfire activity, however, is still largely unknown. As a first step to quantifying potential change in global wildfire, we present a multivariate quantification of environmental drivers for the observed, current distribution of vegetation fires using statistical models of the relationship between fire activity and resources to burn, climate conditions, human influence, and lightning flash rates at a coarse spatiotemporal resolution (100 km, over one decade). We then demonstrate how these statistical models can be used to project future changes in global fire patterns, highlighting regional hotspots of change in fire probabilities under future climate conditions as simulated by a global climate model. Based on current conditions, our results illustrate how the availability of resources to burn and climate conditions conducive to combustion jointly determine why some parts of the world are fire-prone and others are fire-free. In contrast to any expectation that global warming should necessarily result in more fire, we find that regional increases in fire probabilities may be counter-balanced by decreases at other locations, due to the interplay of temperature and precipitation variables. Despite this net balance, our models predict substantial invasion and retreat of fire across large portions of the globe. These changes could have important effects on terrestrial ecosystems since alteration in fire activity may occur quite rapidly, generating ever more complex environmental challenges for species dispersing and adjusting to new climate conditions. Our findings highlight the potential for widespread impacts of climate change on wildfire, suggesting severely altered fire regimes and the need for more explicit inclusion of fire in research on global vegetation-climate change dynamics and conservation planning.

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The observed and modeled distribution of fire under current conditions.(A) Cumulative counts of fire activity detected by the Along Track Scanning Radiometer (ATSR) around the world at a resolution of 100 km over 10 years. (B) The same fire data classified to represent fire-prone (orange) and fire-free (yellow) parts of the world; note that areas of white within terrestrial boundaries were clipped from the analyses to match climate data. (C) Mean of normalized relative probability of fire (nPc) for ten FIRENPP sub-models of fire-prone parts of the world under current conditions. (D) Mean of normalized relative probability of fire (nPc) for ten FIREnoNPP sub-models of fire-prone parts of the world under current conditions.
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pone-0005102-g001: The observed and modeled distribution of fire under current conditions.(A) Cumulative counts of fire activity detected by the Along Track Scanning Radiometer (ATSR) around the world at a resolution of 100 km over 10 years. (B) The same fire data classified to represent fire-prone (orange) and fire-free (yellow) parts of the world; note that areas of white within terrestrial boundaries were clipped from the analyses to match climate data. (C) Mean of normalized relative probability of fire (nPc) for ten FIRENPP sub-models of fire-prone parts of the world under current conditions. (D) Mean of normalized relative probability of fire (nPc) for ten FIREnoNPP sub-models of fire-prone parts of the world under current conditions.

Mentions: Global studies examining how the distribution of fire might change in the future are necessary to establish the potential impacts of climate change on vegetation and ecosystems. Local and regional studies have projected both increases and decreases in future fire activity, [25]–[27] however we lack the quantitative estimates needed to understand what the net effect might be across a warmer planet. For these reasons, our first goal in this global pyrogeography was to characterize the observed global fire occurrence pattern (Figure 1) with an ensemble of multivariate statistical generalized additive models (GAMs) combining existing fire occurrence, climate, net primary productivity (NPP), and ignition data. Since many parts of the globe are fire-free because they have little or no vegetation to burn, it is informative to distinguish between areas that do not burn due to limiting consumable resources versus limiting environmental conditions. To address this issue, we included global vegetation distribution as an explicit metric for resource availability in one ensemble of models (FIRENPP), allowing climate to describe additional variability in fire-conducive conditions. We contrasted this approach to another ensemble of models (FIREnoNPP) where climate variables alone were used to describe both resources and conditions needed for fire. Our results provide a novel multivariate framework to describe where we currently see wildfire across the planet. We then apply these models to future climate scenarios, providing a first estimate of potential changes in the global distribution of fire. The climate change projections presented here are based on simulations from the Geophysical Fluid Dynamics Laboratory Climate Model 2.1 (GFDL CM2.1). Our intent is to demonstrate the scope of changes that could occur given anticipated climates under mid-high (A2), and lower (B1) emissions scenarios proposed by the IPCC Special Report on Emission Scenarios [28].


Global pyrogeography: the current and future distribution of wildfire.

Krawchuk MA, Moritz MA, Parisien MA, Van Dorn J, Hayhoe K - PLoS ONE (2009)

The observed and modeled distribution of fire under current conditions.(A) Cumulative counts of fire activity detected by the Along Track Scanning Radiometer (ATSR) around the world at a resolution of 100 km over 10 years. (B) The same fire data classified to represent fire-prone (orange) and fire-free (yellow) parts of the world; note that areas of white within terrestrial boundaries were clipped from the analyses to match climate data. (C) Mean of normalized relative probability of fire (nPc) for ten FIRENPP sub-models of fire-prone parts of the world under current conditions. (D) Mean of normalized relative probability of fire (nPc) for ten FIREnoNPP sub-models of fire-prone parts of the world under current conditions.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2662419&req=5

pone-0005102-g001: The observed and modeled distribution of fire under current conditions.(A) Cumulative counts of fire activity detected by the Along Track Scanning Radiometer (ATSR) around the world at a resolution of 100 km over 10 years. (B) The same fire data classified to represent fire-prone (orange) and fire-free (yellow) parts of the world; note that areas of white within terrestrial boundaries were clipped from the analyses to match climate data. (C) Mean of normalized relative probability of fire (nPc) for ten FIRENPP sub-models of fire-prone parts of the world under current conditions. (D) Mean of normalized relative probability of fire (nPc) for ten FIREnoNPP sub-models of fire-prone parts of the world under current conditions.
Mentions: Global studies examining how the distribution of fire might change in the future are necessary to establish the potential impacts of climate change on vegetation and ecosystems. Local and regional studies have projected both increases and decreases in future fire activity, [25]–[27] however we lack the quantitative estimates needed to understand what the net effect might be across a warmer planet. For these reasons, our first goal in this global pyrogeography was to characterize the observed global fire occurrence pattern (Figure 1) with an ensemble of multivariate statistical generalized additive models (GAMs) combining existing fire occurrence, climate, net primary productivity (NPP), and ignition data. Since many parts of the globe are fire-free because they have little or no vegetation to burn, it is informative to distinguish between areas that do not burn due to limiting consumable resources versus limiting environmental conditions. To address this issue, we included global vegetation distribution as an explicit metric for resource availability in one ensemble of models (FIRENPP), allowing climate to describe additional variability in fire-conducive conditions. We contrasted this approach to another ensemble of models (FIREnoNPP) where climate variables alone were used to describe both resources and conditions needed for fire. Our results provide a novel multivariate framework to describe where we currently see wildfire across the planet. We then apply these models to future climate scenarios, providing a first estimate of potential changes in the global distribution of fire. The climate change projections presented here are based on simulations from the Geophysical Fluid Dynamics Laboratory Climate Model 2.1 (GFDL CM2.1). Our intent is to demonstrate the scope of changes that could occur given anticipated climates under mid-high (A2), and lower (B1) emissions scenarios proposed by the IPCC Special Report on Emission Scenarios [28].

Bottom Line: Based on current conditions, our results illustrate how the availability of resources to burn and climate conditions conducive to combustion jointly determine why some parts of the world are fire-prone and others are fire-free.In contrast to any expectation that global warming should necessarily result in more fire, we find that regional increases in fire probabilities may be counter-balanced by decreases at other locations, due to the interplay of temperature and precipitation variables.Despite this net balance, our models predict substantial invasion and retreat of fire across large portions of the globe.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America.

ABSTRACT
Climate change is expected to alter the geographic distribution of wildfire, a complex abiotic process that responds to a variety of spatial and environmental gradients. How future climate change may alter global wildfire activity, however, is still largely unknown. As a first step to quantifying potential change in global wildfire, we present a multivariate quantification of environmental drivers for the observed, current distribution of vegetation fires using statistical models of the relationship between fire activity and resources to burn, climate conditions, human influence, and lightning flash rates at a coarse spatiotemporal resolution (100 km, over one decade). We then demonstrate how these statistical models can be used to project future changes in global fire patterns, highlighting regional hotspots of change in fire probabilities under future climate conditions as simulated by a global climate model. Based on current conditions, our results illustrate how the availability of resources to burn and climate conditions conducive to combustion jointly determine why some parts of the world are fire-prone and others are fire-free. In contrast to any expectation that global warming should necessarily result in more fire, we find that regional increases in fire probabilities may be counter-balanced by decreases at other locations, due to the interplay of temperature and precipitation variables. Despite this net balance, our models predict substantial invasion and retreat of fire across large portions of the globe. These changes could have important effects on terrestrial ecosystems since alteration in fire activity may occur quite rapidly, generating ever more complex environmental challenges for species dispersing and adjusting to new climate conditions. Our findings highlight the potential for widespread impacts of climate change on wildfire, suggesting severely altered fire regimes and the need for more explicit inclusion of fire in research on global vegetation-climate change dynamics and conservation planning.

Show MeSH
Related in: MedlinePlus