With the Alberta wildfire in the headlines comes this study from the University of Montana saying that the risk of Alaskan wildfires will increase four-fold this century with future climate change.
From the University of Montana
Climate change is melting glaciers, reducing sea-ice cover and increasing wildlife activity – with some of the most dramatic impacts occurring in the northern high latitudes.
New research by University of Montana affiliate scientist Adam Young and UM fire ecology Associate Professor Philip Higuera projects an increased probability of fires occurring in Alaskan boreal forest and tundra under a warmer, drier climate. Their work recently was published in the journal Ecography.
The paper titled “Climatic thresholds shape northern high-latitude fire regimes and imply vulnerability to future climate change” in the journal Ecography.
Young, also a doctoral candidate at the University of Idaho, projects that by the end of this century the probability of burning in many high-latitude ecosystems in Alaska will be up to four times higher than seen in recent decades. Tundra and the forest-tundra boundary, which have not burned often in the past, are particularly sensitive to projected changes in temperature and moisture.
“We looked at the location of wildfires across Alaska during the past 60 years and, not surprisingly, found that they were most common in regions with warm, dry summers,” Young said. “The more interesting result of our work is the emergence of a distinct temperature threshold that separates areas that have and have not burned in recent decades. Above this threshold, we see a sharp increase in the likelihood that a fire will occur in a region.”
The research highlights that regions crossing this temperature threshold as a result of climate change are the most vulnerable to increased burning.
Boreal forests and tundra store an estimated 50 percent of Earth’s soil carbon. Increased fire activity could release more stored carbon into the atmosphere, which would increase atmospheric greenhouse gas concentrations and potentially have global implications.
The researchers used a database of fire history, which has been maintained by the federal government since 1950, and combined it with information on vegetation and climate to develop statistical models that predict the most important controls of historic fire activity.
Young and Higuera expect their results will help scientists and mangers better understand when and where fires occur in northern high latitudes and how fire activity will change in the future.
The research was funded by the National Science Foundation, NASA and the Joint Fire Science Program, and it includes scientists from the University of Illinois and the environmental consulting firm Neptune and Company Inc.
Boreal forests and arctic tundra cover 33% of global land surface and store an estimated 50% of total soil carbon. Because wildfire is a key driver of terrestrial carbon cycling, increasing fire activity in these ecosystems would likely have global implications. To anticipate potential spatiotemporal variability in fire-regime shifts, we modeled the spatially explicit 30-yr probability of fire occurrence as a function of climate and landscape features (i.e., vegetation and topography) across Alaska. Boosted regression tree (BRT) models captured the spatial distribution of fire across boreal forest and tundra ecoregions (AUC from 0.63-0.78 and Pearson correlations between predicted and observed data from 0.54-0.71), highlighting summer temperature and annual moisture availability as the most influential controls of historical fire regimes. Modeled fire-climate relationships revealed distinct thresholds to fire occurrence, with a nonlinear increase in the probability of fire above an average July temperature of 13.4 °C and below an annual moisture availability (i.e., P-PET) of approximately 150 mm. To anticipate potential fire-regime responses to 21st-century climate change, we informed our BRTs with Coupled Model Intercomparison Project Phase 5 climate projections under the RCP 6.0 scenario. Based on these projected climatic changes alone (i.e., not accounting for potential changes in vegetation), our results suggest an increasing probability of wildfire in Alaskan boreal forest and tundra ecosystems, but of varying magnitude across space and throughout the 21st century. Regions with historically low flammability, including tundra and the forest-tundra boundary, are particularly vulnerable to climatically induced changes in fire activity, with up to a fourfold increase in the 30-yr probability of fire occurrence by 2100. Our results underscore the climatic potential for novel fire regimes to develop in these ecosystems, relative to the past 6,000-35,000 years, and spatial variability in the vulnerability of wildfire regimes and associated ecological processes to 21st-century climate change.
Adam M. Young, Philip E. Higuera, Paul A. Duffy3 and Feng Sheng Hu; Climatic thresholds shape northern high-latitude fire regimes and imply vulnerability to future climate change; Ecography, DOI: 10.1111/ecog.02205
University of Montana news release.