Tundra burning in Alaska: Linkages to climatic change and sea ice retreat

[1] Recent climatic warming has resulted in pronounced environmental changes in the Arctic, including shrub cover expansion and sea ice shrinkage. These changes foreshadow more dramatic impacts that will occur if the warming trend continues. Among the major challenges in anticipating these impacts are “surprises” stemming from changes in system components that have remained relatively stable in the historic record. Tundra burning is potentially one such component. Here we report paleoecological evidence showing that recent tundra burning is unprecedented in the central Alaskan Arctic within the last 5000 years. Analysis of lake sediment cores reveals peak values of charcoal accumulation corresponding to the Anaktuvuk River Fire in 2007, with no evidence of other fire events throughout the past five millennia in that area. Atmospheric reanalysis suggests that the fire was favored by exceptionally warm and dry weather conditions in summer and early autumn. Boosted regression tree modeling shows that such conditions also explain 95% of the interannual variability in tundra area burned throughout Alaska over the past 60 years and that the response of tundra burning to climatic warming is nonlinear. These results contribute to an emerging body of evidence suggesting that tundra ecosystems can burn more frequently under suitable climatic and fuel conditions. The Anaktuvuk River Fire coincides with extreme sea ice retreat, and tundra area burned in Alaska is moderately correlated with sea ice extent from 1979 to 2009 (r = −0.43, p = 0.02). Recurrences of large tundra fires as a result of sea ice disappearance may represent a novel manifestation of coupled marine-terrestrial responses to climatic warming.

[1]  T. Swetnam,et al.  Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity , 2006, Science.

[2]  Muyin Wang,et al.  A sea ice free summer Arctic within 30 years? , 2009 .

[3]  M. Torre Jorgenson,et al.  Abrupt increase in permafrost degradation in Arctic Alaska , 2006 .

[4]  Peter Dalgaard,et al.  R Development Core Team (2010): R: A language and environment for statistical computing , 2010 .

[5]  M. Binford,et al.  Calculation and uncertainty analysis of 210Pb dates for PIRLA project lake sediment cores , 1990 .

[6]  E. Kasischke,et al.  Recent changes in the fire regime across the North American boreal region—Spatial and temporal patterns of burning across Canada and Alaska , 2006 .

[7]  Julienne C. Stroeve,et al.  Arctic Sea Ice Extent Plummets in 2007 , 2008 .

[8]  D. Engstrom,et al.  Pronounced climatic variations in Alaska during the last two millennia , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[9]  F. Hu,et al.  Vegetation mediated the impacts of postglacial climate change on fire regimes in the south-central Brooks Range, Alaska , 2008 .

[10]  Karen Willcox,et al.  Kinetics and kinematics for translational motions in microgravity during parabolic flight. , 2009, Aviation, space, and environmental medicine.

[11]  Caitlin E. Buck,et al.  Intcal04 Terrestrial Radiocarbon Age Calibration, 0–26 Cal Kyr BP , 2004, Radiocarbon.

[12]  M. R. Carter,et al.  Terrestrial Ecosystems , 2018, Critical Transitions in Nature and Society.

[13]  Glenn De ' ath.  BOOSTED TREES FOR ECOLOGICAL MODELING AND PREDICTION , 2007 .

[14]  J. Friedman.  Stochastic gradient boosting , 2002 .

[15]  R. Wein.  Frequency and Characteristics of Arctic Tundra Fires , 1976 .

[16]  John G. Dennis,et al.  Tundra Fire Regimes in the Noatak River Watershed, Alaska: 1956-83 , 1985 .

[17]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.

[18]  J Elith,et al.  A working guide to boosted regression trees. , 2008, The Journal of animal ecology.

[19]  E. Kasischke,et al.  Analysis of the patterns of large fires in the boreal forest region of Alaska , 2002 .

[20]  P. Bartlein,et al.  Atmospheric circulation patterns and spatial climatic variations in Beringia , 1998 .

[21]  F. Joos,et al.  Climate and human influences on global biomass burning over the past two millennia , 2008 .

[22]  F. Hu,et al.  An oxygen-isotope record of Holocene climate change in the south-central Brooks Range, Alaska , 2010 .

[23]  N. Fetcher,et al.  Changes in Arctic Tussock Tundra Thirteen Years after Fire , 1984 .

[24]  Marika M. Holland,et al.  Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss , 2008 .

[25]  References , 1971 .

[26]  John E. Walsh,et al.  IMPACTS OF LARGE‐SCALE ATMOSPHERIC–OCEAN VARIABILITY ON ALASKAN FIRE SEASON SEVERITY , 2005 .

[27]  M. Holland,et al.  The emergence of surface-based Arctic amplification , 2008 .

[28]  Christopher I. Roos,et al.  Fire in the Earth System , 2009, Science.

[29]  Benjamin M. Jones,et al.  Fire Behavior, Weather, and Burn Severity of the 2007 Anaktuvuk River Tundra Fire, North Slope, Alaska , 2009 .

[30]  F. Hu,et al.  Frequent Fires in Ancient Shrub Tundra: Implications of Paleorecords for Arctic Environmental Change , 2008, PloS one.

[31]  U. Krähenbühl,et al.  Postglacial vegetational and fire history: pollen, plant macrofossil and charcoal records from two Alaskan lakes , 2006 .

[32]  W. Oswald,et al.  Effects of sample mass and macrofossil type on radiocarbon dating of arctic and boreal lake sediments , 2005 .

[33]  A. Fischlin,et al.  Ecosystems, their properties, goods and services , 2007 .

[34]  M. Moritz,et al.  Environmental controls on the distribution of wildfire at multiple spatial scales , 2009 .

[35]  F. Chapin,et al.  Permafrost and the Global Carbon Budget , 2006, Science.

[36]  S. Orel.  Ecosystem feedbacks and cascade processes: understanding their role in the responses of Arctic and alpine ecosystems to environmental change , 2009 .

[37]  C. Justice,et al.  Global distribution and seasonality of active fires as observed with the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) sensors , 2006 .

[38]  M. Sturm,et al.  The evidence for shrub expansion in Northern Alaska and the Pan‐Arctic , 2006 .

[39]  Stephen Sitch,et al.  Numerical Terradynamic Simulation Group 1-2007 ASSESSING THE CARBON BALANCE OF CIRCUMPOLAR ARCTIC TUNDRA USING REMOTE SENSING AND PROCESS MODELING , 2018 .

[40]  Greg Ridgeway,et al.  Generalized Boosted Models: A guide to the gbm package , 2006 .

[41]  Leslie A. Viereck,et al.  PAT"TERNS OF VEGETATION RECOVERY AFT"'ER TUNDRA FIRES IN NORTHWESTERN ALASKA, U.S.A. , 1987 .

[42]  The Circumpolar Arctic vegetation map Errata : 1 ) , 2005 .

[43]  Donald A. Walker,et al.  The Circumpolar Arctic vegetation map , 2005 .

[44]  Kenji Yoshikawa,et al.  Physical short‐term changes after a tussock tundra fire, Seward Peninsula, Alaska , 2007 .

[45]  J. Lynch,et al.  Forest fire and climate change in western North America: insights from sediment charcoal records , 2007 .

[46]  F. Chapin,et al.  Role of Land-Surface Changes in Arctic Summer Warming , 2005, Science.

[47]  Kyle Joly,et al.  Slow Recovery of Lichen on Burned Caribou Winter Range in Alaska Tundra: Potential Influences of Climate Warming and Other Disturbance Factors , 2008 .

[48]  F. Chapin.  Warming Role of Land-Surface Changes in Arctic Summer , 2007 .