Lightning Sparking More Boreal Forest Fires

Our Research Brief this month covers a new NASA-funded study led by Sander Veraverbeke of Vrije Universiteit  in Amsterdam which found lightning storms to be a main driver of recent large fire seasons in Alaska and Canada.  Results of the study are published in the July, 2017 issue of Nature Climate Change.


 July 2017 Nature Climate Change

MODIS (Moderate-Resolution Imaging Spectroradiometer) satellite images and data from ground-based lightning networks were employed to study fire ignitions. Sander’s analysis found increases of between two and five percent a year in the number of lightning-ignited fires since 1975. Veraverbeke said that the observed trends are consistent with climate change, with higher temperatures linked to both more burning and more thunderstorms.

Study co-author Brendan Rogers at Woods Hole Research Center in Massachusetts says these trends are likely to continue. “We expect an increasing number of thunderstorms, and hence fires, across the high latitudes in the coming decades as a result of climate change.” This is confirmed in the study by different climate model outputs.

Charles Miller of NASA’s Jet Propulsion Laboratory in California, another co-author, said while data from Alaska’s agency lightning networks were critical to this study, it is challenging to use these data to verify trends because of continuing network upgrades. “A spaceborne sensor that provides lightning data that can be linked with fire dynamics would be a major step forward,” he said. Such a sensor exists already– NASA’s spaceborne Optical Transient Detector –but it’s geostationary orbit limits its utility for high latitudes.

The researchers found that the fires are creeping farther north, near the transition from boreal forests to Arctic tundra. “In these high-latitude ecosystems, permafrost soils store large amounts of carbon that become vulnerable after fires pass through,” said co-author James Randerson of the University of California, Irvine. “Exposed mineral soils after tundra fires also provide favorable seedbeds for trees migrating north under a warmer climate.”

The Alaska Fire Science Consortium at the University of Alaska, Fairbanks, also participated in the study, and provides this 2-page Research Brief executive summary.


Citation: Veraverbeke, S., B.M. Rogers, M.L. Goulden, R.R. Jandt, C.E. Miller, E.B. Wiggins and J.T. Randerson. Lightning as a major driver of recent large fire years in North American boreal forests. Nature Climate Change 7: 529–534 (2017). DOI: 10.1038/nclimate3329

Future Fire Costs in Alaska

April Melvin of EPA’s National Climate Change Division has spent some time in the field in Alaska. In a just-released publication her research team takes a look at how firefighting costs in Alaska are likely to change through the next several decades.


“Pumpkin” water bladder preparing burnout on the Chicken fire 2004. Photo by Cyle Wold, USFS-PNW.

They use the ALFRESCO  model developed at UAF, which simulates fire ignition and spread (annual timesteps) under different climate projections in 100-km grid cells. Read their paper (citation below) for all the details, but in a nutshell they found:  1) it’s hard to nail down precise fire cost records in the multi-jurisdictional setting!  2) Fire costs go up in the future and the biggest expenditures will be in the Full fire protection option.   3) by 2030, predicted federal fire suppression costs (not including base–support and pre-suppression) will average $27-47M annually under the RCP 4.5 (moderate emissions) climate projection. That compares to about $31M on average from 2002-2013.  Adding in state costs boosts this to about $116M total firefighting cost for Alaska assuming the state costs are still roughly 68% of the total cost.  Again this does not include base operating costs.  The paper provides some good analysis for fire protection agencies to take to the bank.  Or at least to the Legislature!

Citation: Melvin, A.M., Murray, J., Boehlert, B. et al. 2017. Estimating wildfire response costs in Alaska’s changing climate.   Climate Change:  p 1-13.  doi:10.1007/s10584-017-1923-2.

Fire’s Role in a Broadleaf Future for Alaska?

As climate warming brings more wildfire to the North, scientists and citizens wonder how the landscape will be transformed.  Will forests continue their 2000’s-era trend toward less spruce and more hardwoods, catalyzed by larger fires and more frequent burning?  If so, that might slow down the trend for larger and more intense fires. However, will hotter summers with more effective drying lead to increased fire re-entry into the early successional hardwoods, making them less strategic barriers for fire protection? A research team modeling the former question just unveiled an interactive web tool to model forest changes under various future climate scenarios (Feb. 1 webinar recording available HERE).  With the new web tool, funded by JFSP,  Paul Duffy and Courtney Schultz will be working with fire managers in Alaska to look at fire occurrence and cost in the future.  Try it for yourself at

Photo by USFS, PNW (2004).

As for the second question–will it be harder for hardwoods to resist fire–a recent paper in Ecosphere (Barrett et al. 2016) is one of the first published studies to look for an answer.  AFSC highlights that work with a Research Brief this month: A Deeper Look at Drivers of Fire Activity, Re-burns, and Unburned Patches in Alaska’s Boreal Forest.  Check out all our Research Briefs in our web Library.

Citation: Barrett, K, T. Loboda, AD McGuire, H. Genet, E. Hoy, and E. Kasischke. 2016. Static and dynamic controls on fire activity at moderate spatial and temporal scales in the Alaskan boreal forest. Ecosphere 7(11):e01572. 10.1002/ecs2.1572

Climate analogs to see the future today

The subject of a new study (and a recent AFSC webinar by Sean Parks of the USFS Rocky Mountain Research Station) introduces a novel way to look at fire regime changes through time over a landscape using the idea of “climate analogs”.  We’ve all seen maps showing future changes in temperature and precipitation based on climate projection models. Spatial analysis can locate a “future” climate analog for any pixel on a map using projections of variables like temperature, precipitation, or modeled evapotranspiration. Parks et al. 2016 provide a way to “look next door to see the future”, i.e. our pixel or region of interest, may be expected to show a fire return interval, burn severity, etc. similar to that now reflected in its analog which has those climate characteristics today.  If the average annual temperature in Fairbanks was 30⁰F in 2015, for example, we could map the nearest points that may have similar temperatures by 2085—possibly at higher elevations around Fairbanks. If a “path of least resistance” with respect to skirting areas that may have way different temperatures due to topographic features is added, you get a figure kind of like the one below from Yellowstone park (Dobrowski and Parks 2016). The authors have used the method to look at future availability of wildlife habitats, and to hypothesize fire regime characteristics of parks and wilderness areas in the mountain west.  Among their findings were thresholds for climate moisture deficit which seemed to make fire frequency jump up and other areas which seemed to indicate fuel limitations may lead to lower fire severity.  So far, the approach has not been tried in Alaska, but might provide an interesting comparison to vegetation and future fire modeling being done by SNAP.


From Dobrowski and Parks, 2016, Fig. 1: Climate trajectories are defined by a source pixel (start) with a given temperature under current conditions (1981–2010) and a destination pixel (end) with a similar temperature under future conditions (2071–2100). Curved path (2) minimizes traversing pixels with large differences in temperature.

Citation: Parks, S.A.; Miller, C.; Abatzoglou, J.T.; Holsinger, L.M.; Parisien, M-A.; Dobrowski, S.Z. How will climate change affect wildland fire severity in the western US? Environ. Res. Lett. 201611, 035002.

Adam Young consults the crystal ball on future fire regime across Alaska

A paper just published by the indefatigable Adam Young, a PhD candidate at the University of Idaho, and colleagues pulls together a lot of information about climate, forest, tundra and fire to offer a glimpse of potential future fire regimes in different parts of Alaska.  By looking at fire occurrence at a multi-decadal time scale, the researchers drill down into how fire rotations are likely to respond to climate projections at a regional scale.

Young Fig 6 exerpt

Exerpt from Fig. 6, Young et al. 2016. Figures in the paper not only show the observed fire rotation for 19 subregions of Alaska (Figure A2 in supplement) with 60 years of fire occurrence data, but also project future rotations under various climate scenarios (in this case a mean of of 5 global climate models).

The use of advanced statistical models to build fire-landscape response models for boreal forest and tundra reaffirms prior findings of the sensitivity of fire regime to summer temperatures and moisture deficit. However, the effect is not uniform among regions: they identify a threshold at about 56⁰ F (30-yr mean temperature of the warmest month) and another threshold for annual precipitation where fire occurrence really seems to jump.  This latter finding accounts for results which project large increases in 30-year probability of burning for areas where these thresholds will be crossed in the next several decades.  For example, models project the Brooks Range foothills of the North Slope, Noatak tundra and the Y-K Delta may see increases in fire 4-20x greater than historical levels.  Some tundra areas are likely to experience fire frequency increase to levels not observed in the paleo record, spanning the past 6,000-35,000 years.  Across most of the boreal forest, fire rotation periods are projected to be less than 100 years by end of the 21st century.  This is useful information for natural resources management as well as fire protection agencies—a concise, well-researched, well-illustrated paper—put it on your summer reading list.

Young, A. M., Higuera, P. E., Duffy, P. A. and Hu, F. S. (2016), Climatic thresholds shape northern high-latitude fire regimes and imply vulnerability to future climate change. Ecography 39: 1-12.

Fire and Carbon Stores: the Rest of the Story

Estimates of carbon released from combustion of vegetation and organic soil during wildfires have improved dramatically over the past decade.  Biomass inventory, fire effects and fire severity studies have contributed more accurate data to improve these models. (See Ottmar 2007, Brendan Rogers webinar 2015)  However, figuring out the net effect of all the various effects of fire, the recovery phase and warming climate on the carbon stored in Alaska’s forests and tundra is a lot more challenging!  You’d have to consider changes in burn extent and/or severity, increases in plant productivity in recovering burns, changes in species composition and what that means for productivity, changes in permafCaptureIEMrost distribution and soil C decomposition, methane emissions and carbon fluxes in lake systems and wetlands–etc.!  A team lead by Dr. Dave McGuire at UAF has taken on this modeling challenge by applying their Integrated Ecosystem Model (IEM) which includes modules for fire, permafrost, and carbon cycling. Dave recently presented an overview of their findings at an IARPC-WCT/AFSC joint webinar (presentation slides available HERE).  In a nutshell, they found: 1) tundra holds 2x the carbon that boreal forest does in the same area 2) there has been a net C loss from boreal land area of about 8 Tg/yr over the last 60 years, primarily driven by large fires during the 2000’s 3) arctic tundra and SE Alaska still act as C sinks, compensating for these losses so that overall, Alaska sequesters about 3.7 Tg/yr,  4) increases in fire extent predicted with with warming climate will release even more C, but longer growing seasons and increased plant growth (as much as 8-19% increased productivity throughoCaptureALFut the remainder of this century) with warmer climate and higher CO2 concentration in the atmosphere are estimated to offset these losses under most of the climate projection scenarios. Since this nutshell summary glosses over a lot, you should take a look at the slides and the SNAP projects page with information on scenarios and the individual models used.

Where fire management and carbon studies connect . . .

Screen capture of the WFEIS calculator (

On the surface Alaska fire management and boreal ecosystem carbon studies have little in common.  But a deeper look reveals the connections between them.  Carbon scientists in the last decade have become increasingly interested in fire effects on the legacy carbon locked up in permafrost and the deep, slow-to-decompose organic layer of boreal forest floor (Kasischke et al. 2013, Genet et al. 2013).  Projections indicating more extensive, frequent and/or severe fires in northern latitudes with a rapidly warming climate, longer fire seasons, and more lightning (Romps, et al. 2014) lend a certain urgency to attempts to quantify the potential impacts of fire-released carbon on greenhouse warming.  Fire management agencies are less interested in long-term impacts of fire-released gasses but they are more and more driven to assess impacts of smoke on communities.  Work at the boundary between the two sets of interests has started to yield some interesting results.  For example, Michigan Tech Research Institute has joined their consumption field data from NASA studies to the USFS Consume Model and FCCS fuels maps and LANDFIRE fire perimeters in a web-based tool that provides users a simple interface for computing wildland fire emissions (1-km spatial resolution). The Wildland Fire Emissions Information System (WFEIS) can calculate tons of CO2 or other gases from large fires across the US and Canada from 1984-2010.  Although this tool is  for post-facto emissions analysis it is a good example of how large spatial data sets and complex equations can be united in a simple graphical interface allowing one to–say–query the forest fire emissions from the 231,000 acres burned in Alaska in 2010 (10.9 million tons CO2, 95,000 tons PM 2.5).  The hope is that weather modeling and research linkages with the common fire danger and risk rating system used in northern latitudes (CFFDRS) will soon bring this kind of application into the real-time and forecast prediction realm.

Does climate warming mean more lightning in Alaska?


Fig. 1. Yearly and monthly number of lightning flashes in Alaska from 1986-2010 (Farukh and Hayasaka, 2012)

A recent article in Science magazine (Romps, et al. 2014) postulated a 12% increase in lightning strikes over the continental US for each degree C of warming.  If this model holds true for Alaska, we should have already seen an increase in lightning strikes of roughly 20% in interior Alaska over the last 25 years since summer temperature has warmed by about 2.5 F–up to 3.7 F north of the Brooks Range (data from UAF Geophysical Institute).  So, has anyone looked at the trends in Alaska’s Automatic Lightning Detection Data to see what has been observed?  AFS has been collecting this data (publicly available at since 1986. It turns out the answer is yes!  Drs.Farukh and Hayasaka (2012) published an article on how large lightning storms characterized some of our largest recent fire seasons including this figure.  I’d like to challenge other  investigators to look at the regional significance of this phenomenon in the state, which could be an important fire regime driver in boreal forest/tundra, with the data which is now complete (ALDS went offline in 2013, replaced by a time-of-arrival system)!

Climate Change and Fire May Impact Northern Alaska Caribou Herds

Boundary Fire near the Canadian border 2005 (Photo: Tony Chapman, BLM Alaska Fire Service)

Will climate-driven changes in fire regime affect the Porcupine Caribou Herd? Caribou actively seek out and rely on high-energy lichen-rich habitats in the winter, and these lichen stands–also known as “caribou moss”– are uniquely sensitive to fire, requiring 60-100 years to recover after burning. Alaska climate modelers and biologists teamed up to study predicted annual acreage burned in the ranges of two northern herds: the Central Arctic Herd and the Porcupine Caribou Herd (of Arctic National Wildlife Refuge fame). Using newly developed models of wildfire response to climate changes, Gustine et al. (2014) modeled burn acreage in the next few decades under two possible climate trajectories: let’s call them “warm” or “hot”. Under the “warm” scenario they found little change through 2090 in the total old-growth habitats available to caribou of either herd. However, the “hot” climate scenario indicated fires grew larger, increasing average area of winter habitat that burned per decade. In brief, the Central Arctic Herd lost 11% of their winter habitat and the Porcupine Herd lost 21% through 2090 under the “hot” scenario. In addition, 30% of the Porcupine Herd’s current spruce forest habitat changed to a younger forest type or tundra. While biologists continue to debate how much habitat is required to sustain herds at present levels, habitat loss is rarely beneficial and availability of old-growth lichen stands is a big driver of caribou use patterns in most Alaska herds. If we humans have the power to rein in the pace of climate change to the “warm” scenario by slowing our greenhouse gas emissions, the caribou would probably appreciate it. This short illustrated paper is open access—read the whole research article at:

Citation: Gustine, D.D., Brinkman, T., Lindgren, M., Schmidt, J.I., Rupp, T.S., and Adams, L.G., 2014, Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic: PLOS One, v. 9, no. 7 100588, doi:10.1371/journal.pone.0100588

Research Brief: Fire Severity Filters Regeneration Traits to Shape Community Assembly in Alaska’s Boreal Forest

 Fire Severity Filters Regeneration Traits RB-2014-1thumbto Shape Community Assembly in Alaska’s Boreal Forest:  A recent paper by Hollingsworth et al. (2013) proposes that fire severity and a plant’s intrinsic regeneration strategy are key determinants in post-fire community recovery.  The authors identify species that may fare better or worse with predicted changes in Alaska’s fire regime. Hollingsworth–who is based at the University of Alaska-Fairbanks–bases her findings on a large (n = 87) and geographically diverse set of post-fire plots in interior Alaska boreal forest.   Read More >>  |  Download Research Brief PDF (850 kb)