Climate change expected to sharply increase Western wildfire burn area — as much as 175% by the 2050s

A major new study, “Impacts of climate change from 2000 to 2050 on wildfire activity and carbonaceous aerosol concentrations in the western United States” finds a staggering increase in “wildfire activity and carbonaceous aerosol concentrations in the western United States” by mid-century under a moderate warming scenario:

We show that increases in temperature cause annual mean area burned in the western United States to increase by 54% by the 2050s relative to the present-day … with the forests of the Pacific Northwest and Rocky Mountains experiencing the greatest increases of 78% and 175% respectively. Increased area burned results in near doubling of wildfire carbonaceous aerosol emissions by mid-century.

This graph shows the percentage increase in area burned by wildfires, from the present-day to the 2050s, as calculated by the model of Spracklen et al. [2009] for the May-October fire season. The model follows a scenario of moderately increasing emissions of greenhouse gas emissions and leads to average global warming of 1.6 degrees Celsius (3 degrees Fahrenheit) by 2050. Warmer temperatures can dry out underbrush, leading to more serious conflagrations in the future climate.”

And this is just the mid-century prediction for the IPCC’s “moderate” A1B scenario (CO2 at 522 ppm in 2050), which predicts “mean July temperatures to increase by 1.8°C from 2000 to 2050.”  This is not the worst-case emissions path, which we are currently on (see U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm “¦ the worst-case IPCC scenario trajectories (or even worse) are being realised” “” 1000 ppm).  What would happen by 2100 on our current emissions path, when the mean July temperature increase from 2000 is triple (or more) the 1.8°C that the researchers modeled?  Turns out someone did model that a few years ago.

Back in 2004, researchers at the U.S. Forest Services Pacific Wildland Fire Lab looked at past fires in the West to create a statistical model of how future climate change may affect wildfires.  Their paper, “Climatic Change, Wildfire, and Conservation,” published in Conservation Biology, found that by century’s end, states like Montana, New Mexico, Washington, Utah, and Wyoming could see burn areas increase five times.

For completeness sake — and because I remain optimistic that someday the media will routinely make the connection between increased forest fires and global warming — let me note that back in 2006 Science magazine published a major article analyzing whether the recent soaring wildfire trend was due to a change in forest management practices or to climate change. The study, led by the Scripps Institute of Oceanography, concluded:

Robust statistical associations between wildfire and hydroclimate in western forests indicate that increased wildfire activity over recent decades reflects sub-regional responses to changes in climate. Historical wildfire observations exhibit an abrupt transition in the mid-1980s from a regime of infrequent large wildfires of short (average of 1 week) duration to one with much more frequent and longer burning (5 weeks) fires. This transition was marked by a shift toward unusually warm springs, longer summer dry seasons, drier vegetation (which provoked more and longer burning large wildfires), and longer fire seasons. Reduced winter precipitation and an early spring snowmelt played a role in this shift.

That 2006 study noted global warming (from human-caused emissions of greenhouse gases such as carbon dioxide) will further accelerate all of these trends during this century. Worse still, the increased wildfires will themselves release huge amounts of carbon dioxide, which will serve as a vicious circle, accelerating the very global warming that is helping to cause more wildfires.

For more on the new study, see here.

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21 Responses to Climate change expected to sharply increase Western wildfire burn area — as much as 175% by the 2050s

  1. Chris Winter says:

    Has this paper been published in final form? Your link shows me a draft copy, and I can’t find any version of the paper in the JGR for 2009, or any such paper searching Google Scholar for “Jennifer Logan.”

  2. 103 deg. F the official high in Seattle yesterday, 106 in Portland. Hit 105 briefly at the NOAA station in Seattle. Very dry heat, heat index the same as heat. Ideal to cook up forest fires. Meanwhile, Washington state coastal counties in some of the wettest places on Earth have countywide burn bans because of drying and observers report canopy dieback in Olympic Peninsula rainforests.

    Years ago, back in the 1980s, when I was part of the ancient forest movement in the Northwest, I spoke with a logger at a logging site idled by protest. He said to me, “Jesus is going to come back in 20 years and burn these trees all down. So why shouldn’t we cut them?” The logger may have been partly right about the trees burning down, but it ain’t Jesus Christ that’s torching them. I do fear that great, stand-replacing fires will be the prime picture of global warming in the Northwest, and when our big, biomass-heavy forests west of the Cascades start going, watch out.

  3. Gail says:

    Patrick Mazza, I would say that wildfires are going to happen all over the earth, wherever there are trees, because the ozone is poisoning them, which people are stupidly ignoring.

  4. Roger says:

    Thank you so much for your helpful research on ozone’s impact on trees, and the direct links between ozone and carbon dioxide!

    We’ve been wondering what the heck’s going on when we start to notice more and more sad, stressed, thin, dying white pines in the otherwise-beautiful woods of New Hampshire.

    It’s as if we’re experiencing death by a thousand cuts, but with no understanding of where the cuts are coming from, nor how they’ll play out. Too bad that most humans only learn from experience–and we’ve only got ‘one time through’ on this ride!

  5. Scatman says:

    I read that forrest fires are good because they allow new animals and plants to move into a mature ecosystem. They mix things up and get many more nutrients back into the soil. This according to complex system theories.

  6. Gail says:

    Scatman, that is true or rather, it used to be true.

    Forests now are drier than they were before the industrial revolution unleashed greenhouse gasses. They are also warmer. Not only does this kill trees, making for more fuel for wildfires to be bigger, hotter and move faster, in the western US and Canada a warmer climate has allowed the pine bark beetle to run rampant. It does not get cold enough in the winter to keep the population in check. Vast swaths of dead trees are tinder and that is not part of the ecosystem of the past to which you refer.

  7. Bernie says:

    Do you have a citation to support your claim that there is an increase in temperature at high altitudes where Mountain Pine Beetle’s are currently decimating trees?
    The data I am familiar with (see for example ) indicates that the current infestation is due to other factors. Please note that the absence of extreme cold says nothing about monthly or annual temperature trends. Moreover these MPB infestations have occurred in the past, so I am not sure what you mean when you say it is not part of the ecosystem.

  8. Chris Winter says:


    Almost every related source I find online mentions the recent absence of long periods of cold (-30° to -40°F) winter temperatures in the regions affected. The New York Times has a story on the beetle infestation:

    If you want a primary source, here’s one sponsored by several western-state forest agencies:
    Recent Forest Insect Outbreaks and Fire Risk in Colorado Forests:
    A Brief Synthesis of Relevant Research
    W.H. Romme1, J. Clement, J. Hicke, D. Kulakowski, L.H. MacDonald, T.L. Schoennagel, and T.T. Veblen

    It’s a 36-page PDF which says on page 6:

    “A warming climate during the last 100 years, particularly in the last few decades, also appears to have played a role in driving recent insect outbreaks. Higher temperatures and a longer frostfree period subject the trees to additional water stress, and may accelerate the growth and development of the beetle larvae. The warming trend of the past few decades (Westerling et al. 2006) may have contributed to the current outbreak of mountain pine beetle in Colorado, as well as recent outbreaks that have occurred outside of Colorado in historically marginal environments for bark beetles, such as at the northern extent of their range in Canada (Carroll et al. 2004) or in high elevations of the northern Rockies (Logan and Powell 2001, Hicke et al. 2006). Furthermore, changing climate conditions are thought to have been responsible for a very severe mortality event in the piñon trees of southern Colorado and adjacent states. Between 2002 and 2004, extensive piñon mortality occurred during a severe drought and an accompanying outbreak of Ips bark beetle (Breshears et al. 2005). Although a more intense drought actually occurred in the 1950s, piñon mortality was far more severe and widespread in 2002 – 2004, apparently because the unusually warm conditions that accompanied the recent drought put additional stress on the trees and allowed more extensive outbreaks of the piñon Ips beetle. Breshears et al. (2005) documented elevated maximum and minimum temperatures at numerous weather stations throughout the Four Corners region during the past decade.”

  9. Deep Sixer says:

    Uh.. your 2006 major study? It only looked at fires since the 1970s. Fire suppression began in the early 1900s. Most of the country used to burn every 5-10 years. Your major study should have looked at 1900, 1800, 1700, even 700. Try doing a search for “fire regime” or something relevant to the field.

  10. Gail says:

    Roger, the implications of ozone effects on vegetation are staggering and it’s time for that to become a major portion of the discussion of CO2 impacts on climate change.

    The fact that high levels of ozone damages plants is well documented, but we need much more research on the topic – and widespread education.

    Aside from the terrible loss of fruits and nuts, (and birds and every other species that relies on trees and shrubs) and the amplifying effect on on warming when CO2 sinks become emitters, trees and other plants make the oxygen we breathe.

    Just the past couple of weeks I am starting to see the same chlorophyl loss in the leaves of some annuals as well. It’s very frightening considering how quickly it is happening and how insanely oblivious just about everyone is.

  11. Bernie says:

    Many thanks for the Romme et al summary. It appears to be a very careful and circumspect piece of work.

    A couple of their responses caught my eye. First almost at the outset they note “There is no evidence to support the idea that current levels of bark beetle or defoliator activity are unnaturally high. Similar
    outbreaks have occurred in the past.” This generally coincides with the point that I raised.

    Secondly, while they note that “Breshears et al. (2005) documented
    elevated maximum and minimum temperatures at numerous weather stations throughout the Four Corners region during the past decade.”, a look at the actual article (, particularly Figure 1 panels C and D, does not support a long term increasing trend in temperature of any significance for the forested areas of the South-Western States.

    The synthesis also references Westerling et al (2006). If you look at the Wyoming data that I referenced above, you will see that it in part supports Westerling et al’s comments on an early spring (i.e., March) increase in temperature. However, the same Wyoming data shows a decline in July and declines at the end of the fire season October and November. Obviously this is only the data for Wyoming. Unfortunately the Westerling et al article – including the supplementary information, do not provide an easily accessible source for their temperature data. Their cut-off for the start of their analysis in 1970 is a bit unfortunate since, as the Breshears et al article clearly shows, 1970 was the bottom of a cool cycle.

    My point here is that MPB and wildfires are real issues. It is short-sighted and ultimately counter-productive to keep attributing such unwanted events to “global warming” as opposed to pinpointing more precise and proximate causes.

  12. Gail says:

    I love the “global warming.” Is that anything like the theories of “plate tectonics” or “evolution” or “gravity”?

  13. Bernie says:

    You said: “Forests now are drier than they were before the industrial revolution unleashed greenhouse gasses. They are also warmer. Not only does this kill trees, making for more fuel for wildfires to be bigger, hotter and move faster, in the western US and Canada a warmer climate has allowed the pine bark beetle to run rampant.” Do you have a better way of summarizing this syndrome?

  14. Gail says:

    Bernie, Sure! Happy to oblige…

    how’s this…

    We’re Screwed.

  15. Bernie says:

    I am not sure that “screwed” is the kind of construct that helps explain anything.

  16. Gail says:

    does “Completely f!cked” resonate any better?

  17. There’s always denial.

    Retreating to delusional thinking is so much more comfortable. Until…

  18. Steve Bloom says:

    Chris, it’s common for publicity on papers to go out a few days prior to formal publication. AGU blocks search engine access to “in press” papers, which is why you couldn’t find it. Expect it to turn up sometime this week.

    Bernie, your propensity for selective citation and convenient misinterpretation reminds me of none other than RP Jr. You can report back to him that you got a poor reception here.

    Oh, but you want examples. OK — citing temp data that cuts off in 2000 as evidence that the *current* MPB outbreak isn’t temp-related is stupid or dishonest (your choice). Also, I must say your assertion that a reduction in cold extremes has no effect on temperature trends is novel. Possibly there’s a universe out there somewhere with different physical laws than this one, where such a thing might be true, but I’m afraid it’s not this universe.

  19. Bernie says:

    I haven’t selectively cited or misinterpreted anything. Locating relevant data series is not easy. I asked for citations and gave the one that I had found. Do you have more current temperature data for high altitude locations in the Western States? I am perfectly open to additional data. I certainly never said that the MPB outbreak is not impacted by extreme temperatures. My point about the absence of extreme temperatures (-40C)that kill the dormant MPB and overall temperature trends is absolutely accurate.

  20. Bernie says:

    Here is a site with more current Wyoming data – – but you will need to scrape the data before making state-wide generalizations. As you will see if you click on some of the graphs the temperature record shows no obvious trend.

    Perhaps some of the analysts associated with Climate Progress can find a better source or can compile the data themselves.

  21. SBVOR says:

    1) Has anybody noticed that the cited “study” has been submitted for peer review but has not yet passed peer review? Heck, I can’t even read the draft report. I get a font error when opening it.

    2) There is reasonable evidence of a correlation between temperature cycles and MPB infestation cycles. The specific geography is irrelevant. Expand the scope to North America and…

    A) Here we have the climate-alarmist-in-chief admitting that:

    “1934 is the warmest year in the contiguous states”

    B) Here we have evidence that the MPB infestation of the 1930’s was more widespread than the current infestation. Click here for the relevant excerpt.

    C) Here we have evidence to suggest that, just in the last 10,000 years of the Holocene, the planet has been through quite a few periods considerably warmer than the last decade. Thus, if MPB infestations are correlated with warmer periods, it stands to reason that there have been many, many MPB infestation cycles just in the last 10,000 years.

    3) Like all things in nature, MPB infestations are cyclical events. The only thing unusual about this one is that the Forest Service has created an unprecedented banquet for the MPB. Click here for the facts on that.