Climate Change Keeps Expanding Canada’s Unprecedented Epidemic Of Forest-Destroying Beetles


Since the late 1990s, climate change has driven a massive expansion of forest-destroying Mountain Pine Beetles in Canada, delivering the country one of the worst ecological disasters in its history. The insects are not technically invasive, and until recently they existed in a natural balance with their environment; killing off older trees and making room for new growth. But as a new documentary chronicles, climate change eliminated many of the natural limits on the beetles’ geographic spread and their rate of reproduction.

The Mountain Pine Beetles were historically contained to the pine forests west of the Canadian Rockies, which had adapted to the insects’ presence. Their ability to spread and reproduce is heavily effected by temperature: as the climate warmed, cyclical cold snaps killed off less and less of the population. They dispersed over greater geographic areas and into higher elevations as warmer temperatures rendered those areas more hospitable. They even began reproducing twice per year rather than once. As a result, midway through the 2000s, the beetles crossed the mountains:

Farmers on the eastern slope of the Rockies described huge clouds of insects. They could hear them pinging off their steel roofs. The swarms were so dense they gummed up the windshield wipers on the farmers’ vehicles.

It was an unprecedented eastward spread of the beetles into the boreal forests of north-central Alberta, as well as further north into the Yukon and other areas. These forests had historically been untouched by beetle infestations and thus hadn’t adapted many natural defenses, leaving them unusually vulnerable. Meanwhile, over the span of a decade, the beetles ate through 18 million hectares of the western Lodgepole Pine forests in which they originated:


The orange shading is the beetles' spread from 2002-2006, while the red is 2007-2011. The solid red line is the spread's leading edge in 2011.

The damage now extends throughout the rest of North America as well. The beetles have wiped out 70,000 square miles of the Rocky Mountain forests in just over a decade — an area equivalent to that of Washington State — bringing the threat of increased wildfires thanks to the forests of dead trees left behind. In Wyoming, specifically, milder winters since 1994 have reduced the beetles’ die-off rate in the cold season from 80 percent per year to less than 10 percent. All told, the number of beetles attacking in a given year has increased as much as 60 times over, resulting in the largest epidemic ever recorded.

Making matters worse, the beetles are also producing a positive feedback loop that worsens climate change. As forests are killed off, it means fewer trees are left to draw carbon dioxide out of the atmosphere. At the same time, the dead trees themselves release the carbon they had previously stored — 990 million tons of CO2 from the forests of British Columbia alone, as of the middle of last year. As for the boreal forests the beetles are moving into, estimates put the amount of carbon stored there at 703 billion tons — twice the storage capacity per unit of area as tropical forests.

The good news, if you can call it that, is that the beetles have been so successful at killing off the lodgepole pines that they may have undercut their own food supply, putting an upper limit on their increase. The eastern boreal forests are also less contiguous, making it harder for the insects to continue marching eastward. And some suppression efforts — such as burning infected trees and removing threatened threatened stands to cut off the beetles’ pathway — have shown results.

On the other hand, the beetles born in less adapted forests are healthier and larger according to scientists, some of whom worry the insects could make it all the way to the Atlantic Coast.

18 Responses to Climate Change Keeps Expanding Canada’s Unprecedented Epidemic Of Forest-Destroying Beetles

  1. Ed Leaver says:

    Mountain Pine Beetle


    Natural controls of mountain pine beetle include woodpeckers and insects such as clerid beetles that feed on adults and larvae under the bark. However, during outbreaks these natural controls often fail to prevent additional attacks.

    Extreme cold temperatures also can reduce MPB populations. For winter mortality to be a significant factor, a severe freeze is necessary while the insect is in its most vulnerable stage; i.e., in the fall before the larvae have metabolized glycerols, or in late spring when the insect is molting into the pupal stage. For freezing temperatures to affect a large number of larvae during the middle of winter, temperatures of at least 30 degrees below zero (Fahrenheit) must be sustained for at least five days.

    When I was a kid growing up in Denver I recall at least two cold snaps of -20F in town that lasted three days. In the mountains to the west it would have been colder longer. Any more, yeah — its still Colorado and it’ll still occasionally get cold. But not that cold.

  2. Good article, except for the gratuitous insertion of logging propaganda:

    “… bringing the threat of increased wildfires thanks to the forests of dead trees left behind.”

    There is no evidence that a standing dead forest is a greater fire risk than a green forest; in drought conditions, the green forest represents the greater risk of uncontrollable wildfire.

  3. Ed Leaver says:

    One man’s “logging propaganda” is another’s sound forest management. The moment we waged war on natural forest fire, a century and a half ago, was the moment we assumed responsibility for the outcome. Yes, irresponsible clear-cutting gave the industry a deserved bad name. No excuses. But I’ve seen forests thinned by fire, by beetles, and by responsible logging practice. And I know which one I prefer.

  4. Paul Klinkman says:

    You seem to be making the case that some evidence has in fact been gathered on the subject, and the evidence is nuanced. The worst fire conditions are just after a once-green forest experiences short-term drought or some other condition that forces dieback.

    The main thrust of Climate Progress is inhibiting and reversing catastrophic climate change, but we’re also in part worried about climate change adaptation so that another Colorado Springs doesn’t burn down soon. Would creating more fire lanes or setting more judiciously controlled burns help adapt short-term to the situation?

  5. No. Such suggestions reflect the same mindset that advocates for additional rip-rap on barrier islands, or higher levees in floodplains. This mindset is part of the problem, not part of the solution.

  6. Along the lines of logging propaganda – anyone else follow the House Natural Resources committee hearing yesterday? – I’m uncomfortable with the headline here.

    I understand the desire to trumpet the dangerous impacts of climate change, which do include large ecological shifts and devastating changes.

    But the fact is that beetles rarely if ever “destroy a forest”. They can kill many of the trees in a forest and leave the look of devastation.

    Trees at different life stages are impacted differently, and in most if not all beetle flare-ups, many trees survive.

    Plus, the standing dead trees retain substantial biomass (including carbon) that the living forest will recycle and continue storing over time. And standing dead trees, in a couple of years of so, become less of a wildfire substrate than living forest!

    Industrial clearcut logging continues today on vast scales in Oregon and in western Canada. It is itself a significant climate change accelerator, with an emissions footprint comparable to large coal power plants. And the rallying cry of industrial timber in the US today, fully on display at yesterday’s Republican-dominated hearing, is that we need to accelerate logging (aka “active management”) to “protect” forests from fire and beetles.

    So dispelling timber mythology is itself an important part of the fight against climate change. Let’s try not to accidentally perpetuate it.

    More myths of industrial timber:
    The Corruption of Wood

  7. Joe Romm says:

    Not sure I agree with this.

  8. Joe, I appreciate your degree of uncertainty! :-) This seems like a fairly measured discussion of several chunks of the issue, even though it’s not at the peer-reviewed publication level:

    Mountain Pine Beetles Expansion in the West

    “When beetle outbreaks follow normal patterns and occur within the bounds of historical variation, they do not destroy, but rather support a forest’s long-term structure, function and resilience.

    “Yet, this time, something is different. For the first time, pronouncements that beetles destroy may have real meaning for some affected forests.”


    Keep in mind that a forest can undergo a transition in dominant species over time, and still be a forest. Most natural forests have some degree of species diversity that contributes to their long term bulk resiliency.

    On the other hand, some forests subjected to different environmental conditions by climate change may not recover from severe disturbance. In such cases, I would say the forest was “destroyed” by climate change – the combination of multiple climate change factors – as much as or more than by a specific disturbance cause, like beetles.

    Overall, please beware. It is simply true that much of the information that comes out from behind the “timber curtain” is highly biased, overgeneralized, and heavily exploited to further the political/economic grip of an industry that is effectively mining the deep legacy of our remaining temperate native forests.

    It’s much like the fossil fuel industry, in terms of generating outsized profits from simple extraction.

    But where fossil fuel extraction doesn’t functionally impoverish its underground substrates (as far as we know), simply killing the biosphere with emissions impacts afterwards, ongoing liquidation of the native forests gets us on both ends.

    The extraction of native forest through industrial clearcutting impoverishes whole watersheds, even entire regional landscapes, killing off priceless salmon runs, cutting water for agriculture, slashing biodiversity, and breaking rural communities. And it generates substantial net emissions, over critical timeframes, in addition.

  9. Mulga Mumblebrain says:

    Logging, as you say, is strip-mining the forests. How much of the forest that you possessed in 1492 remains today? In Australia the logging industry is remorseless. Every living tree is a pile of money waiting to be plundered, even if only for a pittance paid for woodchips. The idea of a forest as a complex system, a climax community of rich biodioversity does not just ‘not compute’ with the greedheads. It also affronts them as an insult to their hubristic belief in human dominance of and superiority to the mere ‘natural’ world. The destroyers pillage not just to reap money, but to assert their ego-driven dominance.

  10. Brian R Smith says:

    Lewis Cleverdon’s comments from last August
    are worth recalling to this thread


    In part:

    “Yet the resource need not and definitely should not be left to rot or burn. What it should be is the pump-priming resource for America’s program of carbon recovery, specifically the recovery over time of its ‘historic emissions’, with the forests’ full replanting being funded by the sale of products.

    “Simple mobile charcoal retorts could convert about 70% of the wood’s carbon to charcoal, with about 28% of the wood’s energy potential being released as crude woodgas which is readily converted to methanol by small modular stills.

    “This would not only provide an unprecedented scale of rural employment, but also sufficient charcoal for biochar production to treat around 160 million acres at 10Ts/acre, thereby both raising soil fertility and also moisture moderation. In addition it would launch a potentially highly sustainable methanol silvifuel industry (as distinct from agri-fuels) on a very substantial scale. Both of these technologies are of major international significance and replicability, and the US would do very well to set the lead on them.

    “So where are the green entrepreneurs seeking major innovative necessary enterprises,
    and the progressive politicians seeking mass employment options and the raising of US international respect,
    and the farm lobby seeking improved drought and flood resistance of the farmlands,
    and the manufacturers seeking new equipment mass-production options for home sales and export,
    and the conservationists seeking the restoration of the forests and the avoidance of this massive feedback loop on global warming?”

    So there is economic potential in the necessity of dealing with sequestration and restoration in vast tracts of damaged forest – which should be included in calculations of ultimate C02(e) release. But also this: 70,000 sq. mi. of contiguous dead forest represents an enormous hit to fragile boreal ecosystems, species, watershed physiology & hydrology. More reason to get in there on the ground quickly (with some economic incentive) and begin restoration/carbon recovery/employment. It doesn’t have to go to Big Timber schemes.

  11. Lewis Cleverdon says:

    Brian – thanks for reposting my comment from last year – perhaps the ‘isolationist’ school of environmentalism will attempt to respond this time rather than just ignoring the threat issues it raised and the benign potentials of their remediation.

    The threats are now looking pretty dire. The beetle has crossed the Rockies and has made the species jump into the Boreal Forest’s jack pine. The raised potential for wildfire is plainly not immediate but rather it rises once the trees begin to fall, generating a massive fuel load on the ground, as was shown in some of last year’s exceptional fires of old beetle-hit lodgepole pine in Washington State.

    The failure to recognize the facts that such fires can destroy the seed bank, and that exposed soils will both erode and be more prone to drought, and that together with increasing weather volatility including drought these all diminish the chance of natural regeneration, may explain some of the isolationist’s attitude. They fail to appreciate the fact that without respectful integration of human aims with the forests’ wellbeing we’re looking at the beginning of the forests’ eradication. AKA Dieback.

    As one notable part of the GHG cocktail of forest fire emissions, NOx outputs are greatly raised by high temperature fires. NOx has a GWP of 289 over 20 yrs, and a residence time of about 300 years, and is also a primary ozone precursor and acid rain precursor, meaning that this is a significant and exceptionally long-lasting threat, particularly to forests.

    Also, in a generally fine article Jeff Spross misses one critical factor, namely that of the CH4 output from the anaerobic decay of dead trunks which greatly multiplies the total CO2e output from a killed forest. Taking CH4’s GWP on the crucial 20yr time horizon and the figures of 3.664 and 1.25 as the multiples of carbon’s weight for CO2 and CH4 respectively, the rise in CO2e from 6%,12%, and 18% of carbon being emitted as methane is about 3-fold, 5-fold and 7-fold respectively (299%, 497% and 696%).

    As Jeff remarks, there are about 700GtC held in the Boreal Forest, of which much is now at risk from the bark beetle. If just 10% of that is killed in the next 20 years, we’re looking at ruinous CO2e emissions – Even at 6% of carbon output as CH4, if spread over a 20 yr outgassing period it would average about 38.3Gt CO2e per year – which is substantially more than current Global anthro-CO2 emissions, let alone those of North America.

    Several conclusions can be drawn from this.
    – First, it is clear that neither a societal collapse nor a successful Emissions Control treaty (with a timelagged end of anthro warming in 2080) will halt the acceleration of this forest-dieback feedback loop, which is of a potential scale, by itself, to replace uncontrolled BAU anthro-CO2 emissions and their warming impact.

    The stringently supervised RD&D of both the Carbon Recovery and Albedo Restoration forms of Geo-E is thus obviously needed for their inclusion as essential additional components of a ‘tripod’ global climate treaty. Those who oppose this inevitable requirement simply aren’t up to speed on the scientific reporting of the compounding threats we now face.

    – Second, those who oppose the responsible processing of the beetle-killed gigatonnes of deadwood for biochar and co-product methanol are not only encouraging their massive unnatural GHG emissions, thus worsening AGW and hastening the dieback of the forests they aim to protect, they are also directly hindering what is probably the best opportunity on the planet for the unilateral launch of the essential Carbon Recovery program and its technologies and best practices research.

    – Third, in doing so they also reinforce the anti-enterprise anti-employment anti-integration profiles of environmentalism that have been critically disempowering for decades – to the point that a Democrat president can blithely ignore ecological concerns in favour of pursuing the adopted Neo-Con global climate policy of studied inaction.

    I’d suggest that it is high time US environmentalism shifted its basic philosophy from the isolationism of evidently failed preservationist strategies to the integrationism of advancing society’s respectful engagement with the ecosphere, and particularly its forests, on grounds that we are, inescapably, a crucial part of the ecology.

    The effective response to the harvesting and replanting of the beetle killed forests is a unique opportunity in which to express this change of approach, and if done well it could be seminally productive in breaking the entrapment of organized ecological concerns within one of the two tribes of the political circus that afflicts America’s prospects.



  12. “The raised potential for wildfire is plainly not immediate but rather it rises once the trees begin to fall, generating a massive fuel load on the ground, as was shown in some of last year’s exceptional fires of old beetle-hit lodgepole pine in Washington State.”

    As long as you keep basing your arguments on anecdotal misattributions of beetle-fire relationships, you will convince no one knowledgeable of the ecological, and carbon sequestration, values of natural forests.

  13. sokorny says:

    Mulga, have you ever worked in the Australian forest management sector? I am a forester and I can tell you with 100% certainity your views are wrong. Forestry in Australia is about sustainable management, sure there are cases where they fail (but from my experience this isn’t due to “greed” but due to inept managers).

    I would suggest the biggest issue with me regarding forestry in Australia is the “greens” push for an end to native forestry. This has led to plantations taking being prefered to native forests when land is reclaimed (the USA similarly has more forest area now than prior to 1400s, yet their area of native forests continue to decline) … and the environmental movement has largely led to this shift.

  14. sokorny says:

    That was what your whole previous argument was based on Brian though? Not to mention this comment too.

    Dead trees create a more hazardous landscape to fight fires in, as they pose a threat to fire fighters. Many dead trees were will be indiscriminatley felled before a fire to minimise the risks (common safety practice in Australian bush fires).

    The only positive of dead trees in a forest is that spotting may be decreased (that is as there are no leaves, bark may have fallen off etc.), therefore less ability for embers to “jump” contaminant lines.

  15. Lewis Cleverdon says:

    In my view knowledgeable peole are already well aware of “the ecological, and carbon sequestration, values of natural forests” so your statement is incoherent.

    Your appeal to academia to support your advocacy of inaction is equally vain, as your claim that beetle-fire relationships are merely “anecdotal misattributions” simply betrays your ignorance of the peer-reviewed literature. Try for instance
    Simard, Martin, William H. Romme, Jacob M. Griffin, and Monica G. Turner. 2011. “Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests?” Ecological Monographs 81:3–24″ in which the probability of crown fires is shown to decline at the expense of raised fuel loading on the ground. Speaking of the fuel load once grey stage dead forest starts to fall, they remark:
    “In subsequent decades, coarse wood loads doubled and canopy base height declined to 0m”. And as any profeesional firefighter or forester will inform you, doubling the natural fuel load on the ground will raise the probability, and the intensity, of wildfire, with the latter effect maximizing the damage to the seed bank.

    However, your focus on denying the beetle-fire relationship is of course a diversionary canard – depending on the deadwood’s age and moisture content, from the critical CO2e perspective wildfire may be greatly preferable to leaving the wood to rot and maximize its CH4 output, just as the deadwood’s harvesting and processing for sequestration is hugely preferable to seeing the wood burn.

    The inaction that you advocate maximizes the probability that much of the forest killed by the bark beetle will be permanently lost, since natural regeneration under an increasingly volatile climate strongly favours colonizers such as switchgrass and other competitors.

    In addition, your advocacy of inaction carries a complicity in the probability of massive ongoing forest loss generating CO2e outputs exceeding the present global CO2 emissions – i.e. far larger than those for which even the Koch brothers are culpable.

    If you want to be taken seriously as a forest conservationist you’d do well to start supporting the necessary mitigation actions for their conservation, rather than clinging to out-dated inneffective isolationist strategies of forests’ exclusion from benign intervention.

  16. >>>> ““In subsequent decades, …”

    You do not even understand what you cite. I pointed this about before about your silly anecdotal assertion about beetle-killed deadfall being “responsible” recent Washington fires.

    Asserting an inevitable association with 50 years time interval (the time it takes for the canopy to reappear) is handwaving.

  17. >>>> “The only positive of dead trees in a forest …”

    Typical myopia of a tree farmer, who sees only a fiber farm, not a diverse ecosystem.

  18. Lewis Cleverdon says:

    Your lack of any argument refuting the massive CO2e output the beetle-killed forests represent informs me that you have none, but would rather cling to your diversionary denial of the raised probability and intensity of wildfire due to the timber’s collapse into fuel load on the ground.

    Your claim that it takes 50 years for the canopy to reappear is obviously false. See “Conifer Regeneration after Forest Fire in the Klamath-Siskiyous: How Much, How Soon?” by Shatford, Hibbs & Puettmann in the Journal of Forestry, whose very painstaking researches show a regeneration period to a highly combustible canopy of just 9 to 19 years.

    Thus where regeneration after beetle kill is possible under the increasingly volatile climate and the raised competition from pioneer species, the canopy closes over a doubled fuel load on the ground, providing prime conditions for wildfire. I would repeat the point that those areas of beetle killed forest which fail to burn will provide far more damaging CO2e outputs due to their methane content.

    Your fixation with the isolation of beetle killed forest from responsible forestry intervention and your lack of interest in discussing the proper approaches to avoiding the beetle’s massive feedback on climate destabilization means that it appears a waste of time conversing with you.