Forest Fires and Climate Change

Forest fire

Doug Findlater, mayor of West Kelowna, recalls seeing the 2003 Okanagan Mountain Park fire sweep into town: “It kind of looked like a war movie, with houses blowing up all over the place,” he says. More recently, Canadians watched with horror as the immense Fort McMurray fire of 2016 threatened the city. The Fort Mac fire caused the evacuation of almost 90,000 people and quickly became the most expensive natural disaster in Canadian history, destroying 2400 buildings and causing about $10 billion in damage. [1]

Forest fires make headlines across Canada every summer. They regularly devastate millions of acres of forest [2] and sometimes threaten entire communities with sudden, catastrophic violence. Destructive fires have an enduring impact on the community that lingers long after people return home to resume their lives. Findlater speaks from experience when he says “life is never quite the same again after you’ve been evacuated.” The extraordinary danger and lasting impacts of wildfire explain why we spend so much money – about a billion dollars a year – fighting it. [3]

Fire is a seasonal summer threat because it can only start, intensify, and spread in hot, dry weather. Findlater reflects that “as a mayor, I don’t really look forward to summer in the way most people do.” He notes that as climate change brings on longer, drier summers, Canadians will have to live with more and more risk of more and more serious wildfires, and that we have to take decisive steps to manage the growing danger.

Climate Change and Fire Weather

When forest fire researcher Mike Flannigan looks ahead at what climate change means for wildfires in Canada, he doesn’t beat around the bush: “in a word, the future is smoky.”

Flannigan has been studying fire for over thirty years. He’s researched the key ingredients of destructive wildfires – fuel, ignition, and weather – all over the world. His work, and the work of hundreds of other researchers, shows that climate change is predicted to worsen all three ingredients across most of Canada, making global warming a triple threat to our forests.

Read More: Fire's important natural role

Wildfire is a natural part of the boreal forest life cycle. Fires help clear litter from the forest floor, recycle nutrients back into the soil, open up gaps in tree stands to promote new growth, and kill invasive species and forest pests. The heat from forest fires is even needed by some trees, such as the Jack Pine, for reproduction. When fire meets human civilization, however, it becomes a dangerous or catastrophic threat.

When he considers what’s in store for Canada, Flannigan says simply that “There is a lot more fire in the future, and we better get used to it.” More and more Canadians are living, working, and playing in Canada’s forests. That means more people are likely to be affected by larger and larger fires – even catastrophic ones. “Was Fort McMurray a one-off?” Flannigan muses: “Heavens, no.”

To figure out what climate change means for forest fires in Canada, Flannigan and a team of researchers at the Canadian Forest Service analyzed the findings of almost 50 international studies on climate change and fire risk. [4] They found that our future looks “smoky” because climate change will worsen the three major factors that influence wildfire: having dry fuel to burn, frequent lightning strikes that start fires, and dry, windy weather that fans the flames.

Another recent study [5] by Flannigan and several other scientists predicts that western Canada will see a 50% increase in the number of dry, windy days that let fires start and spread, whereas eastern Canada will see an even more dramatic 200% to 300% increase in this kind of “fire weather.” Other studies predict that fires could burn twice as much average area per year in Canada by the end of the century as has burned in the recent past. [6]

Read more: Wildfire Fuel

Warm weather can dry out the landscape very quickly. The drier grasses, brush, and trees get, the more likely they are to both catch fire and to stay burning. Global warming has a direct and obvious effect on this risk by raising temperatures, which will dry out vegetation more quickly and more thoroughly. The presence of all this dry fuel will allow more fires to start and then burn farther and wider.

It takes only a few hot days to create fire conditions, even when there have been recent downpours and even flooding. For example, in British Columbia, the 2017 fire season smashed wildfire records for the largest total area burnt, and this record was smashed again only one year later in 2018. [7] This catastrophic summer of fire immediately followed a spring of rainstorms and floods. These seemingly contradictory dangers overlapped, leading the Okanagan emergency operations centre to warn residents not to be complacent about fire risks because of the flooding. [8]

Climate change is predicted to cause large increases in the number of very hot days across the country (see our map of +30°C days). This means our forests are likely to become much more flammable from coast to coast to coast.

Climate change can also promote forest fires in less direct ways. [9] In BC and Alberta, warming temperatures are enabling the dramatic spread of the mountain pine beetle, which has affected more than 180,000 square kilometres of forest (an area larger than all of Greece). [10] These beetles kill their host trees, and have created vast swaths of standing deadwood which are now huge reservoirs of wildfire fuel. The pine beetle is only one of many damaging forest pests that are likely to spread thanks to warmer winters caused by climate change. [11]

See our “Forest Pests and Climate Change” article for more on insect risks.

Read more: Lightning

All the dry grass and wood in the world won’t become a wildfire if nothing sets it ablaze. As Mike Flannigan points out, “Forest fires are caused by two things: lightning and people.”

Unfortunately, rising temperatures promote the development of more storms capable of producing lightning, the chief cause of forest fires in remote areas, and more than half of wildfires overall. [12] Scientists working from climate models conservatively predict an 80% increase in the number of lightning strikes in Canada by the end of the century. [6]

Canada has averaged over 7000 forest fires per year since 1990. [13] More than half are caused by lightning, so a near-doubling of lightning strikes could push us to almost 9,000 fires per year by the end of the century.

Read more: Fire weather

The third element that determines the severity of wildfire is dry, windy weather: conditions that Mike Flannigan calls “fire weather”. Dry heat helps create more fuel to burn, and wind both spreads wildfire more rapidly and makes it much harder to put out.

Climate change is stacking the deck so that hot, dry and windy weather shows up more frequently than it used to. Surprisingly, one reason for this increase is the rising temperature of the Arctic.

Although the Arctic is very far away, its climate has dramatic effects on the weather of southern Canada. The far north of Canada is warming much faster than the south, and as the Arctic warms up, the jet stream slows down and meanders. [14] This means that weather that would normally pass by in a day or two tends to stay put for much longer, causing flooding (if rainstorms persist for days or weeks) and drought (when hot, dry weather just doesn’t let up).

So, global warming creates higher temperatures that make more dry fuel available to burn and also results in more persistent hot and dry fire weather that lets fires intensify and spread.

Warmer weather is also causing earlier snow melt and later fall frosts, which are expanding the fire season, or the range of time when the weather is warm enough and dry enough for fires to occur. All across the country, fire season is starting earlier and lasting longer. Flannigan notes that the Alberta fire season begins a full month earlier than it used to, at the beginning of March rather than April.

See our map of projected changes in the Frost-Free Season across Canada to see how the fire season might expand.

Mitigation

There’s a vicious cycle connecting forest fires and climate change: warmer temperatures make fires more likely, and burning forests release greenhouse gas pollution that makes global warming worse. [15]

This means that overall efforts to reduce greenhouse gas emissions and slow global warming will also help prevent forest fires. And on the other hand, working to reduce the number and severity of forest fires will also help slow climate change.

Many aspects of wildfire are out of our control, but as Flannigan notes: “every human-caused fire is preventable.” And Findlater reports that many of the recent fires near Kelowna have been caused by human carelessness. A world of ever-increasing fire risks and consequences will demand more fire bans and forest closures as well as more innovative and life-long fire education to reduce the number of human-caused fires.

Adaptation

How do we “get used to” a world with much more wildfire?

Fortunately, there are a number of things individuals and municipalities can do to reduce fire risk. Fire Smart [https://www.firesmartcanada.ca] guidelines are available for individuals and for community leaders. Municipalities can create and maintain fire buffers around and within their communities by bulldozing trees, removing built-up forest litter, and making creative use of parks and open spaces as fire breaks. Findlater would like to see provincial regulation of fuel-rich private land, requiring better management that will reduce fire risk to the community as a whole. And individual homeowners and businesses can design buildings with fire safety in mind, for example avoiding the use of flammable materials in construction and landscaping.

Fire is inevitable, and climate change will make it more common and more dangerous: it only makes sense to plan how we build, work, and live near forests with fire safety in mind.

We also need to adapt our wildfire response strategies to a world of more frequent, more intense fires. Natural Resources Canada estimates the fire protection costs could double in Canada by 2040 as we attempt to keep up with the worsening risk. [3] Flannigan argues that remote fires should be allowed to run their course by burning freely without human interference. Concentrating fire-fighting budgets and capacity on wildfires that directly threaten human lives and livelihoods will prevent the most catastrophic impacts, naturally reduce the buildup of dry fuel in the wilderness, and prevent firefighting costs from growing wildly out of control along with our worsening forest fires.

Many effective and innovative firefighting strategies are already in place. Findlater suggests that excellent systems have been created to share emergency-response leadership and resources across regions, provinces, and the entire country. He notes that British Columbia’s regional emergency management services are getting better and better at coordinating their wildfire response: but “sad to say,” it’s because “we’ve had a lot of practice.”

References

  1. Natural Resources Canada "Forest Fires
  2. Alam, Rafat et al. “Rapid Impact Assessment of Fort McMurray Wildfire.” MacEwan University / Institute for Catastrophic Loss Reduction.
  3. Natural Resources Canada Cost of Fire Protection.
  4. Flannigan, M. D., Krawchuk, M. A., De Groot, W. J., Wotton, B. M., & Gowman, L. M. (2009). “Implications of changing climate for global wildland fire.” International Journal of Wildland Fire. https://doi.org/10.1071/WF08187
  5. Wang, X., Parisien, M.-A., Taylor, S. W., Candau, J.-N., Stralberg, D., Marshall, G. A., … Flannigan, M. D. (2017). “Projected changes in daily fire spread across Canada over the next century.” Environmental Research Letters, 12(2), 025005.https://doi.org/10.1088/1748-9326/aa5835
  6. Mike Flannigan. “Fire and Climate Change”
  7. CBC. “2018 now worst fire season on record as B.C. extends state of emergency”
  8. Regional District of Okanagan-Similkameen"From Floods to Fire: Be Fire Smart!"
  9. Natural Resources Canada “Forests: Climate Change Impacts”
  10. Natural Resources Canada “Mountain Pine Beetle Fact Sheet”
  11. Ramsfield, T. D., Bentz, B. J., Faccoli, M., Jactel, H., & Brockerhoff, E. G. (2016). “Forest health in a changing world: Effects of globalization and climate change on forest insect and pathogen impacts.” Forestry, 89(3), 245–252. https://doi.org/10.1093/forestry/cpw018
  12. Natural Resources Canada "Indicator: Forest Fires"
  13. Canadian Council of Forest Ministers. Canadian Wildland Fire Strategy: A 10-year Review and Renewed Call to Action.
  14. Mann, M. E., Rahmstorf, S., Kornhuber, K., Steinman, B. A., Miller, S. K., & Coumou, D. (2017). Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events. Scientific Reports, 7, 45242. https://doi.org/10.1038/srep45242
  15. Stocks, Brian J. and Ward, P.C. Climate Change, Carbon Sequestration, and Forest Fire Protection in the Canadian Boreal Zone Sustainability in a Changing Climate: An Overview of MNR's Climate Change Strategy (2011-2014). Ontario Ministry of Natural Resources. Climate Change Research Report CCRR-20. 2011.http://www.climateontario.ca/MNR_Publications/stdprod_088316.pdf

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