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Wildfire – Just One More Gift from Climate Change.


The Fort McMurray fire

The Canadian news this past week has been filled with harrowing tales of the plight of people caught up in the Fort McMurray wildfire, and reports have spilled over into the international press.  It began the afternoon of Sunday May 1st when two blazes erupted southwest of Fort McMurray, a city of 80,000+ people, in the heart of Alberta’s tar sands country.  One fire was brought under control, but the other worsened and an initial voluntary evacuation order was issued for one suburb, Gregoire, on Sunday afternoon.  Firefighters continued to battle the fire and the voluntary evacuation order remained in place through Monday, primarily because of air quality concerns.  By late Monday the fire had consumed over 1000 ha of bush.  Conditions worsened on Tuesday with continued hot, dry weather and high winds.  What had been a voluntary order became a mandatory evacuation order extended to several suburbs.  By Tuesday evening the order was extended to the entire city.

Wildfire_near_Highway_63_in_south_Fort_McMurray_May42016_leadimagesize DarrenRD

People fleeing Fort McMurray on 4th May via Highway 63, as flames fill the sky.
Photo © DarrenRD CC-BY-SA-4.0

Some people, leaving on Monday and Tuesday had headed north towards motels and accommodation facilities associated with various mining corporations.  These people had to move again, going south of the city this time, as did people who had gone to the first evacuation center set up just south of the city.  The fire kept changing direction as the winds swirled around.

On Wednesday May 4th the Province declared a state of emergency and the fire continued to grow.  Mandatory evacuations were extended to several locations surrounding Fort McMurray. About 10,000ha of land had now been burned, and at least 1600 homes had been destroyed.  The fire was burning so hot that trees were exploding into flame and the fire was generating its own winds and lightning.  The fire continued to grow, and had consumed 85,000 ha by May 5th, 100,000 ha by May 6th and 156,000 ha by May 7th.  As of May 9th, it had expanded to 204,000 ha, and was moving north-east towards the Saskatchewan border, away from the city and most of the oil infrastructure.  Some 2,400 homes have been destroyed but over 80% of the city and all critical infrastructure has been saved.  Nevertheless, the situation remains dangerous, and it will be some days or weeks before people are able to return home.

Wildfires continue burning in and around Fort McMurray, Alta., Wednesday, May 4, 2016. (Jeff McIntosh/CP)

Fort McMurray is invisible in this photo of the fire taken on 4th May.  Image © Jeff McIntosh/CP

One atypical consequence of the Fort McMurray fire has been its effect on the global oil supply.  Because of the extreme fire risk, and because many of their staff were busy trying to save, and then to flee from their homes, tar sands operators shut down pipelines and suspended production and upgrading operations.  About 1 million barrels per day of oil production is on hold until the worst of the danger passes.  Fortunately, from an economic perspective, the relative soft global oil market has weathered this disruption relatively easily, but Canada’s GDP growth expectations have been further scaled back by economists.  The irony of the ‘climate-change leads to severe wildfire in the heart of the tar-sands’ has not gone unnoticed in Canada, but fortunately most of us have had the decency to focus for now on the plight of the thousands of displaced people.

To give a sense of the size of this fire, Maclean’s has published a series of maps showing the burned area superimposed on several cities elsewhere in North America.  It is a big one.

Vancouver & New York vs FM fire

Area burned by the Fort McMurray fire at May 4th (dotted black line), May 5th (red line), and May 7th (pink area) superimposed on maps of Vancouver and New York.  Images © Maclean’s.

Wildfire on the rise

Nor was this the only wildfire in Canada last week.  Across Canada, until last week there had been 1,156 fires reported this year which together damaged 53,000 ha.  Of these 149 were currently active, 15 out of control.  The number of fires to date is almost twice the average, and the area burned is ten times the normal rate over the past decade.  Currently, there are 5 significant fires burning in British Columbia, 29 in Alberta, 17 in Saskatchewan, and two on the Manitoba-Ontario border.  While most are human caused, the exceptionally warm and dry weather that western North America has been experiencing this year is what has set the stage for an exceptional year.  That hot, dry weather is a result of el Niño and climate change.

The link between wildfire and climate change is not one that permits us to say ‘this fire was caused by climate change’.  Climate change alters fire risk, making the likelihood of fires greater.  Individual fires are still caused by appropriate weather and forest condition, and by lightning or human carelessness to provide the ignition, but with climate change these conditions occur more often.

One of the many consequences of climate change is a heightening of wildfire risk in many regions.  With warmer weather comes increased evaporation leading to dryer soils and plant material.  Early in the spring, prior to leafing out, forests can become particularly dry if there is no rain, and that is what has happened in western Canada.  Even in central Ontario, where fire risk is generally low relative to more northerly locations because of the generally more mesic conditions, Natural Resources Canada estimates a significant increase in fire risk by mid-century.  In a 2013 paper in Ecological Applications, Yan Boulanger of the Laurentian Forestry Centre, Canadian Forest Service, and five colleagues, provided estimates showing that in the central Ontario region where I live (Muskoka and points north), the fire incidence, measured as number of wildfires per 100,000 ha per year was likely to increase from 0.01, the average over 1961 to 1990, to 0.06 by mid-century, while the annual area burned would grow to 0.19% per year from its average from 1961 to 1990 of 0.03%.  These increases are both about 6-fold, a substantial increase in fire risk even if it remains relatively low compared to that at points north or west.

Nor is 2016 the first year that increased wildfire occurrence has been seen.  The fires in Saskatchewan in 2015 were similarly memorable, and other countries have witnessed similar increases.  The current rate of deforestation in south-east Asian countries is high because climate change increases risk of fires getting out of control.  And Australia was experiencing extreme fire conditions several years ago during hot summers.  The record fires in Victoria in 2009, at that time the worst in Australian history, claimed 163 lives and caused more than $4 billion in damage.  Serious fire hit Australia’s south-east again in 2013, and record fires hit South Australia in 2015.  While serious wildfire has long been an Australian given, the sense there is that fires are becoming hotter, bigger, and more destructive, and that climate change is to blame.

Apart from the damage, and risk to life, that wildfires can cause, fire liberates vast stores of carbon locked up in forests thus adding to our greenhouse gas problem.  Indeed, in Canada, the shift towards more frequent and more extensive fires could be a major impediment to achieving our tepid commitment on emissions reductions under the Paris Accord.  Those commitments are already proving a difficult task and an increase in wildfires makes their achievement even more difficult.  Canada’s emissions reduction plans, such as they are, have relied to a large extent on improved management of forested lands to contribute by using forests as effective sinks for carbon.  But as our fire risk rises, there is real danger that our forested land (remember, Canada holds the world’s largest extent of boreal forest in the world) will become a net source of CO2, meaning that we will have still more emissions to curtail to bring total emissions below 2005 levels.  Of course, I expect that Canadian politicians will turn themselves into pretzels maintaining that emissions due to wildfire should not be counted, but the fact remains that the emissions will be there and they will be warming the planet.

And then there is water

Climate change leads to many different changes in our environment.  In my immediate neighborhood, the pattern of precipitation is set to alter during the remainder of this century so that we will get about 10% more rain and/or snow by mid-century, but with a shift in seasonality of precipitation to favor the winter and spring.  As a consequence, as reported in a recent report from the local Muskoka Watershed Council, our winters are set to become much wetter, while our summers and falls are going to be dryer.  (The drying results, not from reduced rainfall during those months – the rainfall in summer and fall is not expected to change much at all – but by increased evaporation and transpiration due to the warmer weather.)  As a consequence, the pattern by which water flows through our ecosystem – the hydrology – is set to become substantially different to today.  This changed hydrology is likely to lead to greater risk of severe flooding in late winter and spring, and a much reduced flow during summer and fall.  The more seasonal flow will impact local, small-scale hydroelectric power generation; the health of our wetlands, streams, and rivers; and the maintenance of lake levels on our recreational lakes.  I find the fact that many seasonal residents are currently demanding that ‘the government’ do a better job of maintaining lake levels, and preventing spring floods, somewhat amusing – no level of government is mandated to keep lake levels constant here, and even if one were, that task will likely become impossible within a few decades.  When flow is strongly seasonal, you cannot keep water levels constant.  (Those readers who live near tidal water may find the whole idea of a constant water level peculiar – I agree with you.)

Submerged-Dock Rosskokadotcom

The ‘culture’ in my part of the world increasingly assumes that water levels in lakes remain constant, even during the spring thaw.  They do not, as this submerged dock reveals, and with climate change making water flow markedly more seasonal in this region, seasonal fluctuations will become more extreme than at present.  Photo ©

In many parts of the world, the effects of climate change on hydrological systems are becoming profound.  Present day migrations from North Africa and the Middle East, while usually reported in terms of societal disruption and strife, are more fundamentally caused by the progressive drying of that large part of the world, a drying that will continue as climate warms.  It was crop failures that triggered the movement of rural people to the cities of Syria as failed farmers looked for work to buy food for their families.  The increased pressures in crowded cities led to tension, to relatively ham-fisted crack-downs by authoritarian governments, to civil war, to IS, and to mass migration as people look desperately for a place they can eke out some sort of existence.  As climate changes, such causal sequences will repeat in other places.

The progressive drying of the American south-west would also lead to mass migration were it not for the fact that mostly Americans can afford the infrastructure to pump water from deep underground, or pipe it vast distances from places where it is more plentiful to places where it is not.  But North America is over-using its aquifers, and these vast stores of water, accumulated through millions of years, are being diminished, while surface supplies are being stretched far more than they should be.  There are many things California should be doing with respect to water, including far tighter regulation of the amount used in agriculture, or to wash cars or keep lawns unnaturally green, but mostly, at present the approach still seems to be to improve the delivery systems rather than to reduce demand.  An ironic example of the complexity of this issue: Saudi Arabia is leasing land in California to grow forage for livestock back home – compared to the Middle East, California has lots of water.  As climate changes there will be ever more stories of water shortage and water conflict in the US south-west, and the amount of water available to use will inexorably decline.  Given that California agriculture contributes 13% of US agricultural products, and 14% of US agricultural exports, climate change could have substantial impacts on food prices and food availability in many places, simply because it is likely to further reduce water availability in California.

So, fire and water; that only leaves earth and air, and climate change affects air directly, not least by warming it and enhancing the likelihood of more violent storm events.  So what about earth?  One of the first ways in which rising sea level has impacts on the land is through salt water intrusion into groundwater.  We often hear that small Pacific island nations are at danger of sinking forever beneath the sea due to climate-caused sea level rise.  The image of an entire small nation disappearing beneath the sea in an Atlantis reenactment captures the imagination, but this is only the final step in the onslaught by a changing climate.  Salt water intrusion can make fragile island aquifers unsuitable for agricultural or human use long before the island nation disappears beneath the waves.  Reduced rainfall (especially on low islands which typically have low rainfall) can impede groundwater recharge sufficiently that human use rapidly exhausts the resource.


Funafuti atoll, the capital of Tuvalu, has an average elevation of 2 meters.  Low-lying islands like this are most at risk of saline intrusion into aquifers as sea level rises.  Photo ©

In 2014, a Geoscience Australia science team undertook a climate change vulnerability assessment for the islands of the Pacific.  For both low rainfall and sea level rise impacts on groundwater, they showed that low islands characteristic of atolls had the highest vulnerability, and for many islands of this type, throughout the Pacific, that vulnerability was very high.  Climate change will create severe water stress on such islands long before sea level rises sufficiently to permanently erase them.  That does not make the situation for small island nations any easier; it makes it a whole lot more difficult.  While some mitigation is possible with careful management of use of aquifers, small, low-lying islands will lose their aquifers eventually – this is a climate-induced problem for which there are no real solutions.

Let’s remember also that low-lying, coastal plains, supporting some of the most fertile productive land around the world, while less poetic than tiny tropical islands, will also suffer salt water intrusion as climate changes and sea level rises.  These lands will lose their fertility to the detriment of millions of humans dependent on the agricultural products grown.

I started talking about forest fire.  I’ve ended with images of tiny islands running out of fresh water.  Climate change is real.  It is happening now.  It will get worse if we do not rein in our emissions of greenhouse gases.  Its effects on our environment and our lives come in many different forms – physical, biological, sociological, economic.  And some of those effects are problems for us that have no solutions.  The challenges of adapting effectively to a changing climate are profound, and not always solvable.  Better to do our level best to halt climate change in its tracks.