So what do we know about the effect of climate change on wildfires? We know that climate change is already contributing to an increase in the number and intensity of wildfires, and that this will continue to get worse as global temperatures rise. However, climate change also brings a lot of variability and instability to weather patterns, so as the climate changes we might experience some years with high wildfire occurrences and some years with low wildfire occurrences.
In general, climate change results in warmer temperatures and a lengthening of the summer season. This has several interconnected effects:
1. Warmer summers are more likely to dry out the boreal forest.
2. Longer summers and shorter winters will enable forest pests (like the mountain pine beetle and emerald ash borer) to expand their ranges and populations, thereby killing more trees, which results in more flammable material.
3. Longer summers will result in a longer fire season.
4. Warmer and drier conditions will allow fires to burn more deeply into organic material (like peat and duff), which could result in “holdover fires”, which are fires that will continue to smolder through damp periods (even over the winter in some cases), exploding into wildfires as weather conditions change.
5. Research has suggested that lightning strikes are increasing with climate change, and will continue to increase, thus resulting in more wildfires. This is significant because most of the area burnt by wildfires in the boreal result from fires ignited by lightning. This is because lightning-ignited fires often occur in areas less accessible to wildfire suppression teams and resources.
Canadian fire researchers estimate that given the current pace of climate change, and assuming there is no significant reductions in carbon emissions slowing the rate of warming, by 2050 the area burned in Central and Western Manitoba (i.e. the Boreal Plains) and Eastern Manitoba and Northwestern Ontario (i.e. the Boreal Shield West) will see a 40% increase in annual area burned by wildfires. The Taiga of Northern Manitoba will see a 78% increase in area burned. To keep pace with these fires, Natural Resources Canada estimates fire protection costs will double in the next 20-25 years.
Complicating all of this is the impact of wildfire on climate change. Wildfires emit a significant amount of CO2 and black carbon when they burn, and it is estimated that more CO2 is emitted by the dead wood left behind decomposes in the years after a fire. While wildfire contribute to CO2 emissions (ie.climate change), there is also the possibility that some of the particulates released into the atmosphere by fires can reflect heat from the sun, which can contribute to short-term cooling, similar to the effects of volcanic eruptions. Also, fires spur on new forest growth, which can offset carbon emissions. In general, Canada’s forests have been a carbon sink, but wildfires have the potential to make them a carbon source, particularly if climate change limits the regrowth potential of the forests. That said, wildfires are part of the natural carbon cycle, and the overall carbon emissions from wildfires is minute compared to fossil fuel emissions[MOU1] .
The one thing that is uncomplicated is our response to climate change and wildfire, which requires quick and effective action.
First, we need to reduce human-caused sources of carbon (i.e. fossil fuel emissions) to slow the speed of climate change to reduce the risk and potential of future wildfires.
Second, we need to adapt our communities to the changing climate and the wildfire regime it has already produced. Adaptation is of particular importance to frontline communities; those communities that already exist in the wildland urban interface that are most likely to bear the brunt of wildfires.
The recently released federal budget includes funding for wildfire preparedness on First Nations and this is a step in the right direction. However, more action is needed to adapt our communities, infrastructure, and social systems to the potential risks posed by a new climate change driven fire regime.