The Threat of Wildfires and Climate Change in Canada

In 2023, Canada experienced a record-breaking wildfire season because of climate change. 14.9 million hectares of land burned, an area slightly larger than Greece [1]. This number represents over seven times the average area of land burned in Canada annually from 1986 to 2022. These wildfires directly impacted communities by destroying property and infrastructure. They released smoke into the air, negatively impacting human health. Evacuations, firefighting efforts, health costs due to poor air quality, damage to infrastructure, and damage to natural forest resources imposed billions of dollars in economic costs [2].

With this context in mind, our publication "Global climate change below 2 °C avoids large end century increases in burned area in Canada" uses new mathematical modeling methods developed at Environment and Climate Change Canada to explore how climate change will impact future wildfires in Canada. Our findings reinforce the need for urgent action to prevent global temperature rise due to climate change from exceeding a 2 °C global threshold.

_{A bar chart showing the total burned area in Canada by year, highlighting the extreme 2023 wildfire season [1].}

How does climate change increase wildfire activity?

Wildfire requires an ignition source to start, and abundant dry fuel like wood and leaves to spread. Climate change makes these fuels drier, allowing wildfires to spread faster. Rising temperatures and changing precipitation patterns, the direct results of climate change, lead to longer and hotter fire seasons (spring through fall in Canada). Vegetation dries becoming more flammable during long periods of hot dry weather, increasing the risk of larger and more frequent wildfires. Moreover, climate change may lead to more frequent and intense lightning storms. This, in turn, could cause more frequent and widespread lightning ignition since most large wildfires in Canada are ignited by lightning.

Our new wildfire model is built for high-latitude (boreal) forests and represents these key causes of wildfires in Canada. It is based on the Canadian Forest Fire Weather Index System and the Canadian Forest Fire Behavior Prediction System. These systems have been used in Canada, and around the world, for decades to quantify the potential for wildfires to occur and spread. The Canadian Forest Fire Weather Index System is most commonly used to decide when to ban campfires and other burns to manage wildfire risk. We adapted this system for use in a broader mathematical model called the Canadian Land Surface Scheme Including Biogeochemical Cycles.

_{A wildfire danger rating sign, like those seen in Canada’s national and provincial parks. Source: dronepicr, CC BY 2.0, via Wikimedia Commons.}

Why 2° C?

Our cutting-edge wildfire model simulates the impact of climate change on wildfires across several future scenarios, also referred to as Shared Socioeconomic Pathways. The future is unknown, however, these scenarios have been developed by international organizations based on the input of interdisciplinary researchers including economists, climate change researchers, and social scientists. These scenarios reflect how future emissions may evolve depending on the path humanity takes [3].

The first group of scenarios represents high emissions rapid climate change scenarios (Shared Socioeconomic Pathways 370 and 585). They assume continued reliance on fossil fuels and limited international efforts to control climate change. The result of these scenarios is increasing emissions and significant levels of global climate change. These contrast with the low emissions climate change scenario (Shared Socioeconomic Pathway 126). This scenario assumes that the international community takes aggressive action to prevent climate change. The result of such action would be sustainable growth, and limiting the global temperature rise due to climate change to below 2°C.

Our results: two dramatically different paths

Our study points to two dramatically different futures for wildfire activity, depending upon the trajectory of climate change.

For the high emissions rapid climate change scenarios, wildfire activity will dramatically increase between now and the 2090s, as compared to the 2010s. The average annual burned area in the 2090s in Canada is expected to be around 10.9 million hectares. In other words, in an average wildfire season in the 2090s, 350% more land will burn than in an average wildfire season in the 2010s. This means that an average wildfire year in the 2090s would be close to what Canada experienced in the extreme 2023 wildfire season. Emissions of CO₂ and other gases associated with wildfires would increase by around 250% compared to the 2010s.

In stark contrast, for the low emissions controlled climate change scenario, wildfire activity in the 2090s is about the same level as in the 2010s, around 3.3 million hectares per year. In other words, the negative impacts of wildfire on property, health, human well-being, and the economy remain at their current levels, on average.

_{Satellite imagery of the West Kiskatinaw River Wildfire in British Columbia Canada on June 7, 2023. Source: Copernicus Sentinel data 2023, CC BY 2.0, via Wikimedia Commons.}

Future work and the path forward

Our scientific understanding of wildfire, and our ability to mathematically model it will continue to advance. These advances will produce better estimates of how climate change will impact lightning and dry fuels. These research efforts can play an important role in informing how Canadians adapt to and mitigate future climate change.

Nonetheless, the overall message of our work is clear. Keeping global temperature rise due to climate change below 2 °C will help Canada maintain wildfire at current levels. This outcome requires immediate reductions in greenhouse gas emissions. Wildfires in Canada are not just a domestic issue. The impacts of wildfires in Canada in 2023 stretched into the United States and as far as Europe. In previous years, other northern countries have experienced record wildfire seasons including Sweden in 2018 and Russia in 2021. Keeping global temperature rise due to climate change below 2° C is the most direct pathway to avoid these and other negative impacts of climate change on ecosystems, economic growth, and human health.

References:

1.  Jain, P. et al. Drivers and Impacts of the Record-Breaking 2023 Wildfire Season in Canada. Nature Communications 15.1 (2024): 6764. https://doi.org/10.1038/s41467-024-51154-7
2. MacCarthy, J. et al. Extreme wildfires in Canada and their contribution to global loss in tree cover and carbon emissions in 2023. Global Change Biology 30.6 (2024): e17392. https://doi.org/10.1111/gcb.17392
3.  Riahi, K. et al. The Shared Socioeconomic Pathways and their energy, land use, and greenhouse gas emissions implications: an overview. Global Environmental Change 42 (2017): 153–168. https://doi.org/10.1016/j.gloenvcha.2016.05.009