Temperature Trends in Canada: Historical Data vs. Future Projections

1. Recent Studies on Temperature Trends in Canada

Today, climate change affects all parts of the world, and Canada is no exception. Past studies also showed that Canada, especially indigenous communities, will face an increase in temperature and its consequences in the future. As predicted in the Six Nations of the Grand River, the temperature in the period from 2006 to 2099 under both RCP 4.5 and 8.5 to increase between 3 and 6 degrees Celsius, which will lead to frequent and intense heat waves with an estimated increase of 0.4 to 1.5 days per year (Deen et al., 2021). The temperature challenges caused by climate change are also significant in large Canadian cities, including Ontario. The results of the studies show that the annual average temperature and heat waves will increase significantly under the IPCC SRES A2 and B2 scenarios in Ontario, in which southern Ontario, especially the Toronto-Windsor corridor, will experience the highest temperatures and the most intense heat waves. Northern Ontario is also expected to experience cooler temperatures but is at risk of prolonged heat waves, underscoring the need for climate resilience measures (Li et al., 2017). The impact of climate change will not be limited to temperature rising, covering other aspects of human life in Canadian cities. Projections for future periods around 2040, 2060, and 2080 indicate that while cold-related mortality will remain the predominant cause of temperature-related deaths, rising temperatures may increase heat-related mortality in cities such as Hamilton, London, Montreal, and Regina (Martin et al., 2012).

2. Temperature Trend in Canada

Despite past studies regarding climate change and its impact on Canada's future temperature, these studies were limited to local or urban areas in Canada using old scenarios. Here we paint a more detailed picture of historical and future temperature trends in Canada (all of Canada, not local) under the most recent scenarios presented by the IPCC and CMIP6 climate projections.

2.1. Methodology

Here, the CMIP6 climate projections, specifically employing data from the GFDL-ESM4 model, are utilized to assess the temperature trends in Canada (John et al., 2018; CMIP6 climate projections - Copernicus). The GFDL-ESM4 model, part of the family of Earth System Models (ESMs) developed by the Geophysical Fluid Dynamics Laboratory (GFDL) in the USA, is used to simulate near-surface air temperature patterns. As a Global Climate Model (GCM) included in the CMIP6 project, GFDL-ESM4 provides comprehensive simulations of global climate processes, accounting for the interactions between the atmosphere, oceans, land surface, and ice (John et al., 2018). While downscaling techniques are often employed to spatially refine GCM projections for regional and local climate analysis, they are not used in this study. Previous studies have demonstrated that GFDL-ESM4 reproduces near-surface temperature patterns with good agreement even without downscaling. Downscaling remains useful for enhancing the spatial resolution of climate projections and improving the reliability of regional-scale analyses, especially for adaptation and mitigation efforts. However, given the satisfactory performance of GFDL-ESM4 at its native resolution for large-scale regions, downscaling is deemed unnecessary for the current study. Additionally, in cases where downscaling is applied, it is recommended to sub-select the GCMs that best capture the climate processes relevant to the study area to reduce computational costs and improve the accuracy of regional projections (Reboita et al., 2024; Nishant et al., 2022; Masud et al., 2021).

The CMIP6 framework provides a comprehensive dataset of daily and monthly global climate projections generated through a variety of experiments, models, and time periods. This dataset underpins the Intergovernmental Panel on Climate Change's (IPCC Assessment Reports) 6th Assessment Report. The focus is on near-surface air temperature, defined as the temperature of the air at 2 meters above the Earth’s surface, which is derived by interpolating between the lowest model level and the surface, accounting for atmospheric conditions. The historical experiments included in the CMIP6 dataset span the period from 1850 to 2014, serving as a reference for evaluating future climate scenarios. The climate projection experiments are used from the Shared Socioeconomic Pathways (SSP), covering the years 2015 to 2100 (CMIP6 climate projections—Copernicus).
To analyze temperature trends in Canada, changes are evaluated in periods including near-term (2021–2040), mid-term (2041–2060), and long-term (2081–2100) relative to both the recent past (1995–2014) and the pre-industrial period (1850–1900) (AR6 Physical Science Basis, 2021; AR6 Synthesis Report, 2023). To enhance our understanding of temperature trends in Canada, we analyze annual and seasonal temperature values.

2.2. Annual Temperature Trend in Canada

The results presented in Table 1, Table 2, Table 3, and Fig 4 are from the GFDL-ESM4 model. The CMIP6 dataset includes both historical data (1850–2014) and future projections under different Climate Change Scenarios from 2015 to 2100. The temperature data is based on near-surface air temperature, measured at approximately 2 meters above the Earth's surface to assess the impact of climate change on temperature trends in Canada.

The annual temperature trends indicate a marked increase in Canada’s temperatures over time. Table 1 reveals that the historical recent past period (1995–2014) shows significant warming compared to the pre-industrial era, with average temperatures rising from -3.42°C to -2.61°C. This increase is consistent with global trends driven by rising greenhouse gas concentrations, deforestation, and other anthropogenic factors that have contributed to a warming climate (AR6 Synthesis Report, 2023).

Table 1. Historical Temperature Trends in Canada vs Future Temperature Trends in Canada (Annual)

The future projections under the SSP scenarios demonstrate various levels of warming based on differing levels of greenhouse gas concentrations and socioeconomic development.

• SSP1-2.6: This scenario represents a pathway with a strong focus on sustainable practices and low emissions. It shows a moderated warming, with annual temperatures changing from -1.43°C in the near-term to -1.22°C in the mid-term and -0.94°C in the long-term. The limited warming trend reflects significant adaptation and mitigation efforts to reduce emissions and stabilize climate change impacts.

• SSP2-4.5: This pathway reflects moderate efforts to control emissions. The trend reveals an increase in temperatures from -1.46°C in the near term to a slightly positive value of 0.52°C in the long term. This indicates that, while mitigation efforts are in place, they are not sufficient to halt warming entirely, where the average near-surface temperature increases about 2°C in the long term compared to the near-term period.

• SSP3-7.0: This scenario represents high emissions with limited global cooperation on climate action and shows a significant increase in temperatures. From -1.71°C in the near term to 1.73°C in the long term, this scenario indicates a more pronounced warming effect as greenhouse gas concentrations continue to rise substantially, raising the temperature in Canada significantly.

• SSP5-8.5: This scenario projects the highest emissions with rapid economic development reliant on fossil fuels. The long-term warming reaches up to 2.76°C, indicating drastic temperature increases, which could lead to severe climate impacts if mitigation measures are not implemented. Compared to pre-industrial and recent pact periods, the SSP5-8.5 scenario suggests an increase in near-surface temperature in Canada with values of 6.18°C and 5.37°C respectively.

These projected increases in near-surface temperature indicate that without aggressive climate policies, the warming trend in Canada is expected to continue and potentially accelerate, with significant implications for ecosystems, human health, and socioeconomic systems. These scenarios highlight the necessity of Climate Change Adaptation and mitigation strategies to control the rising temperature in Canada. 

Table 2 presents Sen’s slope analysis, which quantifies the magnitude of temperature trends in Canada under different scenarios and time periods. The pre-industrial period (1850–1900) exhibits a minimal warming trend with a Sen’s slope of +0.008°C per year, while the recent past (1995–2014) shows a stronger warming trend of +0.045°C per year. This suggests that temperature increases accelerated during the recent past, likely due to anthropogenic influences.

Table 2. Historical Temperature Trends in Canada vs Future Temperature Trends in Canada (Sen’s slope)

According to future scenarios, SSP1-2.6 represents a future with stringent mitigation efforts. The near-term (2021–2040) sees a slight warming of +0.033°C per year, but cooling is projected during the mid-term (2041–2060) with a negative slope of -0.044°C per year, followed by minor warming again in the long-term (2081–2100) at +0.013°C per year. This reflects a potential stabilization of temperatures if global emissions are reduced. Under the SSP2-4 scenario, the warming trend continues across all future periods, with the near-term showing +0.050°C per year, the mid-term increasing further to +0.067°C per year, and the long-term reaching +0.034°C per year. This indicates that moderate emissions reductions may slow but not completely halt warming trends.

SSP3-7.0, which is a high-emission scenario, reveals relatively modest warming in the near-term (+0.008°C per year) but accelerates significantly in the mid-term (+0.125°C per year) and long-term (+0.071°C per year), highlighting increasing temperature trends as emissions grow. SSP5-8.5, the highest emission scenario, shows the most dramatic warming, with a steady increase in temperature trends from the near-term (+0.061°C per year) to the long-term (+0.092°C per year).

The results indicate a clear trend of increasing temperatures across Canada, with varying rates of change depending on the emission scenario. Lower-emission pathways (SSP1-2.6) show more moderate warming, with potential cooling in the mid-term. In contrast, higher-emission scenarios (SSP3-7.0 and SSP5-8.5) demonstrate significantly stronger and more persistent warming, especially in the midterm and long term.

2.3. Seasonal Temperature Trend in Canada

Seasonal temperature changes reveal distinct patterns across different periods and scenarios. Table 3 outlines historical seasonal temperatures from the pre-industrial period to the recent past, while Table 4 provides future projections of monthly temperature under varying SSP scenarios. Historically, both spring and winter have shown significant warming. Spring temperatures increased from -4.54°C to 2.65°C, and winter temperatures rose from -17.24°C to -15.22°C when comparing pre-industrial values to recent past data. In contrast, summer temperatures have remained relatively stable, with a slight decrease from 9.62°C to 9.21°C. Fall, however, has displayed a cooling trend, with temperatures decreasing from -1.54°C in the pre-industrial period to -7.30°C in the recent past.

Table 3. Seasonal Historical Temperature in Canada 

The future projections show significant variability across scenarios and seasons, as outlined below:

• In the spring, the warming trend continues across all SSP scenarios, with temperatures projected to increase substantially in Canada. For instance, SSP5-8.5 projects temperatures rising from -4.54°C in the pre-industrial and 2.65°C in the recent past periods to 4.24°C in the near-term and 11.64°C in the long-term. Rising spring temperatures in northern regions can have profound effects, as seen in northern Alaska, where snowmelt has advanced by approximately 8 days since the mid-1960s. This shift is linked to warmer spring conditions and decreased snowfall, which in turn affects the surface radiation budget and accelerates regional warming (Stone et al., 2002). Such changes not only alter local climates but also have broader ecological and socioeconomic consequences. Even under lower-emission scenarios like SSP1-2.6, the temperature increase remains significant, ranging from 4.49°C to 8.83°C, indicating that spring will continue to warm regardless of the mitigation measures taken.

• In summer, projections indicate overall warming, though with some differences across scenarios. Under SSP5-8.5, temperatures increase from 8.99°C in the near-term to 9.08°C in the long-term. Under SSP1-2.6, there is a moderate temperature decrease over time, suggesting that mitigation measures can have a notable impact on moderate summer temperatures.

• In fall, the trend shows cooling across all scenarios, though the magnitude of change varies. Under SSP5-8.5, fall temperatures shift from -6.12°C in the near-term to -5.50°C in the long term, while SSP1-2.6 predicts a greater decrease, from -6.89°C to -10.59°C in Canada. These changes may affect several aspects of human lives and ecosystems by causing shits in fall events. Shifts in fall events, such as leaf senescence, bird migration, and fruit ripening, can significantly impact ecosystems. These changes influence carbon dynamics, favor the spread of invasive species and pathogens, and alter predator-prey relationships. Vulnerable species are particularly at risk due to the reshuffling of ecological interactions (Gallinat et al., 2015).

• Winter temperatures exhibit the most significant warming across all scenarios. Under SSP5-8.5, the projected increase is dramatic, rising from -12.86°C in the near-term to -4.55°C in the long-term. This substantial warming will have far-reaching impacts on ice and snow cover, particularly in northern regions of Canada where permafrost and ice play a critical role in the environment. Rising winter temperatures in northwestern Canada are contributing to significant permafrost thaw, leading to boreal forest loss (Carpino et al., 2018). Even under lower-emission scenarios like SSP1-2.6, winter warming remains significant, with a rise from -13.24°C to -8.84°C, suggesting that regardless of mitigation measures, winter conditions in Canada will become milder.

Table 4. Seasonal Future Temperature Trends in Canada

The results show that in the near term, temperatures show moderate increases, particularly in spring and summer, while fall and winter temperatures remain notably negative. Moving into the mid-term, a pronounced rise in average temperatures is observed across all seasons, with spring and summer remaining relatively high. By the long-term period, further increases are evident, especially in spring, indicating a continued trend toward warmer conditions, although fall and winter temperatures are still negative, albeit with less severity compared to earlier periods. Overall, these trends highlight a concerning trajectory of warming, emphasizing the urgent need for climate action to address the impacts of rising temperatures on ecosystems and human populations. This situation underscores the critical importance of Climate Change Adaptation and developing strategies to mitigate and adapt to climate change effects in the future (Fawzy et al., 2020).

3. Conclusion

Due to the profound effects of climate change on human livelihoods and the environment, the historical and future temperature trends in Canada are assessed in this article. The CMIP6 climate projections, specifically data from the GFDL-ESM4 model, are utilized to assess temperature trends in Canada. This Earth System Model simulates near-surface air temperatures, accounting for interactions between the atmosphere, oceans, land surface, and ice. Projections cover historical (1850–2014) and future scenarios (2015–2100) under the SSP pathways. Temperature trends are analyzed for near-term (2021–2040), mid-term (2041–2060), and long-term (2081–2100) periods relative to both recent past and pre-industrial baselines. The focus is on annual and seasonal temperature changes. The analysis of historical and future temperature trends in Canada indicates a clear warming pattern that varies across different scenarios and seasons. Under all SSP pathways, there is an upward trend in temperatures, with the extent of warming largely dependent on future emission levels. The seasonal analysis reveals that spring and winter are particularly sensitive to warming, while fall shows a cooling trend. The projected changes have significant implications for ecosystems, agriculture, water resources, and socioeconomic systems. Mitigation and adaptation efforts will be critical in managing these changes and minimizing the adverse impacts of climate change on Canada’s environment and communities. The findings underscore the importance of global climate policies and regional planning to address the challenges posed by a warming climate.