Will changes in the North Atlantic and Barents Sea contribute to the severe 2023 fire season in Canada?

In the late spring to summer season of 2023, Canada witnessed unprecedented wildfires, with an extensive burning area and smoke spreading as far as the East Coast of the United States and Europe. Here, using multisource data analysis and climate model simulations, we show that an abnormally warm North Atlantic, as well as an abnormally low Barents Sea ice concentration (SIC), are likely key climate drivers of this Canadian fire season, contributing to ~80% of the fire weather anomaly over Canada from June to August 2023. Specifically, the warm North Atlantic forms an anomalous regional zonal cell with ascending air over the Atlantic and descending air encircling Canada, creating hot and dry local conditions. Meanwhile, reduced Barents SIC leads to a high-pressure center and reinforces the dry northern winds in Canada through Rossby wave dynamics. These exacerbated dry and hot conditions create a favorable environment for the ignition and spread of fires, thus contributing to the prolonged and extreme fire season in Canada. These teleconnections can extend to decadal scales and have important implications for understanding and predicting decadal fire activity in Canada and the surrounding regions.

Wildfires serve as pivotal natural disturbance agents, exerting profound effects on biogeochemical cycles, ecosystem structures, and hydrological dynamics in various ecological system ( 1 ). Canada, renowned for its extensive forest coverage and diverse array of tree species, has experienced substantial wildfire occurrences resulting from both human activities and lightning strikes ( 2 , 3 ). This region has witnessed a notable increase in fires of both natural and anthropogenic origins in boreal spring and autumn, with the most catastrophic wildfire season on record observed in late spring to summer in 2023. As of the end of 2023, the cumulative land area devastated by wildfires in Canada has exceeded seven times the annual average and double the previous maximum in 1989 ( 4 ), emitting more than doubled Canada’s planned cumulative anthropogenic emissions reductions in 10 y ( 4 , 5 ). Moreover, the smoke associated with the burning has traveled as far as Eastern United States or even Europe, exerting serious impact on the ecosystems, public health, and biological communities globally ( 5 ). Additionally, there are indications that certain regions of Canada have witnessed an increase in area burned, the number of fires, seasonal fire severity, extreme weather events, and fire season durations in recent decades ( 4 – 8 ). Against the backdrop of climate change and other anthropogenic influences on forests and fire regimes, wildfires in Canada have become a major climate and environmental concern ( 9 – 11 ). Therefore, it is essential to understand the underlying mechanisms that contribute to these fires, especially those associated with climate variability. Wildfires are mainly triggered by abnormal weather conditions, especially droughts and heatwaves ( 8 ). These extreme weather events are caused by a combination of factors including ocean circulation patterns, positive geopotential height anomalies, and climate change. The above factors interact both spatially and temporally to increase fuel flammability, which in turn affects Canada’s fire activity indirectly ( 12 ). Similarly, the unprecedented burning season of 2023 in Canada is also believed to be associated with abnormal weather conditions, including high temperatures, low precipitation, and stronger northerly winds. These conditions are formed through a complicated interaction between remote forcing and local processes ( 5 ). While global warming increases the likelihood of these extreme events ( 13 – 15 ), the particular climate variability that causes the abnormally high fire-prone weather conditions in the late spring to summer season of 2023 in Canada remains unclear. Canadian weather can be influenced by both local and remote climate variability. In particular, ocean variability, such as those of North Atlantic, the Arctic, and Pacific ( 16 – 19 ), can remarkably impact Canadian climate through atmospheric teleconnection mechanisms. For example, statistical analyses have also presented compelling evidence on the role of warmer North Atlantic in shaping hotter summer of Canada ( 18 ). Meanwhile, diminished Arctic sea ice concentration (SIC) has substantially impacted the regional climate of Canada, with the preceding decrease in sea ice in the Arctic being associated with intensified droughts and heatwaves during summer ( 17 , 19 ). This teleconnection is maintained by wave-train structures, which are persistent from spring to summer. Previous studies have also identified the significant role of the positive phase of El Niño Southern Oscillation and Pacific Decadal Oscillation on intensifying Canadian fire activities of the following year by modulating the strength and position of western Canadian continental ridge ( 17 ). However, the extreme fire season in 2023 is unlikely to be related to the El Niño climate pattern because its effects are not expected to manifest in the summertime ( 20 ). Having said the above, it is of great importance to investigate and clarify the key climate variability that drives the abnormal weather conditions and extreme fire events in Canada this year. In this study, we focus on ocean variability and identify the North Atlantic and Arctic as the major drivers of the abnormal summer 2023 climate conditions that favor the ignition and spread of wildfires in Canada. We have designed a comprehensive approach that includes multisource data analysis and climate model simulations to reveal the underlying mechanisms connecting this remote variability with Canadian fire weather. This research is of great importance for improving the fire near-term prediction ability and adaption and prevention ability to fire of the local government. We further anticipate that our findings will advance our knowledge about the variables influencing fire weather conditions in Canada, thereby improving wildfire modeling and forecasting efforts.

Alex Ignatov added a reply:

16 hours ago

Abbas Kashani I would recommend you a chapter

Chapter Climate Change and Cultures of Environmental Migration in Ea...

There is a historical look at climate changes that may be useful to find correlation in weather patterns in different regions.