Canada’s Major Wildfires Contributed to Global Cooling in 2023

2023 set new records as one of the hottest years, but it could have been even warmer. Climate models indicate that without the cooling effect of smoke from large wildfires in Canada, the average summer temperature in the Northern Hemisphere would have been approximately 1°C higher. Smoke may also be present in August, India’s driest month.

“It’s difficult to grasp the scale of such a massive fire. It was extraordinary,” remarks Iurian Allyn Roz from the Crete Institute of Technology in Greece.

According to Rosu, emissions from wildfires this year were estimated to be five to six times higher than those recorded during previous wildfire seasons in Canada. Although carbon dioxide from these fires contributes to warming, in 2023, this warming was offset by the cooling effects of the smoke blocking sunlight.

To quantify the smoke’s cooling impact, Ross and colleagues conducted a series of climate model simulations, comparing scenarios with and without emissions from Canadian wildfires. The findings suggest that between May and September, smoke caused local cooling up to 5.4°C (9.7°F) in certain areas of Canada, leading to an overall cooling of 0.9°C (1.6°F) for the Northern Hemisphere.

This might be unexpected given that record temperatures were reported in parts of Canada that summer. However, while the heat was mostly concentrated in the west, Ross explains that the smoke drifted eastward, where it had the most significant cooling effect.

The effects extended beyond Canada as well. In this model, emissions from wildfires altered wind patterns in Asia, diminishing the monsoon and reducing rainfall in India. This aligns with actual observed phenomena.

“The precipitation discrepancies observed in the data closely resemble those predicted in the model,” notes Rosu, affirming the model’s accuracy.

Nonetheless, the cooling effect proved to be short-lived. “Data analysis for November and December showed minimal impact,” says Rosu.

The record for the hottest year of 2023 may not last long, as 2024 is shaping up to be even hotter.