A forest fire rages in British Columbia, Canada in June 2023
Imago / Alamy Stock Photo
2023 broke the hottest record for the year, but it could have been even warmer. The whole northern hemisphere would have been almost 1 ° C heating on average during its summer without the cooling effect of massive forest fires in Canada, suggests a climate model. Smoke may also have led to the driest in August from India.
“I think it is really difficult to understand how gigantic the fires were. It was crazy, ”explains Iulian-Alin Rosu at the Technical University of Crete in Greece, who presented the conclusions of his team at a meeting of the European Union of Geosciences in Vienna, Austria.
The emissions were approximately five or six times higher than those during any forest season previously recorded in Canada, said Rosu. The carbon dioxide of these fires has a continuous warming effect, but in 2023, this warming was offset by the cooling effect of sunlight blocking smoke.
To estimate the quantity of smoke cooling, Rosu and his colleagues organized a series of climate model simulations with and without Canadian forest fire emissions. The results suggest that between May and September, the smoke caused local cooling up to 5.4 ° C (9.7 ° F) in small parts of Canada and that the northern hemisphere as a whole was 0.9 ° C (1.6 ° F) cooler.
This may seem surprising since some parts of Canada have experienced record temperatures during this summer. But heat records were mainly in Western regions, explains Rosu, while smoke blew to the east and had the largest cooling effect on this side of the country.
The impacts were not limited to Canada. In the model, forest fire shows have led to changes in the winds on Asia which weaken the monsoon and led to less precipitation in India – and that is what happened in reality.
“The precipitation anomaly that is observed in the data is really, really close to what we see in our model,” explains Rosu. This is an indication that the model has done a very good job, he said.
However, the cooling effect did not last long. “When I examined the data for November and December, there was really not much effect,” explains Rosu.
The record set in 2023 for the hottest year did not last longer – 2024 proved to be even warmer.
Subjects:
