To the many problems caused by wildfires, add reduced solar generation and more use of fossil fuels as a result. A study of the 2023 Canadian wildfires has concluded that drifting smoke caused a 3 per cent drop in solar power generation in both Europe and North America, costing nearly $2 billion.
鈥淚t鈥檚 clear that we are facing a situation where this is going to keep happening,鈥� says Iulian-Alin Ro葯u at the Technical University of Crete in Greece. 鈥淚t seems like every year from now on, we are going to have some relatively significant Canadian wildfire events.鈥�
Smoke from large wildfires in Canada can spread across much of the northern hemisphere, reducing how much sunshine reaches the ground. Last year, Ro葯u reported that so much smoke was released during the massive 2023 wildfires in Canada that it reduced summer temperatures across the hemisphere by nearly 1掳C 鈥� which still wasn鈥檛 enough to stop 2023 being the hottest year on record, now surpassed by 2024.
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He recently discussed his findings with fire expert at the University of East Anglia in the UK. 鈥淲e were looking at pollution maps and Matthew, out of nowhere, says, well, hang on a second, I wonder what this does to solar power production,鈥� says Ro葯u.
So Ro葯u, Jones and their colleagues got data on solar generation in North America and Europe and plugged it into the climate model Ro葯u used for his 2025 study. Their study takes into account the fact that the cooling effect of smoke slightly compensates for less sunshine by increasing the efficiency of solar panels 鈥� by 20 per cent in Europe, for instance.
Based on electricity prices at the time, the team calculates that North America 鈥� mainly the US 鈥� lost $711 million, while Europe lost almost $1.17 billion, with Germany being hit hardest. The reason why Europe lost more is largely that electricity prices are higher there, says Ro葯u, plus most solar generation in the US is in southern and western states that were less affected by smoke.
The impact of the smoke was greater than the researchers expected, he says. 鈥淎 whole bunch of solar power was not being produced, and that led to increased CO2 emissions, because obviously the rest of the energy industry had to compensate.鈥�
鈥淭here needs to be more understanding of the fact that fire can affect pretty much everything: pollution, health, weather and even solar power,鈥� he adds.
With smoke from Canada reaching Europe again this year, the same thing is happening again. 鈥淚 have seen some relatively worrying data for this year as well,鈥� says Ro葯u. But with the season still ongoing, he says it鈥檚 too early to compare with 2023.
Communications Earth & Environment DOI: 10.1038/s43247-026-03860-x
