California’s record fires have been fueled by millions of hidden dead trees

California’s record fires may have been fueled by millions of hidden dead trees, according to a new study.

Scientists from the University of Copenhagen studied the 2020 wildfires, applying artificial intelligence (AI) to aerial photos to create a dataset of trees across the country.

They found that individual and clustered tree death was widespread among living trees. This presents a brand new explanation for the severe fire season, published in Nature Communications.

California’s 2020 wildfire season was one of the most destructive in state history, with unprecedented scope and intensity. Over 4.2 million acres burned, marking a record year for fire damage. The fires are believed to have been fueled by a combination of factors including extreme heat, prolonged drought and strong winds, all exacerbated by climate change.

However, research into the causes of the fires is still ongoing, as knowing the contributing factors will help mitigate the risk in the future.

Using an optimized AI model applied to high-resolution aerial photos, researchers mapped the health of trees across California, covering over 90 million trees with unprecedented precision. This detailed map revealed a small number of dead trees, all of which had a specific characteristic.

“Our data shows that a large amount of these trees are isolated or located in small groups of only a few trees, which has allowed them to be hidden scattered among healthy and living trees by high-resolution satellite images thick. This is new knowledge,” Stéphanie Horion of the University of Copenhagen’s Department of Geosciences and Natural Resource Management, who worked on the study, said in a statement.

Horion added that the rapid spread of the 2020 fires was linked to the “uneven distribution of fuel in both density and flammability”.

“This makes it reasonable to speculate that such scattered enclaves of dry dead trees may have acted as kindling between live trees, influencing the intensity and spread of fires. This new knowledge is also interesting as part of possible explanation for the violent fires in California, but also a lot for our efforts to understand the phenomenon of tree death in general,” said Horion.

During the 2020 wildfires, thousands of structures were destroyed and many communities were evacuated, resulting in widespread displacement and significant economic loss. The fires also had severe environmental impacts, including degraded air quality that affected millions of people and widespread habitat destruction. The 2020 season highlighted the urgent need for comprehensive wildfire management strategies and climate resilience planning in California.

The researchers did not actually intend to investigate wildfires in their study. Rather, they were looking for more information on the mass death of the tree and why it happens. They found that it is becoming more common and widespread as climate change worsens.

“New data shows that drought and subsequent insect attacks are the biggest killers in forests. Fire may follow as an indirect consequence,” Horion said.

“For a fire to break out, three basic elements are necessary: ​​hot, dry weather and climatic conditions that climate change has increased in frequency, an ignition source – such as a lightning strike or a careless person – and finally, an abundance of combustible materials Drought weakens the ‘immune system’ of trees, which increases the risk of tree mortality after bark attacks and dead trees burn well.

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