Studies have shown that forests emit carbon dioxide for years after fires.

A recent study found that forests destroyed by fires continue to emit carbon dioxide (CO₂) for years after the flames have died down. The boreal forest, a critical CO₂ sink spanning the Earth’s northern latitudes, plays a key role in removing carbon from the atmosphere. But when these forests burn, they release large amounts of CO₂, which exacerbates climate change.

Impact of forest fires on boreal forests

Research conducted in central Sweden after the extreme forest fires of 2018 showed that burned areas continue to release CO₂ long after the fires have gone out. This continued emission is significant because it doubles the amount of CO₂ released during the fire itself. The researchers measured the exchange of CO₂ between land and atmosphere over four years, comparing burned and unburned regions, as well as areas subjected to different post-fire management strategies.

Emissions and Fire Recovery

In the study, areas where trees were killed by fire or removed through emergency logging emitted an average of 650 grams of carbon per square meter over the first four years. By comparison, an unburned forest of a similar size would typically remove 1,200 grams of carbon from the atmosphere over the same period. The results suggest that a burned forest could take more than 40 years to recoup the CO₂ lost in the fire.

The Role of Post-Fire Management

The study also highlighted the importance of post-fire management in forest recovery. Practices such as emergency logging and soil plowing, which are common in Sweden, slow down regrowth. This delay makes it harder for the forest to become a CO₂ sink again. On the other hand, leaving surviving trees allows them to continue to capture carbon, albeit at a reduced rate.

Implications for climate modeling

The study highlights the need to rethink forest management practices as wildfires become more frequent due to climate change. It also calls on climate modelers to consider prolonged CO₂ emissions from burned forests when assessing the environmental impacts of wildfires.