1123. Increase in Greenhouse Gas Emissions from Forest Fires Related to Climate Change

Anthropogenic climate change has made forest fires bigger, more intense, and more common. However, various factors are involved in forest fires, and it is often difficult to analyze the causes.

The paper, published in the journal Science, used a machine learning approach to identify the "why" and "where" of increased forest fire observations. The authors identified different forest ecoregions, classified them into 12 global forest pyromes, and analyzed differences in sensitivity to climate, anthropogenic factors, and vegetation.

The authors found that emissions of forest fires in the extratropics have increased significantly under climate change. Fire emissions at one pyrome, which straddles the boreal forests of Eurasia and North America, almost tripled between 2001 and 2023. This increase was associated with fire-friendly weather conditions, a decrease in soil moisture, and an increase in vegetation productivity. In contrast, tropical pyromes showed a decrease in fire emissions due to reduced deforestation in humid tropical forests on the one hand, and fragmentation of dry tropical forests due to agriculture and other land use on the other. Overall, carbon emissions from forest fires increased by 60% globally during the study period, with the extratropics being the largest contributors.

Compared to human activities, which are the biggest contributors to fires in tropical regions, the increase in fires in the extratropics highlights the strong influence of climatic factors. The increase in carbon emissions from forest fires was explained by both changes in the extent of fires and changes in the severity of fires (measured in carbon emissions per unit area burned by fires). As the climate warms and droughts become more frequent, it is estimated to be affecting drier and more flammable plant fuel stocks.

The sharp trend of increasing emissions of forest fires in the extratropics suggests that forest carbon stocks are becoming increasingly vulnerable to climate change, reducing the ability of forests to act as carbon sinks in climate action. In order to mitigate these risks, effective forest management and policies aimed at reducing greenhouse gas emissions are essential. The study highlights the importance of considering regional differences in fire control when developing strategies to manage fires and protect forest ecosystems.

Reference
Matthew W. Jones, Global rise in forest fire emissions linked to climate change in the extratropics, Science (2024). DOI: 10.1126/science.adl5889. www.science.org/doi/10.1126/science.adl5889　

Contributor: IIYAMA Miyuki, Information Program