Extratropical Forest Fire Emissions Surge with Climate Shift

As climate change promotes fire-favorable weather, climate-driven wildfires in extratropical forests have overtaken tropical forests as the leading source of global fire emissions, researchers report. The findings raise urgent concerns about the future of forest carbon sinks under climate change. Fire has long played a role in shaping Earth's forests and regulating carbon storage in ecosystems. However, anthropogenic climate change has intensified fire-prone weather, leading to an increase in burned areas and carbon emissions, particularly in forested regions. These fires not only reduce forests' ability to absorb carbon but also disrupt ecosystems, harm biodiversity, and pose significant societal threats. While climate, human activity, and vegetation all influence forest fire patterns, their relative importance varies by region, making it difficult to untangle the multiple controlling factors that influence wildfire trends worldwide. To better understand global fire patterns, Matthew Jones and colleagues applied a k-means clustering machine learning algorithm and grouped 414 forest ecoregions into 12 "pyromes," which are regions that share similar patterns of fire activity based on climate, vegetation, and human factors. Mapping global forest pyromes revealed significant variation in the factors that control fire extent across different forest ecoregions. While human activities dominate fire patterns in tropical pyromes, climatic factors, such as fire-favorable weather and vegetation growth, increasingly drive forest fires and carbon emissions in extratropical regions. According to Jones et al., between 2001 and 2023, forest fire carbon emissions grew by 60%, with extratropical pyromes now surpassing tropical forests in contributing to fire-related carbon emissions. The findings suggest a potential destabilization of carbon stocks in some extratropical forests, underscoring the critical role of climate change in shaping global fire regimes and the necessity of addressing emissions to safeguard forest carbon sinks.