As climate change progresses, wildfires in the Northern Hemisphere are expected to nearly double the amount of smoke particulates and nutrients like iron in the atmosphere. This increase could significantly impact how carbon dioxide is stored and released by affecting ocean productivity, particularly in the North Atlantic.
An international research team utilized computer models to examine both climate and human-induced fire drivers across various socio-economic scenarios. They discovered that climate change alone could increase fire-driven iron emissions by 1.7 to 1.8 times compared to human activities alone, with differences noted between hemispheres.
“Fire is an important part of the Earth’s overall ecosystem, and it’s connected to many things that seem distant from it, including CO2 storage in the oceans,” stated Elisa Bergas-Masso, a research scholar at North Carolina State University and corresponding author of the study. The research was conducted during her doctoral studies at the Barcelona Supercomputing Center in Spain.
Wildfires release a highly soluble form of iron into the atmosphere, which then deposits into oceans. Soluble iron is crucial for phytoplankton growth in open oceans; thus, increased supply can enhance photosynthesis and carbon sequestration as these organisms die or are consumed by zooplankton.
The models also indicated regional differences in how climate-driven fires might affect iron deposition in oceans. In the North Atlantic, increased iron levels could boost productivity by up to 20% annually (and up to 40% during summer’s fire season), provided other necessary macronutrients remain stable. Even if these nutrient levels decline, increased iron could offset losses by up to 8%.
In contrast, in the Southern Hemisphere where human activities like fossil fuel emissions also contribute significantly to oceanic iron deposition, climate-driven fires may counterbalance reduced human activity due to improved air quality or land management practices.
“Fire is a destructive but essential part of maintaining the health of Earth’s extremely complex and interconnected ecosystem,” said Douglas Hamilton, assistant professor at NC State and co-author of the study.
Hamilton emphasized that “models like this help us determine how future changes in fire regimes will influence other parts of the Earth System.” He added that recent extreme events suggest we might already be exceeding projected increases in fire-iron emissions.
The study appears in Nature Climate Change and received support from entities including the European Research Council and NASA (grant 80NSSC24K0446). Contributors include María Gonçalves Ageitos and Carlos Pérez García-Pando from Barcelona Supercomputing Center; Stelios Myriokefalitakis from National Observatory of Athens; and Sagar Rathod from University of Wisconsin-Madison.
