Forest fire smoke boosts ocean life - but with a hidden cost

Fires sweep through forests, darkening skies and sparking conversations about smoke pollution, health, and lost trees – but few of us picture how this may affect life in the ocean.

Every smoke plume carries tiny particles and nutrients that fall into the sea and quietly reshape life below the waves.

In a new study, led by a team at the Barcelona Supercomputing Center (BSC-CNS), scientists traced the smoke-ocean link with advanced climate models.

The results point to a future in which rising temperatures bring more fires in the far north and, with them, more iron-rich dust for the North Atlantic.

Fires as a source of ocean fertilizer

Fires loft bits of burned wood and soil into the upper air. Winds push those particles across continents and oceans. When they land, the particles deliver iron – an essential micronutrient that is in short supply in many parts of the sea.

With the additional iron, phytoplankton can bloom just as crops respond to fertilizer. The plankton draw carbon dioxide (CO₂) from the air as they grow, which links forest flames on land to the global climate balance.

Professor Carlos Pérez García-Pando is co-leader of the BSC’s Atmospheric Composition group and senior co-author of the study.

“Climate-driven fires arise from more favorable weather conditions for fire, such as low humidity and high temperatures, which in turn are influenced by anthropogenic climate change,” noted Professor García-Pando.

“Understanding these fires and their impact on the fertilization of key ocean regions, like the North Atlantic, is essential for more accurately predicting future atmospheric CO₂ levels.”

Forest fire smoke and ocean life

The researchers ran high-resolution simulations to study changing weather patterns, vegetation, and emissions. They found that by the late 21st century, climate change could push boreal wildfires to release 1.8 times more iron than today.

In North Atlantic zones where iron is scarce, that extra supply could raise summer phytoplankton productivity by as much as 40 percent.

Smoke-borne iron is only one piece of the nutrient puzzle. Warming oceans are expected to reduce the upwelling of other key nutrients in many regions. That drop could blunt some of the carbon-absorbing benefit of new phytoplankton growth.

“Quantifying this nutrient source for phytoplankton is important for gaining a more precise idea of how much CO₂ will remain in the atmosphere in the coming decades,” said Elisa Bergas-Massó, BSC-CNS researcher and lead author of the study.

“By determining how climate-driven fires will increase the supply of iron to the ocean, we are revealing a crucial feedback loop in the Earth system that we must understand to address climate change.”

Estimating future CO₂ levels

Fire science, atmospheric chemistry, oceanography, and climate policy often move on separate tracks. This study pulls them together and shows why that matters. Accurately estimating future CO₂ levels depends on knowing how land fires fertilize the sea.

Study co-senior author Maria Gonçalves Ageitos is a researcher at the BSC and the Universitat Politècnica de Catalunya (UPC).

“The results of this study are crucial for improving projections of the carbon cycle and ocean health under a changing climate, paving the way for more accurate climate models and better-informed future climate change adaptation policies,” said Gonçalves.

The authors call for better observations of smoke plumes, ocean nutrient levels, and phytoplankton blooms, along with finer-scale modeling.

Each improvement will tighten the numbers on how much carbon the ocean can pull from the air – and how forest management, fire prevention, and emissions cuts on land might echo across the planet’s largest ecosystem.

Earth’s hidden connections

In a warming world, nothing exists in isolation. Climate change doesn’t just melt ice or just raise sea levels – it alters winds, shifts fire seasons, changes ocean chemistry, and influences the tiniest organisms at sea.

This study is one more example of how deeply connected Earth’s systems really are. Fires in distant forests can influence life and carbon absorption in the ocean. What happens on land doesn’t stay on land.

As the climate continues to change, we need to pay closer attention to these hidden links – because solving one part of the puzzle means understanding how it fits into the whole.

The full study was published in the journal Nature Climate Change.

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