Climate Change and Terrigenous Inputs Decrease the Efficiency of the Future Arctic Ocean’s Biological Carbon Pump
- Hakan Sener
- Mar 26
- 3 min read
Updated: Apr 9
A 2025 study finds Arctic carbon sequestration efficiency may drop 40% by 2100 due to climate change and rising land-based nutrient inputs.
The Arctic Ocean is undergoing rapid and profound climate transformations, with increasing nutrient inputs from rivers and coastal erosion. While primary production is expected to rise in the coming decades, this study reveals an unexpected decline in the Arctic’s biological carbon pump (BCP) efficiency, reducing its ability to sequester atmospheric CO₂.
Using a high-resolution ocean biogeochemistry model, the researchers project that by 2100, the efficiency of the Arctic BCP will decline by 40%—a result of intensified remineralization, CO₂ outgassing, and ecosystem changes. The study highlights the crucial but often neglected role of terrigenous inputs (carbon and nutrients from land), which further reduce the Arctic’s carbon sink by at least 10%.
Key Findings: A Declining Arctic Carbon Sink
Climate Change Reduces Carbon Sequestration by 40%
Although primary production (NPP) is projected to increase by 75%, the Arctic’s biological carbon pump will lose efficiency as warming accelerates organic matter degradation.
Increased remineralization will lead to higher CO₂ outgassing, weakening the ocean’s capacity to act as a carbon sink.
Rising Terrigenous Inputs Further Decrease CO₂ Storage
More nutrients and organic carbon from river runoff and coastal erosion will enter the Arctic Ocean.
Instead of enhancing carbon sequestration, these inputs will drive intense CO₂ outgassing, reducing the Arctic’s net carbon sink by at least 33 TgC per year (10%).
A Shift Toward a More Respired, Nutrient-Limited Arctic Ocean
While NPP is increasing, so is plankton respiration and remineralization, meaning more organic carbon is being recycled in surface waters rather than stored at depth.
Nutrient limitation is becoming the new bottleneck for Arctic productivity, reducing long-term carbon sequestration potential.
The Feedback Loops Weakening the Arctic Carbon Sink
The study identifies two competing feedback mechanisms:
Expected Negative Feedback (Stabilizing Influence)
More light and nutrients → More primary production → More carbon export → Greater atmospheric CO₂ uptake.
Unexpected Positive Feedback (Destabilizing Influence)
More organic carbon → Higher respiration → More remineralization → More CO₂ release into the atmosphere.
This positive feedback is outcompeting the expected stabilizing effects, leading to a net decline in carbon sequestration.
Implications for Climate Change and Carbon Budgets
The Arctic Ocean’s Role as a Carbon Sink is Shrinking
Current climate models may be overestimating the Arctic’s long-term ability to absorb CO₂.
The projected 40% loss in sequestration efficiency could weaken global climate mitigation strategies.
Terrigenous Inputs Should Be Integrated into Climate Models
Most IPCC-like models do not account for terrigenous carbon and nutrient inputs, leading to inaccurate carbon cycle predictions.
This study calls for urgent updates to Earth system models to improve climate projections.
Need for Arctic-Specific Climate Policies
As the Arctic transitions toward a nutrient-limited system, its ability to support marine life and store carbon will decline.
The study stresses the importance of preserving permafrost and limiting coastal erosion to prevent further CO₂ emissions.
Conclusion: A Critical Tipping Point for the Arctic Carbon Cycle
Contrary to previous assumptions that higher primary production would strengthen Arctic carbon sequestration, this study shows that climate change and terrigenous inputs are working together to weaken the Arctic’s biological carbon pump. By 2100, 40% of its efficiency may be lost, and coastal CO₂ outgassing will further erode its role as a carbon sink.
These findings underscore the urgent need to reconsider how the Arctic fits into global carbon budgets, as its transition from a CO₂ sink to a potential CO₂ source could accelerate global warming beyond current projections.
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