The Concept of Ocean Iron Fertilization: Adding tiny amounts of iron to nutrient-rich, iron-poor waters sparks phytoplankton blooms. These plants absorb CO₂, fuel food webs, and send some carbon into the deep ocean for centuries.
Science of Ocean Iron Fertilization (OIF)
Iron is a small but powerful driver of ocean life and climate regulation.
Carbon Partitioning: After blooms, part of the captured carbon sinks as particles into deeper waters, where some remains stored long-term and helps regulate climate.
Natural Iron Sources: Ice melt, rivers, vents, dust, fires, and upwelling all supply iron to the sea, fueling natural productivity and carbon drawdown.
Iron Bioavailability: Less than 1% of ocean iron is dissolved and usable. Its availability depends on chemical forms and conditions.
HNLC Regions: One-third of the ocean is iron-limited. Southern Ocean, Equatorial Pacific, and Subarctic Pacific are prime OIF zones.
Coastal Upwelling: Winds lift cold, nutrient- and iron-rich waters. These areas sustain fisheries and natural blooms.
Atmospheric Deposition: Dust, smoke, and human emissions drop soluble iron onto the ocean, varying by region and season.
Global Observations: Ship surveys map dissolved iron across depths and seasons, showing its scarcity and importance.
Modelled Distribution: Models show surface waters are iron-poor while deep waters are richer, highlighting fertilization hotspots.
Deep-Ocean Iron: At 3,000–3,500 m, iron is relatively steady but varies by basin, with the Southern Ocean lower.
Iron, though scarce, drives ocean life and climate balance. With careful, monitored use, OIF could boost carbon capture within a safe mCDR portfolio.