Iron Fertilization

Iron fertilization is the addition of dissolved iron to surface water to relieve iron limitation and stimulate phytoplankton growth, tested as a way to draw down atmospheric CO2. It targets high-nutrient, low-chlorophyll regions, the Southern Ocean, equatorial and subarctic Pacific, where nitrate and phosphate stay high but trace iron is scarce. More than a dozen mesoscale experiments since IronEx in 1993 confirmed blooms follow iron addition, yet measured carbon export to depth was small and short-lived. The efficiency, ecological side effects, and verification problems leave it scientifically contested and excluded from accepted mitigation under the London Convention and Protocol.