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3. OIF (Ocean Iron Fertilization) using Biogenic Iron
••••••The oceans occupy three fourths of the area of the earth and have already been shown to sequester 38 trillion tons of carbon dioxide by natural processes. The science and issues involved in fertilization and nourishment of the oceans have been extensively reviewed in the section of this web site entitled: Role of the Ocean in Combating Climate Change. One item reviewed was the rate of natural deposition of iron into the oceans by aeolian (dust storm) means.
••••••Studies of Petit, et al (1999) estimated that 14 million metric tons of aeolian iron are deposited in the world’s oceans each year. While there have been many who have voiced concerns about OIF, it is very unlikely any iron fertilization project would ever come close to putting the amounts of iron into the ocean that occur naturally. This strongly suggests that concerns about iron fertilization of the ocean are over blown.
••••••By contrast, planting trees has been touted by many environmental groups as the solution to climate change. However, recent detailed studies by Sullivan, et al, 2020 of over 500,000 trees in subtropical forests have shown that while they are capable of continuing to store CO2 despite increasing global temperatures, there is a finite limit to this ability. When temperatures reach 2oC over pre-industrial temperatures, trees will begin to release by respiration more CO2 than they consume by photosynthesis (Sullivan, et al, 2020; Pennisi, 2020). This would clearly qualify as one of the tipping points discussed in the section of this web site entitled, Global Warming is Real. Modeling shows that with business as usual the earth’s temperature could reach 2oC over preindustrial era by 2063.
••••••This suggests that all the trees on earth may be useless as a CO2 sink by 2063. Not good news. In contrast to trees, marine phytoplankton don’t burn and don’t release carbon stored on the bottom of the ocean at higher atmospheric temperatures. This suggests that despite some of the objections to ocean fertilization we should take this approach very seriously. In a recent paper entitled - Biogenic Iron Dust: A Novel Approach to Ocean Iron Fertilization as a Means of Large-Scale Removal of Carbon Dioxide from the Atmosphere, Emerson (2019) proposed the use of biogenic iron for iron fertilization projects. His idea was to take advantage of nanoparticulate, poorly crystalline Fe-oxides produced by chemosynthetic iron-oxidizing bacteria (biogenic iron), as an iron source to fertilize the ocean.
••••••Emerson (2020) stated that “Upon drying, these bacteria generated oxides produce a fine powder that could be dispersed at altitude by aircraft to augment wind-driven aeolian dust that is a primary iron source to the open ocean. Based on Fe-oxidation rates for natural populations of iron-oxidizing bacteria it was estimated that 1,500 hectares of production ponds (1 × 100 × 100 m) would be required to produce sufficient iron dust to supply the 30% of the global ocean that is iron-limited. Addition of biogenic iron to meso-scale eddies could provide an effective means of testing this process.
••••••In studies of the cost of OIF Harrison (2013) found that even using a relatively small ship it costs about $8,000 per day to run, and these projects average one month each, for a total of approximately a quarter of a million dollars per episode. Emerson’s proposal of using very fine biogenic iron dust dispersed from airplanes or helicopters, has the feel that it might reproduce the natural effects of aeolian dust. Fertilizing the ocean using this technique
would probably require renting a plane at possibly $10,000 for each pass. Four passes for $40,000 could be as effective as a month’s tour by boat.
••••••Since there are many unknowns, any such effort will require research and development integrated across oceanographic and earth science disciplines, to determine its long term efficacy and cost effectiveness.
••••••The Comings Foundation will sponsor grants, or fund Emerson, to explore this unique method of iron fertilization of the ocean. These projects should attempt to incorporate the studies suggested by Buesseler et al, (2008) that would help to validate iron fertilization as a partial solution to global warming.

REFERENCES See references section of Role of the Ocean in Combating Climate Change