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Home , CLAW hypothesis, Iron fertilization

COMMERCIAL FERTILIZATION: READY FOR THE OFFSET MARKETS?

Justin Felt, Daniel Fishman, Daniel Horton, and Karla Knudson University of Michigan, Ann Arbor, MI, 48109, USA

Abstract

Ocean refers to the commercial scheme to sell carbon offsets generated by stimulating algal blooms in the open ocean. Ocean accounts for half of the yearly global primary production. In large areas of the ocean, primary production is lower than would be otherwise expected due to acute iron limitations on growth. A fortuitous byproduct of the scientific exploration of the role of aeolian deposition on primary , iron fertilization experiments have demonstrated that fertilizing small patches of the ocean with 1-3 tons of dissolved iron stimulates blooms of phytoplankton. The potential of these blooms to export carbon from the surface ocean and “sequester” it in the deep sea has drawn commercial interest due to the recent establishment of voluntary markets. Increased phytoplankton populations potentially pose a number of ecological problems, and the overwhelming water quality management imperative of the last 50 years has been diminishing algal blooms by reducing anthropogenic fertilization of aquatic . Current studies suggest that phytoplankton blooms in the open ocean do not export carbon in a predictable manner, and less than 1% is ever permanently sequestered. Significant advances in the scientific understanding, political and legal framework, and business model are necessary if ocean iron fertilization schemes are to be successful. This paper examines the scientific and economic rationale underlying ocean iron fertilization and the pratfalls therein. We conclude that the utilization of ocean iron fertilization technologies in carbon offset mitigation schemes is premature, though the nascent state of the science demands continued research and development.

1 INTRODUCTION

The rise in atmospheric carbon dioxide (CO2) concentrations since the industrial revolution has been definitively linked to the anthropogenic release of combustion reaction gases driven by the burning of fossil fuels (IPCC Report, 2008). The role of atmospheric CO2 in driving global is complex, but the preponderance of scientific evidence tightly links CO2 concentrations to global temperature and climate (Royer, 2006). As a mitigation strategy to avoid harmful repercussions from altered global climate, strategies to increase global sinks of biological CO2 are being explored (Dilling -1 et al., 2003; Pacala et al., 2004). Approximately 105 Gt yr of CO2 are removed from the -1 by (Field et al., 1998), while 23 Gt yr of CO2 are released by the burning of fossil fuels1.

THE Oceanic primary production represents 1% of global photosynthetic but accounts for 50% of the carbon fixed by photosynthesis every year (Field et al., 1998). The cycling of primary production product (fixed carbon) in the ocean is referred to as the biological pump. Primary production by (phytoplankton) is consumed by higher trophic levels, which includes heterotrophs from to . The gravitational transport of carbon-rich biomass detritus ‘pumps’ fixed atmospheric CO2 below the mixed layer (~100m depth; Figure 1). As in terrestrial ecosystems, the majority of the carbon fixed is assimilated in the higher trophic levels and respired back to the atmosphere as CO2 (Martin et al., 1987). Some primary production does sink to the ocean sediments. Areal primary production rates are lower in the ocean than on land and approximately 1/5 of the ocean surface is the aquatic analog to terrestrial deserts (Boyd et al. 2007) (Figure 2). While concentrations of macronutrients ( and phosphorous) are high, productivity in these oceanic deserts is limited by a lack of micronutrients (Martin, 1990). These ocean deserts are persistent and characterized by high nutrients and low chlorophyll (HNLC). The major HNLC zones are found in the Southern Ocean, the Equatorial Pacific, and the North Pacific sub-arctic (de la Rocha, 2004). By increasing the rate of primary production in HNLC areas some companies hope to profit via carbon offset sales.

MARTIN’S HYPOTHESIS The idea of oceanic iron fertilization as a primary mechanism in the alteration of atmospheric CO2 concentrations is derived from studies of glacial-interglacial cycles. Evidence suggests that increased iron-rich dust deposition to oceanic waters may have spurred CO2 uptake in times of continental glaciation, further cooling the environment. Consequently, a reduction in dust deposition has been chronicled during the interglacial periods of the Pleistocene. Recently published data have successfully tracked this

1 http://www.eia.doe.gov/oiaf/1605/ggccebro/chapter1.html

2 regulatory capacity of iron on atmospheric CO2 over the past 800 kyrs (Figure 3, Lambert et al., 2008). Dr. John Martin established that the reason for the persistent HNLC zones of the ocean was acute iron limitation. Iron is a necessary micronutrient for phytoplankton metabolism (Martin, 1990). In phytoplankton (the planktonic organisms responsible for oceanic primary production), iron limitation is particularly problematic. Aeolian iron-rich dust deposited in the ocean sparks massive phytoplankton blooms in HNLC zones (Figure 4). In essence, Dr. Martin’s hypothesis stated that on geologic time scales, increased iron deposition during glacial periods removed 30% of the 80 ppm CO2 decrease observed during glacial maxima (Sigman, 2000). The promise of increased productivity in HNLC ocean waters through iron fertilization is rooted in the evolutionary history of phytoplankton. The limitation of iron on biological ecosystems in today’s stems from the earliest origins of life on planet Earth. The evolution of single celled organisms ~1.6 Ga occurred in an environment of low atmospheric and subsequently low oceanic concentrations. Low levels of oceanic oxygen allowed high levels of dissolved iron within ocean waters. It was under these high levels of dissolved iron that photosynthetic phytoplankton developed. As photosynthetic organisms became more prevalent, their primary waste product, oxygen, began to accumulate in the atmosphere. With the rise of atmospheric oxygen and the subsequent oxidation of dissolved iron within the , available dissolved iron levels dropped precipitously, and iron became the primary limiting micro- nutrient of phytoplankton (de la Rocha, 2004). The self-imposed evolutionary quirk that is iron limitation has persisted throughout much of geologic time. Starting in 1993, 12 oceanographic research expeditions tested Martin’s hypothesis with small scale iron fertilization experiments. For iron deposition to lead to a drawdown in global CO2 atmospheric concentrations, a net increase in the export of fixed carbon from the mixed layers of the ocean following fertilization is necessary. By adding small amounts (450-2800 kg) dissolved, biologically available iron to patches of HNLC ocean and observing the phytoplankton response (as chlorophyll concentration, a proxy for primary production), these experiments proved that iron fertilization can produce rapid, intense blooms of phytoplankton and exponentially increase carbon uptake (Boyd et al., 2007). The experimental success of ocean iron fertilization in increasing primary production in HNLC zones is drawing the attention of the private sector. There is already a growing commercial industry dedicated to generating “carbon offsets” in terrestrial forests. The timeframe of iron fertilization results (phytoplankton blooms occur over the course of days and weeks and can be captured with stunning space photography while forests grow slowly for decades) and the hypothetical maximum amount of carbon that HNLC zones could fix from the atmosphere (on the order of Gt of carbon) presents an attractive picture to investors.

CLIMOS CASE STUDY

Climos is a Valley startup attempting to commercialize large scale iron fertilization projects and convert the carbon sequestered into sellable carbon offsets. The company would release a form of iron into the open ocean from large ships and create large algae blooms that feed off the nutrients. Climos aims to quantify the carbon rich

3 detritus which descends below the mixed layer, and create carbon offsets for potential sale on the voluntary carbon offset market. The company was founded in November 2006 and is headed by CEO Dan Whaley, who previously created the pioneering internet travel company Get There. He is supported by Margaret Leinen, who serves as the Chief Science Officer. She previously served as Assistant Director for Geosciences at the National Science Foundation, were she managed a research budget of over $700M. The team in total has 8 employees.

CARBON OFFSET MARKET Climos, as a private startup company, plans to build its business around the ability to “monetize” the carbon reductions and create carbon offsets. Carbon offsets represent the equivalent of one ton of carbon dioxide that would otherwise be in the atmosphere. In this case, the case for carbon dioxide reductions depends on the level of long term into deep-ocean. Offsets can be also created through changes in behavior, through the implementation of a renewable generation, energy efficiency procedures, or incineration of greenhouse gases among others. In order to package them, offset projects need to be verified by a third party auditor, who utilizes an established “methodology” for calculating the carbon reductions and directly monitors that the project is indeed reducing greenhouse gases in the atmosphere. A methodology lays out the calculations needed to calculate the reduction. For instance, a methodology for a renewable power project would require the author to show how the project is above and beyond business as usual (termed “additionality”), the amount of power that it is displacing, and the associated carbon emissions that are now “reduced.” Once verified by the third party auditor/verifier, a project owner has the ability to create and sell this unique market mechanism. A key component of an offset from carbon sequestration is the time frame, or “permanence.” As stipulated by the , the carbon must be sequestered for at least 100 years in order to qualify as a permanent reduction. Land Use and Forestry offsets have encountered a lot of opposition for this reason, since biologically sequestered carbon in natural vegetation are part of the active carbon cycle, and can easily be released to the atmosphere if burned or cut down. In some ways, iron fertilization is similar in that there are questions surrounding the permanence, since much of the biological matter in the deep ocean will eventually circulate back up to the surface. Climos maintains that since this could be anywhere from 100 to 1,000,000 years, this should indeed qualify as an offset. These offsets can be sold in the “voluntary” or “mandatory” markets. The voluntary and mandatory markets traded 24 million and 1,600 million tons of CO2 equivalents respectively in 2006 (Hamilton et al, 2007). The total carbon market was valued at $30 billion in 2006, of which the voluntary market was roughly 3% (Capoor and Ambrosi, 2007). In the former, buyers range from businesses, events, to retail consumers, who buy them to reduce their carbon footprint. They are often used to become “carbon neutral” as part of a marketing strategy. In the latter markets, buyers are looking to reduce their footprint in order to meet a required emissions cap, as part of a cap-and-trade mechanism. Purchasing offsets can be an alternative way of meeting one’s emissions cap, since it can substitute for an allowance. Mandatory markets tend to require more rigor than the voluntary markets.

4

OFFSET CREATION AND LISCENSING Climos is currently working with Carbon Offset Company EcoSecurities and verifier Det Norske Veritas (DNV) to create a methodology for iron fertilization. The work-in-progress is still not public. These offsets would be sold primarily into the voluntary market in the short term, and may be eligible for use in future mandatory cap- and-trade policy in America and worldwide. At the moment, there is a great deal of uncertainty regarding the types of offsets (or indeed if offsets will be allowed) in the regional and future federal policy in the US. The international Kyoto Protocol does not allow offsets from this type of project until the end of the agreement in 2012, so it seems unlikely to allow it for any periods afterwards (Leinen, 2008). There is a wide variability in terms of how much carbon could be sequestered per ton of iron, but an analysis by the Woods Hole Oceanographic Institution shows the range of potential carbon created per ton of iron as anywhere between 1,000 to 20,000 tons of carbon per ton of Fe (Figure 4). Their “optimistic direct cost estimate” is that it would cost Climos $4 per ton of CO2 equivalent in direct costs to create the carbon offsets. If able to sell them onto the marketplace for $8, that would lead to generous profit opportunities as seen below in figures 5 and 6 (W.H.O.I., 2008). Climos is still in the early stages of implementing its vision. It recently received $3.5 M in venture capital funding, which will allow it to apply for a license to release the iron into the open water, as well as pay for an environmental impact statement. The license will be procured through the country from which the ship debarks, and it will hew to the London Convention for international waters. Tetra Tech will administer the environmental impact statement. They will be developing a conceptual framework for the analysis, and engage stakeholders in this arena. More importantly, they will be looking at all the various environmental effects of iron fertilization, performing a review of all peer reviewed research to see what could the effects be of iron fertilization on the ocean . Further rounds of financing will go towards preliminary demonstration projects, including ship rental, iron sulfate purchases, and measurement of carbon sequestration (Leinen, 2008). In addition, they are in the process of procuring a license to release the iron sulfate into the ocean. Under accepted regulations for international waters, dumping is not allowed. However, Climos believes that iron fertilization should not be classified as dumping, as the iron is put there in the express purpose to sequester carbon dioxide from the air and mitigate climate change. Climos is applying for the proper permits, which would need to be approved by the departure country. Permits would likely be approved under the London Convention or London Protocol, which were established in 1972 and 1996 respectively. There is much ambiguity here, so the country approving the permits will need to weigh many different factors in this decision (I.M.O., 1972).

FROM THEORIES TO PRACTICE – THE UNKOWNS

Previous iron fertilization experiments have demonstrated that the addition of the dissolved micronutrient can stimulate phytoplankton blooms in HNLC areas, and, assuming this leads to permanently sequestered CO2, business models have demonstrated that iron fertilization has great economic potential. To proceed with real-world

5 fertilizations for carbon credits, the primary assumption underlying Martin’s theory, that significant amounts of atmospheric CO2 can be permanently sequestered in sea-floor sediments, must be proven. Additionally, the potential ecological ramifications of commercial iron fertilization must be determined. If the scientific unknowns can be quantified and if ecological impacts prove benign, the practice of iron fertilization may prove to be one of many powerful geo-engineering tools in the mitigation of climate change and subsequently may prove an economically profitable enterprise. In the following sections, we summarize the unresolved scientific issues surrounding iron fertilization, including: the potential for carbon to be sequestered, factors controlling the sequestration of carbon, quantitative amounts of carbon that may be sequestered, the resources and timescales required for sequestration, and the potential side effects to and ecology.

CARBON SEQUESTRATION

FATE OF FIXED CARBON In order for CO2 to be transferred from the atmosphere to the deep ocean sediments where it can be permanently buried, it must first pass through several km of ocean water. There are three methods by which CO2 is transferred to these depths: via the pump, the physical pump, and the biological pump. The solubility pump depends on the high atmosphere-ocean gradient to diffuse CO2 into the water. The physical pump transfers CO2 to the ocean by physical mixing during down-welling to form deep-waters. However, the solubility and physical pumps may take thousands of years to bring CO2 to the seafloor. With the ability to transfer CO2 via particulate organic matter (POM) to the ocean floor within days to weeks, the “biological pump,” which Fe- fertilization targets, is the most active of these methods. Although the biological pump is most effective at transferring CO2 from the atmosphere to the ocean floor, a significant amount of particulate organic carbon (POC) originating at the surface never reaches the sediments. Using experimental data, Martin et al. (1987) demonstrated the rapid regeneration of POC into CO2 at depth (Table 1). Each year, 50-60 Pg C is fixed by photosynthesizing organisms in the surface ocean (Shuskina, 1985; Martin et al., 1987; Field et al., 1998). Of this, 16 Pg C (27-32%) is exported past the mixed layer, from the surface to the deep waters (Falkowski et al., 2000) and only 0.16 Pg C (~0.3%) finally contacts the seafloor (Hedges and Keil, 1995). Instead of sinking, POM is mostly recycled within the “nutrient loop” in the first few hundred meters of water (Martin et al., 1987; Chester, 2003). For POM export and termination in the deep ocean sediments, it must escape significant obstacles imposed by zooplankton and bacteria.

ZOOPLANKTON GRAZING Zooplankton living in the euphotic zone are detrimental to the export of POM for two reasons. First, zooplankton graze on POM, assimilating 10-40% of the organic carbon and excrete the rest as small fecal pellets (de la Rocha, 2004). The result is fewer total particles available for export and a larger faction of small particles, which sink much more slowly than the original aggregates and comprise a very small fraction of the total exported organic flux (de la Rocha, 2004). In addition, zooplankton can also decrease

6 export by splitting large aggregates into smaller particles (de la Rocha, 2004). It has been suggested that Fe-fertilization experiments, conducted over only short time periods and small areas, have been unable to demonstrate the full potential effects of grazing (Boyd et al., 2007; de Baar et al., 2005). It is possible that fertilization of a longer duration may increase zooplankton stocks, leading to diminished export efficiency (Boyd et al., 2007; de Baar et al., 2005). Additionally, developing better models of Fe- zooplankton interactions would permit an improved understanding of how these dynamics may work over greater timescales and areas. Bacterial hydrolysis Bacterial activity, which decomposes sinking POM, is another limitation to the amount of carbon that is exported. Bacteria may consume up to 80% of near-shore surface primary production (Cho and Azam, 1988). Furthermore, bacteria enzymes speed the dissolution of siliceous aggregates, leading to less exported POC (Bidle and Azam, 2001). Bacterial activity may be especially pronounced in warmer waters, which may be problematic to Fe-fertilization, since one of the two major HNLC areas is the Equatorial Pacific Ocean. Partly for this reason, scientists studying Fe-fertilization have turned their attention to the Southern Ocean, although this poses other (logistical) challenges.

EXPORT SUCCESS The limited potential for POC sequestration in the sediments, due to various fates of fixed carbon, demonstrates that the success of carbon sequestration cannot be predicted by algal blooms alone. Therefore, we must examine the amount of C that has been exported in Fe-fertilization experiments. Recently, Boyd et al. (2007) compiled the results from the 12 major Fe-fertilization experiments from 1993-2005 (Table 2). Analysis of the POC export measurements from these 12 experiments, half (six) showed “no significant change (relative to the surrounding HNLC waters)” (Boyd et al., 2007). Of the remaining experiments, five showed an increase in export (including one in which export was attributed to a “subduction event”), and one experiment (which did not produce a bloom) had no reported export measurements (Boyd et al., 2007). Thus, it appears that the absolute success (export vs. non-export) of Fe-fertilization experiments has been mixed. While five of the previous iron fertilization experiments report net increased export, we must now resolve the relative success of iron fertilization in these instances, in order to determine if iron fertilization may be a potent geoengineering fix. To accomplish this, the degree of POC export resulting from Fe additions must be calculated. To date, the most reliable export measurements have stemmed from the Southern Ocean Iron (Fe) Experiment (SOFEX; Boyd, 2004). Additionally, the location of the SOFEX fertilization sites, the Southern Ocean, is deemed to have the highest potential for carbon sequestration (Boyd et al., 2000). For these two reasons, data and interpretations of SOFEX (see Buesseler et al., 2004) hold the key to our best current understanding of carbon sequestration via iron fertilization. Significantly, SOFEX export ratios do not indicate that iron fertilization has the ability to sequester CO2 in amounts that will appreciably influence climate change. Buesseler et al. (2004) estimated that SOFEX produced a flux of about 900 tons of C 2 using 1.26 tons of Fe over a patch of 1000 km in a 21-day period. In contrast,

7 anthropogenic emissions create a flux of carbon to the atmosphere of approximately 6.5 × 109 tons each year. In comparison, the flux of carbon produced by SOFEX was “similar in magnitude to that of natural blooms in the Southern Ocean and thus small relative to global carbon budgets and proposed geo-engineering plans to sequester atmospheric carbon dioxide in the deep sea” (Buesseler et al., 2004). Feasibility and efficiency based on carbon export ratios Along with total C flux values, the amount of C sequestered per unit of Fe must be considered. Buesseler et al. (2004) found that SOFEX produced Csequestered:Feadded ratios that were very small (3.3 × 103 molar ratio at depth 250). With such a weak ability to sequester carbon, much Fe would be needed to produce an appreciable effect on the carbon budget. Based on the SOFEX export data, Zeebe and Archer (2005) calculated the feasibility (total number of ships required for fertilization and the area of ocean needing to be fertilized) of sequestering 1 Pg of CO2. First, they determined that since only 10- 25% of POC exported is actually sequestered, a total of 5-10 Pg of CO2 must be exported. Additionally, they assert that each ship can cover 1.3 × 1010 m2 of ocean (~0.02% of the total HNLC areas) and has capacity of ~20 kt. Using these calculations in combination with the Csequestered:Feadded ratios, these workers determined the following were needed for sequestering 1 Pg of CO2 per year:

1) 1,000-5,000 vessels. 2) Fertilization frequency of 77-154 times per year. 3) An area of HNLC ocean equal to 15 times the total HNLC areas (about 2 times Earth’s surface).

These calculations pertain to the removal of only a fraction (1 Pg) of yearly anthropogenic emissions (6.6 Pg). Therefore, in order for Fe fertilization to sequester the total flux of annual anthropogenic carbon, it would require 6,600-33,000 vessels and fertilization frequency of 508-1,016 times per year, over an area of HNLC equal to 13.2 times Earth’s surface. In light of these calculations, unless higher Csequestered:Feadded can be demonstrated, we cannot assume that iron fertilization is a feasible way to remove substantial amounts of atmospheric CO2, and we clearly cannot rely on it as our only alternative to business-as-usual practices.

MEASURING CARBON EXPORT Thus far, SOFEX has provided the most reliable data and was conducted in the most promising locations; yet, its success was limited. In order to prove the feasibility of geo-engineering through iron fertilization experiments, it is necessary to demonstrate much higher potential success in future mesoscale fertilization experiments. Sediment traps provide our most direct measurements of exported carbon (de la Rocha, 2004). These traps can be placed at varying depths in the water column to collect sinking POM, which is used to calculate exported carbon at that depth. Additionally, values can be extrapolated to estimate how much carbon will be exported to even deeper waters (Buesseler, 1991). Unfortunately, measurements of exported carbon from sediment traps are still unreliable and result in both over and under-estimates (10-1,000% collection efficiency; Buesseler, 1991). This discrepancy can be attributed to two factors: fluid

8 dynamics and the short sampling time. Placing sediment traps in the water disrupts normal fluid flow, creating a “hydrodynamic bias” towards collecting POM (Buesseler, 1991). Additionally, overestimates may be produced if sediment traps happen to be collected during an episodic sediment flux (Buesseler, 1991) or if zooplankton swim (rather than fall upon death) into traps (de la Rocha, 2004). In contrast, underestimates may occur if sediment traps sample during a period of episodic low particle flux (Buesseler, 1991). Therefore, longer sampling periods, models contributing better constraints on the range of trapping efficiency, as well as better designs, are all necessary for reliable export values—crucial information needed for determining the feasibility of iron fertilization for geo-engineering.

OTHER EXPORT CONSIDERATIONS While the effects of bacterial decomposition and zooplankton grazing are fairly well-known, iron fertilization experiments suggest that other, more unpredictable, factors may also limit export efficiency. For example, ocean currents, a highly dynamic aspect of iron fertilization experiments, may play a role. In SOFEX, two patches “North Patch” and “South Patch,” were fertilized with iron. While the north patch remained self-contained in a narrow strip of water (7×340 km by day 38), the south patch expanded to a much larger area (2380 km2 by day 20; Coale et al., 2004), resulting in a dilution of the bloom products that may have decreased export efficiency (Coale et al., 2004; Hiscock and Millero, 2005). Additionally, results from SOFEX demonstrate that silica limitations on phytoplankton growth also influence phytoplankton growth, and possibly thus, export efficiency (Coale et al., 2004; Hiscock and Millero, 2005). In this experiment, two sites with differing concentrations of silicic acid were contrasted to show the effects of Fe- fertilization on phytoplankton in iron-limited environments. Upon fertilization of regions of high nitirate and low silicic acid, blooms resulted that were composed of half (the only major type of phytoplankton to require silicic acid; de la Rocha, 2004) and non- siliceous phytoplankton (Boyd, 2004). In contrast, the fertilization of regions of high nitirate and high silicic acid resulted in blooms that were dominated by diatoms (Boyd, 2004). Unfortunately several external factors prevent a direct comparison of export in this experiment (Boyd, 2004). However, theoretically, diatoms should increase the efficiency of the biological pump due to their large size, which facilitates sinking (de la Rocha, 2004). Silicic acid concentrations are an important consideration in interpreting results from previous iron fertilization experiments, such as the Southern Ocean Iron Release Experiment (SOIREE) and the Eurpoean Iron Fertilization Experiment (EisenEx), and predicting iron fertilization potential. Neither of these experiments produced a significant change of C export (Boyd et al., 2007), although these experiment sites were areas of moderate silicic acid concentrations (Figure 7; Hiscock and Millero, 2005). If we cannot demonstrate significant carbon export in moderately silicic waters, it is unpromising that we could export high amounts of carbon from low silicic acid waters, which cover most (65%) of the Southern Ocean (Figure 7; Hiscock and Millero, 2005).

9 ECOLOGICAL IMPACTS

Studies of the effect of iron fertilization on the ocean’s ecology are currently limited in both scope and level of completion. Those studies which have examined the effects of iron fertilization within the are still grappling with the fundamental understanding of nutrient uptake and carbon sequestration by phytoplankton. In this respect, all published studies examine only the effects of iron fertilization on the base of the , phytoplankton, and do not delve beyond the primary producers into changes in higher order organisms, such as higher trophic zooplankton and . Additionally, the temporally restricted of these studies does not allow for an examination of the long term effects of iron fertilization on trends within the oceanic ecosystem. Uncertainties remain with regard to the effects of downstream macronutrient removal, phytoplankton over-population, and biologically induced non-CO2 (Buesseler et al., 2008; Chisholm et al., 2001). Assuming the sequestration of carbon in ocean sediments is readily achievable via the addition of dissolved iron to the water column, there remain significant questions related to the ecosystem as a whole. Phytoplankton’s role as the base of the food web is particularly troubling. A disruption or collapse of this system would have far-reaching effects throughout the world’s oceans.

REDFIELD RATIO The base of oceanic ecosystems, phytoplankton, rely on an evolutionarily proscribed macro-nutrient stoichiometry, called the . The Redfield ratio indicates that the gross mass of phytoplankton organic matter is composed of carbon, nitrogen, and phosphorous in an average molar ratio of 106C:16N:1P. Recent studies suggest that while the addition of the micro-nutrient iron does induce increased biomass and chlorophyll, it also alters the Redfield ratio composition of these organisms. Coale et al. (2004) detail experiments carried out in the Southern Ocean in which the addition of iron to two differing nutrient zones led to altered Redfield ratios in the resultant phytoplankton blooms. In particular, a region of high and low silicic acid, termed the North Patch, produced organic matter with a 106C:14N:1P ratio. The reduction in phytoplankton’s nitrogen uptake in the North Patch is not yet fully understood. Do less nutrient enriched phytoplankton provide the same level of nourishment to the ocean’s primary consumers? Would zooplankton need to consume more to achieve their required levels of nitrogen intake? Additionally, a second fertilized patch, the South Patch, with both high nitrate and high silicic acid levels produced phytoplankton with a Redfield ratio of 99C:14N:1P. The drop in carbon associated with this fertilized patch is attributed to the highly silicic host waters. Iron fertilization in silicic waters favors planktonic blooms with a preponderance of diatoms. While the relatively reduced carbon uptake ratio would appear problematic for iron fertilization proponents, the relative increase in size and sinking potential of diatoms makes these concerns moot (Hicock and Millero, 2005).

ANOXIA The successful removal of atmospheric carbon may have detrimental effects on the oxygen content of both the surface and deep ocean. In the surface ocean, the side- effects of successful fertilization schemes have been unintentionally demonstrated in both lakes and at river deltas. The effect of agricultural runoff has been catastrophic

10 to local ecosystems. In particular, the of coastal Louisiana has been attributed to increased agribusiness fertilizer discharge transported to the Gulf of Mexico via the Mississippi River which in turn induces rampant productivity, ultimately leading to massive phytoplankton blooms. The subsequent death and decomposition of these blooms uses all available oxygen and results in anoxic surface waters, or dead zones. In the deep ocean, modeling studies indicate that enhanced surface water macronutrient drawdown and subsequent sinking could result in a net upward flux of O2. The migration of deep water O2 to intermediate and surface waters could induce deep water anoxia (Sarmiento and Orr, 1991). Anoxic conditions in both the surface and deep water have graver implications than simply being inhospitable to life. are prime for bacteria. The primary waste product of bacterial metabolism is methane, whose greenhouse warming potential is twenty-one times more powerful than carbon dioxide’s (IPCC, 2001). In response to these concerns Climos insists that their model of iron fertilization would not approach the scales requisite to induce significant far- reaching ocean water anoxia in either surface or deep ocean waters.

DOWNSTREAM EFFECTS When attempting to constrain the downstream effects of iron fertilization, two avenues must be examined: bloom dispersion and nutrient removal. Each process is subject to the chaotic motions of the sea, and each process may operate on conflicting timescales. Ocean currents are an inherently chaotic phenomenon, particularly on small spatial scales. Large scale ocean circulation is understood and predictable, but small scale transport remains elusive. Hugh Powell, of the Woods Hole Oceanographic Institution reports, “Depending on local currents, blooms can wind up strewn across the ocean like a ball of string or confined within swirling loops of water known as eddies (Figure 8). The eventual size of blooms from small iron additions can span 1,000 square kilometers or more, extend to depths of up to 100 meters, and drift hundreds of kilometers from their starting positions.” The process of dissolved nutrient removal from oceanic water masses has both short and long term consequences. In the immediate future, an effectively fertilized water mass will instigate productivity. Increased phytoplankton productivity will decrease water mass macronutrient (nitrogen, , and carbon) levels. The net effect of macronutrient depletion not only removes carbon, but other nutrients vital to organisms in the downstream food web. Essentially, the induced productivity in the upstream water mass may have no net effect on carbon removal; instead it may simply change its location. On a longer time scale, the deep water mass directly below the fertilized area will accrue the sinking detritus of increased productivity. This debris is composed of the biomass and waste products of both primary producers and their consumers. The decomposition of this deep water biomass leads to decreasing oxygen levels and increased nutrients. Eventually, the ocean’s natural circulation will bring these water masses back to the surface, where their low oxygen and high nutrient levels become favored sites of both methane and nitrous oxide creation by bacteria (W.H.O.I., 2008). Presently, no studies have delved into the long term effects of these re-circulating water masses.

11 NON-CO2 GREENHOUSE GASES While carbon dioxide has been attributed the preponderance of blame for its greenhouse warming effect, other atmospheric gases play a significant role in trapping radiative energy and warming the planet. With respect to iron fertilization, the biological production of greenhouse gases such as methane and nitrous oxide is a chief concern due to their significantly larger greenhouse warming potential (CH4 = 21, N2O = 310). Bacterial methane production occurs in all areas in which decomposition is active, but is prevalent in areas of low oxygen concentrations. (Scenarios in which ideal methane production conditions could be met through iron fertilization have already been discussed in the Downstream Effects and Anoxia sections.) Nitrous oxide in ocean waters is produced largely as a metabolic waste product of the primary consumers, zooplankton. As planktonic productivity rates increase due to iron fertilization, it is likely that the surge in the base of the food web will invigorate higher organisms such as zooplankton. Likewise, increased populations of metabolizing zooplankton will likely lead to higher levels of nitrous oxide emissions (W.H.O.I., 2008). At the basic level, these simple relationships are understood, but a quantitative understanding of emission and production rates remains problematic with respect to selling carbon offsets. Without concrete knowledge of biological methane and nitrous oxide release on both short and long-term time scales, little can be said about the net effectiveness of greenhouse warming mitigation induced by carbon sequestration. Climos addresses the dearth of knowledge of biologically produced methane and nitrous oxide with the following assumption: “In general, it seems safe to assume that the net of phytoplankton production or most major photosynthetic processes is beneficial from a warming perspective. This assumption will be tested by measurements before, during and after the initial demonstration. Climos will only sell the net offsets calculated after the impact of any warming gases produced is considered.”

DIMETHYLSULFIDE Dimethylsulfide (DMS) is a byproduct of the photosynthetic actions of the oceans’ primary producers. Its release and subsequent breakdown in the atmosphere produces cloud condensation nuclei (CCN). Increases in CCN promote cloud cover and strengthen the reflective capacity () of solar radiation, thereby decreasing ambient temperatures (Figure 9). Currently, a debate is raging as to the effect of global warming on the production of photosynthetic DMS (Charlson et al. 1987; Lovelock, 2007). This debate, termed CLAW vs. anti-CLAW (name derived from first letter of author’s last names) argues that increasing global temperatures will stratify the oceans, reduce nutrient rich waters, and ultimately lead to a decrease in ocean productivity, leading to increased warming as less DMS is released (Figure 10). Climos portends that their fertilization schemes are not of sufficient scale to alter planetary albedo levels, but also acknowledges the debate and uncertainties of this assumption.

BIODIVERSITY Previous studies have unquestionably demonstrated an increase in water column biomass in areas that have been fertilized with iron. Beyond anthropogenic fertilization, observations of melting Arctic icebergs and the subsequent release of their entrained has led Smith (2007) to conclude that not only did net phytoplankton

12 productivity increase, but beneficial effects on higher trophic levels were evident in the several kilometers surrounding the melting ice. A more detailed analysis of the spike in biomass by iron fertilization has been shown to severely alter the populations of various food webs. De Baar et al. (2005) demonstrate that the addition of iron to the water column lead to the sudden flourishing of a largely rare taxa. In general, their observations indicate that larger species tend to benefit more from iron introduction (Figure 11). By and large, ecosystem studies beyond the realm of primary producers and to a greater extent, primary consumers, remain in their infancy. Climos recognizes there will be ecological consequences, but suggests they have “good reason to believe that these will be largely positive.” Their justification for such a statement is derived from oceanic sediment drill cores and their associative fossil assemblages. This line of evidence tracks gradual ecosystem transitions as climate moves from periods of glacial to interglacial regimes. Problems with this statement arise when the time scale of glacial iron rich dust deposition is compared to anthropogenic fertilizations schemes. What the natural system accomplished over several millennia, Climos intends to achieve in decades. Logistical Concerns Should commercial iron fertilization schemes prove scientifically viable, there remains significant logistical challenges for their successful implementation. Three regions of the world’s oceans have been proposed as iron fertilization target areas and each presents its own difficulties. The Equatorial Pacific, receives year round insolation, has relatively calm waters, and is typically pleasantly warm, yet macronutrient stocks in this region tend to be low relative to high latitude waters and warmer conditions are more susceptible to bacterial blooms and subsequent anoxia (Boyd et al., 2000). The Pacific Northwest, while geographically less remote, has perhaps the second worst sailing conditions throughout the world’s seas, receives limited insolation in the Northern Hemisphere winter, and has lower macronutrient stocks than the Southern Ocean. The Southern Ocean, it is thought, holds the greatest potential for iron fertilization projects, but it is also home to the ‘raging forties’ and ‘furious fifties’, winds which are the result of the longest unimpeded fetch on the planet. The resultant seas and sail-ability are highly degraded. Additionally, its high latitude location is insolation limited during the Southern Hemisphere winter and generally speaking, it is geographically remote. One solution to many of these concerns, posited by a now defunct anthropogenic iron fertilization firm, Planktos, was the incorporation of iron seeding storage tanks on commercial ships (Zeebe and Archer, 2005). Ideally, commercial ships would distribute loads of dissolved iron while underway. Practically though, it was determined that commercial ships could not carry adequate dissolved iron supplies, rarely sail through HNLC waters, and typically avoid the potentially high carbon sequestration waters of the Southern Ocean due to the harsh sailing conditions.

RECOMMENDATION AND CONCLUSIONS

13 Ultimately, for commercial iron fertilization schemes to be successful, both the international scientific community and the corporate sector must develop quantitative predictions and produce in situ experimental results which both verify conclusive long- term atmospheric intra-sediment carbon sequestration and demonstrate a lack of adverse ecological impacts. To achieve that end, we recommend the following:

1) The largest uncertainty of anthropogenic iron fertilization schemes remains the lack of conclusive evidence that the sinking carbon-rich detritus of fertilized planktonic blooms actually reaches the sea-floor. Current sediment traps technologies are fraught with uncertainties and may overestimate export rates by a factor of 100. Future sediment trap technologies must reduce this error and begin to refine quantitative measurements of sediment sequestration.

2) The ocean-atmosphere-biogeochemical system is replete with complexity. While direct observations of these systems are ideal, they are often difficult to achieve over large spatial and long temporal scales. With this difficulty in mind, comprehensive coupled ocean-atmosphere-biogeochemical models need to be developed and refined, such that, long term large scale studies of both carbon sequestration and ecological consequences can be simulated.

3) Multiple, long term, large scale, publicly funded research demonstrations which aim to quantify the scientific unknowns and which seek to examine the long term ecological consequences across all trophic levels. Public funding for these demonstrations and their published results is necessary for scientific credibility. Experiments and studies delving into this subject matter conducted by corporations which seek to gain monetary profit could be deemed suspect.

Successful commercial iron fertilization hinges on predictable carbon export. A number of stochastic factors contribute to uncertainties in carbon export, sequestration, and residence time. Chief among them are variations in ocean chemistry, circulation, and initial trophic assemblage. To date, the most reliable experiments conducted in the most promising HNLC areas have failed to demonstrate the potential to have a substantial influence on the global carbon flux. In theory, commercial iron fertilization could have significant economic and carbon-mitigation potential, but significant quantitative and ecological analyses remain to be done before private companies are allowed to use iron fertilization to generate carbon credits for sale on the public market.

14 APPENDIX

Figures

Figure 1: Conceptual schematic of the biological pump which demonstrates the carbon flux balance between atmosphere, ocean, and land surface reservoirs.

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Figure 2: Global oceanic and terrestrial estimated primary production from September 1997 to August 2000. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center and ORBIMAGE. (http://oceancolor.gsfc.nasa.gov/SeaWiFS/BACKGROUND/Gallery/index.html#p17)

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Figure 3: European Project for Ice Coring in Antarctica (EPICA) dust data comparison with other climatic indicators. a, Stable isotope (δD) temperature analysis of EPICA Dome C (blue). b, Vostock dust flux (green). c, EDC dust flux (red). d, EDC dust size data (orange). e, Global ice volume (δ18O, green). f, Chinese loess magnetic track record (violet). (Lambert et al., 2008)

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Figure 4: Ocean iron fertilization probability curve of tons of carbon sequestered per ton of iron added. Redrawn with modifications scenarios added from Kite-Powell, (2007). Scenarios A, B, and C refer to Figure 5.

Figure 5: Profit scenarios (see Figure 4) for sales of carbon offsets generated by ocean iron fertilization.

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Figure 6: Gross profit calculations based on the sequestration potential of one ton of Fe. Calculations are based on the C sequestered/Fe added probability function in Figure 4.

Figure 7: Map of Southern Ocean showing areas of low, moderate, and high concentrations of silicic acid, as well as previous experiment locations. Although the experiment sites of SOIREE and EisenEx were in areas of moderate silicic acid concentrations, where Fe-fertilization should stimulate increased diatom growth, experiments did not result in a significant export of carbon (Hiscock and Millero, 2005).

19 Table 1: Open ocean organic C flux and cumulative regeneration throughout the water column (Martin et al., 1987). Depth (m) Organic C flux (Gt y­1) Cumulative % regeneration

100 5.9 0

150 4.2 30

200 3.3 45

300 2.3 62

400 1.8 70

500 1.5 75

600 1.3 78

800 1.0 83

1000 0.83 86

1500 0.59 90

2000 0.46 92

3000 0.32 95

4000 0.25 96

5000 0.21 96

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Table 2: (Boyd et al., 2007). Summarized results from the 12 Fe-fertilization experiments, which took place between 1993-2005, listed chronologically from left to right. Terms include mixed layer depth (MLD), dissolved inorganic carbon (DIC), dimethylsulfide (DMS), and no change (nc).

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Figure 8: SOFEX experimental fertilization patches as seen from space. North patch is day 28, south patch is day 20. Note the disparate chlorophyll distribution patterns due to mesoscale currents and local eddies (Coale et al., 2004).

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Figure 9: The CLAW hypothesis loop (Charlson et al., 1987).

Figure 10: The Anti-CLAW hypothesis loop (Lovelock, 2007).

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Figure 11: Phytoplankton community size structure in both a control and iron fertilized environment. Carbon estimates are based on analyses of picophytoplankton (PRO, SYN, PEUK), prymnesiophytes (PRYM), phaeocystis (PHAEO), diatoms (DIAT), and (DINO). The growth rates (m) of all taxa increase in response to added Fe,but most size categories are maintained at constant levels by corresponding increases in microzooplankton grazing (g), except for >20 mm diatoms (De Baar et al., 2005).

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