Ocean fertilization

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A visualization of bloom populations in the North Atlantic and North Pacific oceans from March 2003 to October 2006. The blue areas are nutrient deficient. Green to yellow show blooms fed by dust blown from nearby landmasses.[1]

Ocean fertilization or ocean nourishment is a type of climate engineering based on the purposeful introduction of nutrients to the upper ocean[2] to increase marine food production[3] and to remove carbon dioxide from the atmosphere. A number of techniques, including fertilization by iron, urea and phosphorus have been proposed.

History[edit]

EisenEx[edit]

In 2000 and 2004, comparable amounts of iron sulfate were discharged from the EisenEx. 10 to 20 percent of the algal bloom died off and sank to the sea floor.

LOHAFEX[edit]

LOHAFEX was an experiment initiated by the German Federal Ministry of Research and carried out by the German Alfred Wegener Institute (AWI) 2009 to study fertilization in the South Atlantic. India was also involved.[4]

As part of the experiment, the German research vessel Polarstern deposited 6 tons of ferrous sulfate in an area of 300 square kilometers. It was expected that the iron sulphate would distribute through the upper 15 metres (49 ft) of water and trigger an algal bloom. A significant part of the carbon dioxide dissolved in sea water would then be bound by the emerging bloom and sink to the ocean floor.

The ship left Cape Town, South Africa 7 January 2009. The expedition ended after 70 days on 17 March 2009 in Punta Arenas, Chile.

The Federal Environment Ministry called for the experiment to halt., partly because environmentalists predicted damage to marine plants. Others predicted long-term effects that would not be detectable during short-term observation[5] or that this would encourage large-scale ecosystem manipulation.[6][7]

Haida Gwaii project[edit]

In July 2012, the Haida Salmon Restoration Corporation dispersed 100 short tons (91 t) of iron sulphate dust into the Pacific Ocean several hundred miles west of the islands of Haida Gwaii. The Old Massett Village Council financed this project as a salmon enhancement project with $2.5 million in village funds.[8] The concept was that the formerly iron-deficient waters would produce more phytoplankton that would in turn serve as a "pasture" to feed salmon. Then-CEO Russ George hoped to sell carbon offsets to recover the costs. The project was plagued by charges of unscientific procedures and recklessness. George contended that 100 tons of iron is negligible compared to what naturally enters the ocean.[9]

Some environmentalists called the dumping a "blatant violation" of two international moratoria.[8][10] George said that the Old Massett Village Council and its lawyers approved the effort and at least seven Canadian agencies were aware of it.[9]

The 2013 salmon runs defied all expectations, more than quadrupling, from 50 million to 226 million fish.[11]

On 15 July 2014, the data gathered during the project were made publicly available under the ODbL license.[12]

Motivation[edit]

CO
2
sequestration in the ocean

The marine food chain is based on photosynthesis by marine phytoplankton that combine carbon with inorganic nutrients to produce organic matter. Production is limited by the availability of nutrients, most commonly nitrogen or iron. Numerous experiments[13] have demonstrated how iron fertilization can increase phytoplankton productivity. Nitrogen is a limiting nutrient over much of the ocean and can be supplied from various sources, including fixation by cyanobacteria. Carbon-to-iron ratios in phytoplankton are much larger than carbon-to-nitrogen or carbon-to-phosphorus ratios, so iron has the highest potential for sequestration per unit mass added.

Fertilization offers the prospect of both reducing the concentration of atmospheric greenhouse gases with the aim of avoiding dangerous climate change and at the same time increasing fish stocks via increasing primary production.

Fertilization may allow production of low cost protein in sufficient quantity to supply the needs of the increasing global population.[citation needed] While manipulation of the land ecosystem in support of agriculture for the benefit of humans has long been accepted, directly enhancing ocean productivity has not.

Approaches[edit]

Iron fertilization[edit]

Main article: Iron fertilization

Large areas of the oceans host few phytoplankton, despite high levels of nutrients. John Martin, director of the Moss Landing Marine Laboratories, hypothesized that the low levels of phytoplankton in these regions are due to a lack of iron. To test this hypothesis (known as the Iron Hypothesis) he arranged an experiment using samples of clean water from Antarctica. Iron was added to some of these samples. After several days the phytoplankton in the samples with added iron grew much more than in the untreated samples. This led Martin to speculate that increased iron concentrations in the oceans could partly explain past ice ages.[14] This experiment was followed by a larger field experiment (IRONEX I) where 445 kg of iron was added to a patch of ocean near the Galápagos Islands. The levels of phytoplankton increased three times in the area where iron had been added.[15] The success of this experiment and others led to proposals to use this technique to remove carbon dioxide from the atmosphere.[16]

Sperm whales act as agents of iron fertilisation when they transport iron from the deep ocean to the surface during prey consumption and defecation. Sperm whales have been shown to increase the levels of primary production and carbon export to the deep ocean by depositing iron rich faeces into surface waters of the Southern Ocean. The iron rich faeces causes phytoplankton to grow and take up more carbon from the atmosphere. When the phytoplankton dies, it sinks to the deep ocean and takes the atmospheric carbon with it. By reducing the abundance of sperm whales in the Southern Ocean, whaling resulted in an extra 2 million tonnes of carbon remaining in the atmosphere each year.[17]

Cost[edit]

The cost of distributing iron over large area of ocean is large compared with the value of the expected carbon credits.[18]

Phosphorus fertilization[edit]

Where phosphate is the limiting nutrient in the photic zone, addition of phosphate is expected to increase primary production. This technique can give 0.83W/m2 of globally averaged negative forcing,[19] which is sufficient to reverse the warming effect of about half the current levels of anthropogenic CO
2
emissions. It is notable, however, that CO
2
levels will have risen by the time this could be achieved.

Nitrogen fertilization[edit]

This technique (proposed by Ian Jones) proposes to fertilize the ocean with urea, a nitrogen rich substance, to encourage phytoplankton growth.[20] This has also been considered by Karl.[21] Concentrations of macronutrients per area of ocean surface would be similar to large natural upwellings. Once exported from the surface, the carbon remains sequestered for a long time.[22]

An Australian company, Ocean Nourishment Corporation (ONC), planned to inject hundreds of tonnes of urea into the ocean, in order to boost the growth of CO
2
-absorbing phytoplankton, as a way to combat climate change. In 2007, Sydney-based ONC completed an experiment involving one tonne of nitrogen in the Sulu Sea off the Philippines.[23]

Macronutrient nourishment can give 0.38W/m2 of globally averaged negative forcing,[19] which is sufficient to reverse the warming effect of current levels of around a quarter of anthropogenic CO
2
emissions.

The Ocean Nourishment Corporation claimed, “One Ocean Nourishment plant will remove approximately 5-8 million tonnes of CO2 from the atmosphere for each year of operation, equivalent to offsetting annual emissions from a typical 1200 MW coal-fired power station or the short-term sequestration from one million hectares of new growth forest”.[24]

The two dominant costs are manufacturing the nitrogen and nutrient delivery.[25]

Disadvantages[edit]

Efficiency[edit]

Algal cell chemical composition is 106 carbon: 16 nitrogen: 1 phosphorus: 0.0001 iron atoms. In other words, each atom of iron captures 1,060,000 atoms of carbon, while one nitrogen atom captures only 6.[26] Experimental iron fertilisation in HNLC regions have been supplied with excess iron which cannot be utilized before it is scavenged. Thus the organic material produced was much less than if the ratio of nutrients above were achieved. Only a fraction of the available nitrogen (because of iron scavenging) is drawn down. In culture bottle studies of oligotrophic water, adding nitrogen and phosphorus, can draw down considerably more nitrogen per dosing. The export production is only a small percentage of the new primary production and in the case of iron fertilization, iron scavenging means that regenerative production is small. With macronutrient fertilisation, regenerative production is expected to be large and supportive of larger total export. A paper by Lawrence[27] examines the various losses that reduce efficiency.

Impact on fisheries[edit]

Adding urea to the ocean can cause phytoplankton blooms that serve as a food source for zooplankton and in turn feed for fish. This may increase fish catches.[28] However, if cyanobacteria and dinoflagellates dominate phytoplankton assemblages that are considered poor quality food for fish then the increase in fish quantity may not be large.[29] Some evidence links iron fertilization from volcanic eruptions to increased fisheries production.[30][31]

Biodiversity[edit]

Many locations, such as the Tubbataha Reef in the Sulu Sea, support high marine biodiversity.[32] Nitrogen loading in coral reef areas can lead to community shifts towards algal overgrowth of corals and ecosystem disruption.[33] Fertilizing upstream of sensitive areas of ocean must be avoided.

Volcanic ash[edit]

Volcanic ash adds nutrients to the surface ocean. This is most apparent in nutrient-limited areas. Research on the effects of anthropogenic and eolian iron addition to the ocean surface suggests that nutrient-limited areas benefit most from a combination of nutrients provided by anthropogenic, eolian and volcanic deposition.[34] Some oceanic areas are limited in more than one nutrient, so fertilization regimes that includes all limited nutrients is more likely to succeed. Volcanic ash supplies multiple nutrients to the system, but excess metal ions can be harmful. The positive impacts of volcanic ash deposition are potentially outweighed by their potential to do harm.[citation needed]

Clear evidence documents that ash can be as much as 45 percent by weight in some deep marine sediments.[35][36] In the Pacific Ocean estimates claim that (on a millennial-scale) the atmospheric deposition of air-fall volcanic ash was as high as the deposition of desert dust.[37] This indicates the potential of volcanic ash as a significant iron source.

In August 2008 the Kasatochi volcanic eruption in the Aleutian Islands, Alaska, deposited ash in the nutrient-limited northeast Pacific. This ash (including iron) resulted in one of the largest phytoplankton blooms observed in the subarctic.[31][38] Fisheries scientists in Canada linked increased oceanic productivity from the volcanic iron to subsequent record returns of salmon in the Fraser River two years later [30]

International Law[edit]

International law presents some dilemmas around ocean fertilization. The United Nations Framework Convention on Climate Change (UNFCCC 1992) has accepted mitigation actions.[citation needed] However, the UNFCCC and its revisions recognise only forestation and reforestation projects as carbon sinks.[citation needed] Commercial companies such as Climos and GreenSea Ventures and the Australian-based Ocean Nourishment Corporation, planned to engage in fertilization projects. These companies invited green co-sponsors to finance their activities in return for provision of carbon credits to offset investors’ CO2 emissions.[39]

In June 2007 the London Dumping Convention issued a statement of concern noting 'the potential for large scale ocean iron fertilization to have negative impacts on the marine environment and human health',.[40] but did not defined 'large scale'. It is believed that the definition would include operations on the scale then planned by Planktos.[citation needed] Planktos was a US company that abandoned its plans to conduct 6 iron fertilzation cruises from 2007 to 2009, each of which would have dissolved up to 100 tons of iron over a 10,000 km2 area of ocean. Their ship Weatherbird II was refused entry to the port of Las Palmas in the Canary Islands where it was to take on provisions and scientific equipment.[41]

In 2008, the London Convention/London Protocol noted in resolution LC-LP.1 that knowledge on the effectiveness and potential environmental impacts of ocean fertilization was insufficient to justify activities other than research. This non-binding resolution stated that fertilization, other than research, "should be considered as contrary to the aims of the Convention and Protocol and do not currently qualify for any exemption from the definition of dumping".[42]

Working Group III of the United Nations Intergovernmental Panel on Climate Change examined ocean fertilization methods in its fourth assessment report and noted that the field-study estimates of the amount of carbon removed per ton of iron was probably over-estimated and that potential adverse effects have not yet been fully studied.[43]

Law of the sea[edit]

According to United Nations Convention on the Law of the Sea (LOSC 1982), all states are obliged to take all measures necessary to prevent, reduce and control pollution of the marine environment, to prohibit the transfer of damage or hazards from one area to another and to prohibit the transformation of one type pollution to another. How this relates to fertilization is undetermined.[44]

Solar radiation management[edit]

Fertilization may create sulfate aerosols that reflect sunlight, modifing the Earth's albedo, creating a cooling effect that reduces some of the effects of climate change. Enhancing the natural sulfur cycle in the Southern Ocean[45] by fertilizing with iron in order to enhance dimethyl sulfide production and cloud reflectivity may achieve this.[46][47]

See also[edit]

References[edit]

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  3. ^ Jones, I.S.F. & Young, H.E. (1997). "Engineering a large sustainable world fishery". Environmental Conservation. 24 (2): 99–104. doi:10.1017/S0376892997000167. 
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  45. ^ Wingenter, Oliver W.; Elliot, Scott M.; Blake, Donald R. (November 2007). "New Directions: Enhancing the natural sulfur cycle to slow global warming". Atmospheric Environment. 41 (34): 7373–5. doi:10.1016/j.atmosenv.2007.07.021. 
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  47. ^ Coale, K. H.; Johnson, K. S.; Buesseler, K.; Sofex Group. "SOFeX: Southern Ocean Iron Experiments. Overview and Experimental Design". American Geophysical Union. Fall. Meeting 2002. Bibcode:2002AGUFMOS22D..01C. 2002AGUFMOS22D..01C.