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135-488: Ocean iron fertilization is an example of a geoengineering technique. Iron fertilization attempts to encourage phytoplankton growth , which removes carbon from the atmosphere for at least a period of time. This technique is controversial because there is limited understanding of its complete effects on the marine ecosystem , including side effects and possibly large deviations from expected behavior. Such effects potentially include release of nitrogen oxides , and disruption of

270-556: A cell wall , as found in plants and many algae . Although the traditional practice of grouping protozoa with animals is no longer considered valid, the term continues to be used in a loose way to identify single-celled organisms that can move independently and feed by heterotrophy . Marine protozoans include zooflagellates , foraminiferans , radiolarians and some dinoflagellates . Radiolarians are unicellular predatory protists encased in elaborate globular shells usually made of silica and pierced with holes. Their name comes from

405-465: A 2013 study indicates the cost versus benefits of iron fertilization puts it behind carbon capture and storage and carbon taxes. While ocean iron fertilization could represent a potent means to slow global warming, there is a current debate surrounding the efficacy of this strategy and the potential adverse effects of this. The precautionary principle is a proposed guideline regarding environmental conservation. According to an article published in 2021,

540-668: A central role in determining the magnitude of ectothermic temperature-size responses, but it is hard to disentangle the relative effects of oxygen and temperature from field data because these two variables are often strongly inter-related in the surface ocean. Zooplankton can be broken down into size classes which are diverse in their morphology, diet, feeding strategies, etc. both within classes and between classes: Microzooplankton are defined as heterotrophic and mixotrophic plankton. They primarily consist of phagotrophic protists , including ciliates, dinoflagellates, and mesozooplankton nauplii . Microzooplankton are major grazers of

675-465: A climate engineering technology. The media tends to also use climate engineering for other technologies such as glacier stabilization, ocean liming, and iron fertilization of oceans. The latter would modify carbon sequestration processes that take place in oceans. Some types of climate engineering are highly controversial due to the large uncertainties around effectiveness, side effects and unforeseen consequences . Interventions at large scale run

810-643: A critical role in supporting the ocean's biological pump through various forms of carbon export , including the production of fecal pellets, mucous feeding webs, molts, and carcasses. Fecal pellets are estimated to be a large contributor to this export, with copepod size rather than abundance expected to determine how much carbon actually reaches the ocean floor. The importance of fecal pellets can vary both by time and location. For example, zooplankton bloom events can produce larger quantities of fecal pellets, resulting in greater measures of carbon export. Additionally, as fecal pellets sink, they are reworked by microbes in

945-885: A focused effort be placed on the development of instrumentation that can link changes in phytoplankton biomass or optical properties with grazing. Grazing is a central, rate-setting process in ocean ecosystems and a driver of marine biogeochemical cycling . In all ocean ecosystems, grazing by heterotrophic protists constitutes the single largest loss factor of marine primary production and alters particle size distributions. Grazing affects all pathways of export production, rendering grazing important both for surface and deep carbon processes. Predicting central paradigms of ocean ecosystem function, including responses to environmental change requires accurate representation of grazing in global biogeochemical, ecosystem and cross-biome-comparison models. Several large-scale analyses have concluded that phytoplankton losses, which are dominated by grazing are

1080-617: A gel matrix, which can increase massively in size during blooms . As a result, Phaeocystis is an important contributor to the marine carbon and sulfur cycles . A number of forams are mixotrophic. These have unicellular algae as endosymbionts , from diverse lineages such as the green algae , red algae , golden algae , diatoms , and dinoflagellates . Mixotrophic foraminifers are particularly common in nutrient-poor oceanic waters. Some forams are kleptoplastic , retaining chloroplasts from ingested algae to conduct photosynthesis . By trophic orientation, dinoflagellates are all over

1215-729: A geographical region, so are zooplankton. However, species of zooplankton are not dispersed uniformly or randomly within a region of the ocean. As with phytoplankton, 'patches' of zooplankton species exist throughout the ocean. Though few physical barriers exist above the mesopelagic , specific species of zooplankton are strictly restricted by salinity and temperature gradients, while other species can withstand wide temperature and salinity gradients. Zooplankton patchiness can also be influenced by biological factors, as well as other physical factors. Biological factors include breeding, predation, concentration of phytoplankton, and vertical migration. The physical factor that influences zooplankton distribution

1350-459: A global scale. Ocean fertilization occurs naturally when upwellings bring nutrient-rich water to the surface, as occurs when ocean currents meet an ocean bank or a sea mount . This form of fertilization produces the world's largest marine habitats . Fertilization can also occur when weather carries wind blown dust long distances over the ocean, or iron-rich minerals are carried into the ocean by glaciers , rivers and icebergs. About 70% of

1485-466: A greater risk of unintended disruptions of natural systems, resulting in a dilemma that such disruptions might be more damaging than the climate damage that they offset. However, the risks of such interventions must be seen in the context of the trajectory of climate change without them. The Union of Concerned Scientists warns that solar radiation modification could become an excuse to slow reductions in fossil fuel emissions and stall progress toward

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1620-506: A lack of iron. In 1989 he tested this hypothesis (known as the Iron Hypothesis ) by 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 iron fertilization 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. This experiment

1755-612: A lot about past environments and climates. Dinoflagellates are a phylum of unicellular flagellates with about 2,000 marine species. Some dinoflagellates are predatory , and thus belong to the zooplankton community. Their name comes from the Greek "dinos" meaning whirling and the Latin "flagellum" meaning a whip or lash . This refers to the two whip-like attachments (flagella) used for forward movement. Most dinoflagellates are protected with red-brown, cellulose armour. Excavates may be

1890-528: A low-carbon economy, as the technology does not address these root causes of climate change. Climate engineering (or geoengineering) has been used as an umbrella term for both carbon dioxide removal and solar radiation management , when applied at a planetary scale. However, these two methods have very different geophysical characteristics, which is why the Intergovernmental Panel on Climate Change no longer uses this term. This decision

2025-417: A low-carbon economy. However, several public opinion surveys and focus groups reported either a desire to increase emission cuts in the presence of climate engineering, or no effect. Other modelling work suggests that the prospect of climate engineering may in fact increase the likelihood of emissions reduction. If climate engineering can alter the climate, then this raises questions whether humans have

2160-441: A major component of the carbon-rich deep sea precipitation known as marine snow . Marine snow also includes fish fecal pellets and other organic detritus, and steadily falls thousands of meters below active plankton blooms. Of the carbon-rich biomass generated by plankton blooms, half (or more) is generally consumed by grazing organisms ( zooplankton , krill , small fish, etc.) but 20 to 30% sinks below 200 meters (660 ft) into

2295-507: A mass basis, each kilogram of iron can fix 83,000 kg of carbon dioxide. The 2004 EIFEX experiment reported a carbon dioxide to iron export ratio of nearly 3000 to 1. The atomic ratio would be approximately: "3000 C: 58,000 N: 3,600 P: 1 Fe". Therefore, small amounts of iron (measured by mass parts per trillion) in HNLC zones can trigger large phytoplankton blooms on the order of 100,000 kilograms of plankton per kilogram of iron. The size of

2430-475: A minor effect on mitigating CO2-induced acidification at the surface ocean." Unfortunately, the impact on ocean acidification would likely not change due to the low effects that iron fertilization has on CO 2 levels. Consideration of iron's importance to phytoplankton growth and photosynthesis dates to the 1930s when Dr Thomas John Hart , a British marine biologist based on the RRS ; Discovery II in

2565-541: A mix of internal plastids and external sources. Many marine microzooplankton are mixotrophic, which means they could also be classified as phytoplankton. Zooplankton ( / ˈ z oʊ . ə p l æ ŋ k t ən / ; / ˌ z oʊ . ə ˈ p l æ ŋ k t ən / ) are heterotrophic (sometimes detritivorous ) plankton . The word zooplankton is derived from Ancient Greek : ζῷον , romanized :  zôion , lit.   'animal'; and πλᾰγκτός , planktós , 'wanderer; drifter'. Zooplankton

2700-426: A planetary scale. However, these two processes have very different characteristics, and are now often discussed separately. Carbon dioxide removal techniques remove carbon dioxide from the atmosphere, and are part of climate change mitigation . Solar radiation modification is the reflection of some sunlight (solar radiation) back to space to cool the earth. Some publications include passive radiative cooling as

2835-480: A range of approaches to limit global warming by increasing the amount of sunlight ( solar radiation ) that the atmosphere reflects back to space or by reducing the trapping of outgoing thermal radiation . Among the multiple potential approaches, stratospheric aerosol injection is the most-studied, followed by marine cloud brightening . SRM could be a temporary measure to limit climate-change impacts while greenhouse gas emissions are reduced and carbon dioxide

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2970-409: A result, zooplankton are primarily found in surface waters where food resources (phytoplankton or other zooplankton) are abundant. Zooplankton can also act as a disease reservoir . Crustacean zooplankton have been found to house the bacterium Vibrio cholerae , which causes cholera , by allowing the cholera vibrios to attach to their chitinous exoskeletons . This symbiotic relationship enhances

3105-905: A result, zooplankton must acquire nutrients by feeding on other organisms such as phytoplankton, which are generally smaller than zooplankton. Most zooplankton are microscopic but some (such as jellyfish ) are macroscopic , meaning they can be seen with the naked eye . Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellates , foraminiferans , radiolarians , some dinoflagellates and marine microanimals . Macroscopic zooplankton include pelagic cnidarians , ctenophores , molluscs , arthropods and tunicates , as well as planktonic arrow worms and bristle worms . The distinction between autotrophy and heterotrophy often breaks down in very small organisms. Recent studies of marine microplankton have indicated over half of microscopic plankton are mixotrophs , which can obtain energy and carbon from

3240-563: A significant amount of carbon into the deep ocean, where it was expected to remain for centuries to millennia. The eddy was chosen because it offered a largely self-contained test system. As of day 24, nutrients, including nitrogen, phosphorus and silicic acid that diatoms use to construct their shells, declined. Dissolved inorganic carbon concentrations were reduced below equilibrium with atmospheric CO 2 . In surface water, particulate organic matter (algal remains) including silica and  chlorophyll increased. After day 24, however,

3375-440: A significant benefit to the marine food chain in addition to sequestering carbon for long periods of time. A 2009 study tested the potential of iron fertilization to reduce both atmospheric CO 2 and ocean acidity using a global ocean carbon model. The study found that, "Our simulations show that ocean iron fertilization, even in the extreme scenario by depleting global surface macronutrient concentration to zero at all time, has

3510-447: A significant role in supplying the world's oceans with iron. Volcanic ash is composed of glass shards, pyrogenic minerals, lithic particles and other forms of ash that release nutrients at different rates depending on structure and the type of reaction caused by contact with water. Increases of biogenic opal in the sediment record are associated with increased iron accumulation over the last million years. In August 2008, an eruption in

3645-415: A small amount of carbon. Ocean iron fertilization is an example of a geoengineering technique that involves intentional introduction of iron-rich deposits into oceans, and is aimed to enhance biological productivity of organisms in ocean waters in order to increase carbon dioxide ( CO 2 ) uptake from the atmosphere, possibly resulting in mitigating its global warming effects . Iron is a trace element in

3780-563: A surface complex with the Fe (III) metal center of an iron-containing mineral (such as hematite or goethite ). On exposure to solar radiation the complex is converted to an excited energy state in which the ligand, acting as bridge and an electron donor , supplies an electron to Fe(III) producing soluble Fe(II). Consistent with this, studies documented a distinct diel variation in the concentrations of Fe (II) and Fe(III) in which daytime Fe(II) concentrations exceed those of Fe(III). Volcanic ash has

3915-457: A test. They also acknowledged that this intervention cannot prevent sea level rise from the increased ocean heat content , and would be ineffective in the long run without greenhouse gas emission reductions. Interventions at large scale run a greater risk of unintended disruptions of natural systems, resulting in a dilemma that such disruptions might be more damaging than the climate damage that they offset. Climate engineering may reduce

4050-493: A turn over in the plankton masses that are produced. This results in no beneficial effects and actually causes an increase in CO 2 . Finally, a 2010 study showed that iron enrichment stimulates toxic diatom production in high-nitrate, low-chlorophyll areas which, the authors argue, raises "serious concerns over the net benefit and sustainability of large-scale iron fertilizations". Nitrogen released by cetaceans and iron chelate are

4185-402: A variety of measurements, combining ship-borne and remote sampling, submarine filtration traps, tracking buoy spectroscopy and satellite telemetry . Unpredictable ocean currents can remove experimental iron patches from the pelagic zone, invalidating the experiment. The potential of fertilization to tackle global warming is illustrated by the following figures. If phytoplankton converted all

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4320-408: A year, meaning they respond to climate changes between years. Sparse, monthly sampling will still indicate vacillations. Protozoans are protists that feed on organic matter such as other microorganisms or organic tissues and debris. Historically, the protozoa were regarded as "one-celled animals", because they often possess animal -like behaviours, such as motility and predation , and lack

4455-423: Is 0.29 W/m of globally averaged negative forcing, offsetting 1/6 of current levels of anthropogenic CO 2 emissions. These benefits have been called into question by research suggesting that fertilization with iron may deplete other essential nutrients in the seawater causing reduced phytoplankton growth elsewhere — in other words, that iron concentrations limit growth more locally than they do on

4590-600: Is a categorization spanning a range of organism sizes including small protozoans and large metazoans . It includes holoplanktonic organisms whose complete life cycle lies within the plankton, as well as meroplanktonic organisms that spend part of their lives in the plankton before graduating to either the nekton or a sessile , benthic existence. Although zooplankton are primarily transported by ambient water currents, many have locomotion , used to avoid predators (as in diel vertical migration ) or to increase prey encounter rate. Just as any species can be limited within

4725-402: Is a limiting nutrient in many ocean waters. They hoped that the iron would fertilize algae, which would bolster the bottom of the marine food chain and sequester carbon as uneaten algae died. The experiment was demolished by a storm, leaving inconclusive results. The maximum possible result from iron fertilization, assuming the most favourable conditions and disregarding practical considerations,

4860-527: Is also only 30% likely to work. Constructions blocking even 50% of the warm water flow are expected to be far more effective, yet far more difficult as well. Some researchers argued that this proposal could be ineffective, or even accelerate sea level rise. The authors of the original proposal suggested attempting this intervention on smaller sites, like the Jakobshavn Glacier in Greenland , as

4995-529: Is an important iron source. Satellite images and data (such as PODLER, MODIS, MSIR) combined with back-trajectory analyses identified natural sources of iron–containing dust. Iron-bearing dusts erode from soil and are transported by wind. Although most dust sources are situated in the Northern Hemisphere, the largest dust sources are located in northern and southern Africa, North America, central Asia and Australia. Heterogeneous chemical reactions in

5130-406: Is being exported via zooplankton fecal pellet production. Carcasses are also gaining recognition as being important contributors to carbon export. Jelly falls – the mass sinking of gelatinous zooplankton carcasses – occur across the world as a result of large blooms. Because of their large size, these gelatinous zooplankton are expected to hold a larger carbon content, making their sinking carcasses

5265-413: Is best considered as a potential complement to the mitigation of CO 2 emissions, rather than as an alternative to it". The IMechE report examined a small subset of proposed methods (air capture, urban albedo and algal-based CO 2 capture techniques), and its main conclusions in 2011 were that climate engineering should be researched and trialed at the small scale alongside a wider decarbonization of

5400-658: Is evidence from DNA analysis that dinoflagellate symbiosis with radiolarians evolved independently from other dinoflagellate symbioses, such as with foraminifera . A mixotroph is an organism that can use a mix of different sources of energy and carbon , instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. It is estimated that mixotrophs comprise more than half of all microscopic plankton. There are two types of eukaryotic mixotrophs: those with their own chloroplasts , and those with endosymbionts —and others that acquire them through kleptoplasty or by enslaving

5535-515: Is generally consumed by other organisms (small fish, zooplankton , etc.) and substantial part of rest of the deposits that sink beneath plankton blooms may be re-dissolved in the water and gets transferred to the surface where it eventually returns to the atmosphere, thus, nullifying any possible intended effects regarding carbon sequestration. Nevertheless, supporters of the idea of iron fertilization believe that carbon sequestration should be re-defined over much shorter time frames and claim that since

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5670-514: Is loss from zooplankton in the form of respired CO 2 . The relative sizes of zooplankton and prey also mediate how much carbon is released via sloppy feeding. Smaller prey are ingested whole, whereas larger prey may be fed on more “sloppily”, that is more biomatter is released through inefficient consumption. There is also evidence that diet composition can impact nutrient release, with carnivorous diets releasing more dissolved organic carbon (DOC) and ammonium than omnivorous diets. Zooplankton play

5805-586: Is more and more often integrated into climate policy , as an element of climate change mitigation strategies. Achieving net zero emissions will require first and foremost deep and sustained cuts in emissions, and then—in addition—the use of CDR ("CDR is what puts the net into net zero emissions" ). In the future, CDR may be able to counterbalance emissions that are technically difficult to eliminate, such as some agricultural and industrial emissions. Solar radiation modification (SRM), also known as solar radiation management, or solar geoengineering, refers to

5940-481: Is one of several in which iron fertilization could be conducted—the Galapagos islands area another potentially suitable location. Some species of plankton produce dimethyl sulfide (DMS), a portion of which enters the atmosphere where it is oxidized by hydroxyl radicals (OH), atomic chlorine (Cl) and bromine monoxide (BrO) to form sulfate particles, and potentially increase cloud cover. This may increase

6075-402: Is recycled back to the marine environment. Low feeding rates typically lead to high AE and small, dense pellets, while high feeding rates typically lead to low AE and larger pellets with more organic content. Another contributing factor to DOM release is respiration rate. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon

6210-576: Is relatively inexpensive compared to scrubbing , direct injection and other industrial approaches, and can theoretically sequester for less than €5/ton CO 2 , creating a substantial return. In August, 2010, Russia established a minimum price of €10/ton for offsets to reduce uncertainty for offset providers. Scientists have reported a 6–12% decline in global plankton production since 1980. A full-scale plankton restoration program could regenerate approximately 3–5 billion tons of sequestration capacity worth €50-100 billion in carbon offset value. However,

6345-456: Is released from zooplankton individuals or populations. Absorption efficiency (AE) is the proportion of food absorbed by plankton that determines how available the consumed organic materials are in meeting the required physiological demands. Depending on the feeding rate and prey composition, variations in AE may lead to variations in fecal pellet production, and thus regulates how much organic material

6480-465: Is removed , but would not be a substitute for reducing emissions. SRM is a form of climate engineering. Enhancing the solar reflectance and thermal emissivity of Earth in the atmospheric window through passive daytime radiative cooling has been proposed as an alternative or "third approach" to climate engineering that is "less intrusive" and more predictable or reversible than stratospheric aerosol injection. Ocean geoengineering involves modifying

6615-610: Is sensitive to changes in temperature due to the thermal dependence of physiological processes. The plankton is mainly composed of ectotherms which are organisms that do not generate sufficient metabolic heat to elevate their body temperature, so their metabolic processes depends on external temperature. Consequently, ectotherms grow more slowly and reach maturity at a larger body size in colder environments, which has long puzzled biologists because classic theories of life-history evolution predict smaller adult sizes in environments delaying growth. This pattern of body size variation, known as

6750-424: Is to reduce sea level rise by installing underwater "curtains" to protect Antarctic glaciers from warming waters, or by drilling holes in ice to pump out water and heat. Enriching seawater with calcium hydroxide ( lime ) has been reported to lower ocean acidity , which reduces pressure on marine life such as oysters and absorbs CO 2 . The added lime raised the water's pH , capturing CO 2 in

6885-621: The CO 2 uptake and that due to the ocean's albedo increase, however the amount of cooling by this particular effect is very uncertain. Beginning with the Kyoto Protocol , several countries and the European Union established carbon offset markets which trade certified emission reduction credits (CERs) and other types of carbon credit instruments. In 2007 CERs sold for approximately €15–20/ton CO 2 . Iron fertilization

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7020-533: The Namibian coast. Whilst this approach has been called ocean geoengineering by the researchers it is just another form of carbon dioxide removal via sequestration. Another term that is used to describe this process is blue carbon management and also marine geoengineering . Some engineering interventions have been proposed for Thwaites Glacier and the nearby Pine Island Glacier to physically stabilize its ice or to preserve it. These interventions would block

7155-666: The Portuguese Man o' War ; crustaceans such as cladocerans , copepods , ostracods , isopods , amphipods , mysids and krill ; chaetognaths (arrow worms); molluscs such as pteropods ; and chordates such as salps and juvenile fish. This wide phylogenetic range includes a similarly wide range in feeding behavior: filter feeding , predation and symbiosis with autotrophic phytoplankton as seen in corals. Zooplankton feed on bacterioplankton , phytoplankton, other zooplankton (sometimes cannibalistically ), detritus (or marine snow ) and even nektonic organisms . As

7290-604: The Sahara desert fertilizes the Atlantic Ocean and the Amazon rainforest . The naturally occurring iron oxide in atmospheric dust reacts with hydrogen chloride from sea spray to produce iron chloride, which degrades methane and other greenhouse gases, brightens clouds and eventually falls with the rain in low concentration across a wide area of the globe. Unlike ship based deployment, no trials have been performed of increasing

7425-520: The South Atlantic . India was also involved. 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 material 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

7560-607: The Southern Ocean speculated - in "On the phytoplankton of the South-West Atlantic and Bellingshausen Sea, 1929-31" - that great "desolate zones" (areas apparently rich in nutrients, but lacking in phytoplankton activity or other sea life) might be iron-deficient. Hart returned to this issue in a 1942 paper entitled "Phytoplankton periodicity in Antarctic surface waters", but little other scientific discussion

7695-399: The Southern Ocean , would enhance dimethyl sulfide production and consequently cloud reflectivity . This could potentially be used as regional SRM, to slow Antarctic ice from melting. Such techniques also tend to sequester carbon , but the enhancement of cloud albedo also appears to be a likely effect. Another 2022 experiment attempted to sequester carbon using giant kelp planted off

7830-533: The UNFCCC should make increased efforts towards mitigating and adapting to climate change, and in particular to agreeing to global emissions reductions", and that "[nothing] now known about geoengineering options gives any reason to diminish these efforts". Nonetheless, the report also recommended that "research and development of climate engineering options should be undertaken to investigate whether low-risk methods can be made available if it becomes necessary to reduce

7965-945: The US Congress , the US National Academy of Sciences, Engineering, and Medicine, the Royal Society , the UK Parliament , the Institution of Mechanical Engineers , and the Intergovernmental Panel on Climate Change . In 2009, the Royal Society in the UK reviewed a wide range of proposed climate engineering methods and evaluated them in terms of effectiveness, affordability, timeliness, and safety (assigning qualitative estimates in each assessment). The key recommendations reports were that "Parties to

8100-536: The albedo of the planet and so cause cooling—this proposed mechanism is central to the CLAW hypothesis . This is one of the examples used by James Lovelock to illustrate his Gaia hypothesis . During SOFeX, DMS concentrations increased by a factor of four inside the fertilized patch. Widescale iron fertilization of the Southern Ocean could lead to significant sulfur-triggered cooling in addition to that due to

8235-458: The food chain for other marine organisms . There are two ways of performing artificial iron fertilization: ship based direct into the ocean and atmospheric deployment. Trials of ocean fertilization using iron sulphate added directly to the surface water from ships are described in detail in the experiment section below. Iron-rich dust rising into the atmosphere is a primary source of ocean iron fertilization. For example, wind blown dust from

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8370-450: The latest IPCC assessment report in 2022 but are included under this umbrella term by other publications on this topic: Carbon dioxide removal (CDR) is a process in which carbon dioxide (CO 2 ) is removed from the atmosphere by deliberate human activities and durably stored in geological, terrestrial, or ocean reservoirs, or in products. This process is also known as carbon removal, greenhouse gas removal or negative emissions. CDR

8505-563: The marine food web , gelatinous organisms with a body plan largely based on water that offers little nutritional value or interest for other organisms apart from a few specialised predators such as the ocean sunfish and the leatherback sea turtle . That view has recently been challenged. Jellyfish, and more gelatinous zooplankton in general, which include salps and ctenophores , are very diverse, fragile with no hard parts, difficult to see and monitor, subject to rapid population swings and often live inconveniently far from shore or deep in

8640-457: The nitrate and phosphate present in the surface mixed layer across the entire Antarctic circumpolar current into organic carbon , the resulting carbon dioxide deficit could be compensated by uptake from the atmosphere amounting to about 0.8 to 1.4 gigatonnes of carbon per year. This quantity is comparable in magnitude to annual anthropogenic fossil fuels combustion of approximately 6 gigatonnes. The Antarctic circumpolar current region

8775-691: The ocean , or by currents in seas , lakes or rivers . Zooplankton can be contrasted with phytoplankton ( cyanobacteria and microalgae ), which are the plant-like component of the plankton community (the " phyto- " prefix comes from Ancient Greek: φῠτόν , romanized:  phutón , lit.   'plant', although taxonomically not plants ). Zooplankton are heterotrophic (other-feeding), whereas phytoplankton are autotrophic (self-feeding), often generating biological energy and macromolecules through chlorophyllic carbon fixation using sunlight — in other words, zooplankton cannot manufacture their own food, while phytoplankton can. As

8910-545: The oligotrophic waters of the open ocean. Through sloppy feeding, excretion, egestion, and leaching of fecal pellets , zooplankton release dissolved organic matter (DOM) which controls DOM cycling and supports the microbial loop . Absorption efficiency, respiration, and prey size all further complicate how zooplankton are able to transform and deliver carbon to the deep ocean . Excretion and sloppy feeding (the physical breakdown of food source) make up 80% and 20% of crustacean zooplankton-mediated DOM release respectively. In

9045-449: The precautionary principle (PP) is a concept that states, "The PP means that when it is scientifically plausible that human activities may lead to morally unacceptable harm, actions shall be taken to avoid or diminish that harm: uncertainty should not be an excuse to delay action." Based on this principle, and because there is little data quantifying the effects of iron fertilization, it is the responsibility of leaders in this field to avoid

9180-514: The 2012 iron fertilization; many factors contribute to predictive models, and most data from the experiment are considered to be of questionable scientific value. On 15 July 2014, the data gathered during the project were made publicly available under the ODbL license. In 2022, a UK/India research team plans to place iron-coated rice husks in the Arabian Sea , to test whether increasing time at

9315-714: The Aleutian Islands deposited ash in the nutrient-limited Northeast Pacific. This ash and iron deposition resulted in one of the largest phytoplankton blooms observed in the subarctic. Previous instances of biological carbon sequestration triggered major climatic changes, lowering the temperature of the planet, such as the Azolla event . Plankton that generate calcium or silicon carbonate skeletons, such as diatoms , coccolithophores and foraminifera , account for most direct sequestration. When these organisms die their carbonate skeletons sink relatively quickly and form

9450-698: 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' CO 2 emissions. LOHAFEX was an experiment initiated by the German Federal Ministry of Research and carried out by the German Alfred Wegener Institute (AWI) in 2009 to study fertilization in

9585-411: The Latin for "hole bearers". Their shells, often called tests , are chambered (forams add more chambers as they grow). The shells are usually made of calcite, but are sometimes made of agglutinated sediment particles or chiton , and (rarely) silica. Most forams are benthic, but about 40 species are planktic. They are widely researched with well-established fossil records which allow scientists to infer

9720-521: The Latin for "radius". They catch prey by extending parts of their body through the holes. As with the silica frustules of diatoms, radiolarian shells can sink to the ocean floor when radiolarians die and become preserved as part of the ocean sediment . These remains, as microfossils , provide valuable information about past oceanic conditions. Like radiolarians, foraminiferans ( forams for short) are single-celled predatory protists, also protected with shells that have holes in them. Their name comes from

9855-667: The United States, United Kingdom, Australia, and New Zealand. Public awareness of climate engineering was low; less than a fifth of respondents reported prior knowledge. Perceptions of the six climate engineering methods proposed (three from the carbon dioxide removal group and three from the solar radiation modification group) were largely negative and frequently associated with attributes like 'risky', 'artificial' and 'unknown effects'. Carbon dioxide removal methods were preferred over solar radiation modification. Public perceptions were remarkably stable with only minor differences between

9990-422: The action as a salmon enhancement project with $ 2.5 million in village funds. 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 accompanied by charges of unscientific procedures and recklessness. George contended that 100 tons

10125-420: The atmosphere modify the speciation of iron in dust and may affect the bioavailability of deposited iron. The soluble form of iron is much higher in aerosols than in soil (~0.5%). Several photo-chemical interactions with dissolved organic acids increase iron solubility in aerosols. Among these, photochemical reduction of oxalate -bound Fe(III) from iron-containing minerals is important. The organic ligand forms

10260-436: The bacterium's ability to survive in an aquatic environment, as the exoskeleton provides the bacterium with carbon and nitrogen. Body size has been defined as a "master trait" for plankton as it is a morphological characteristic shared by organisms across taxonomy that characterises the functions performed by organisms in ecosystems. It has a paramount effect on growth, reproduction, feeding strategies and mortality. One of

10395-494: The carbon is suspended in the deep ocean it is effectively isolated from the atmosphere for hundreds of years, and thus, carbon can be effectively sequestered. Assuming the ideal conditions, the upper estimates for possible effects of iron fertilization in slowing down global warming is about 0.3W/m of averaged negative forcing which can offset roughly 15–20% of the current anthropogenic CO 2 emissions. However, although this approach could be looked upon as an easy option to lower

10530-472: The ciliate abundance was mixotrophic, and up to 65% of the amoeboid, foram and radiolarian biomass was mixotrophic. Phaeocystis species are endosymbionts to acantharian radiolarians. Phaeocystis is an important algal genus found as part of the marine phytoplankton around the world. It has a polymorphic life cycle, ranging from free-living cells to large colonies. It has the ability to form floating colonies, where hundreds of cells are embedded in

10665-427: The colder water strata below the thermocline . Much of this fixed carbon continues into the abyss, but a substantial percentage is redissolved and remineralized. At this depth, however, this carbon is now suspended in deep currents and effectively isolated from the atmosphere for centuries. Evaluation of the biological effects and verification of the amount of carbon actually sequestered by any particular bloom involves

10800-492: The concentration of atmospheric carbon dioxide by altering rates of carbon sequestration. In fact, fertilization is an important process that occurs naturally in the ocean waters. For instance, upwellings of ocean currents can bring nutrient-rich sediments to the surface. Another example is through transfer of iron-rich minerals, dust, and volcanic ash over long distances by rivers, glaciers, or wind. Moreover, it has been suggested that whales can transfer iron-rich ocean dust to

10935-403: The concentration of CO 2 in the atmosphere, ocean iron fertilization is still quite controversial and highly debated due to possible negative consequences on marine ecosystems . Research on this area has suggested that fertilization through deposition of large quantities of iron-rich dust into the ocean floor can significantly disrupt the ocean's nutrient balance and cause major complications in

11070-493: The contribution of jellyfish to the energy budgets of predators may be much greater than assumed because of rapid digestion, low capture costs, availability, and selective feeding on the more energy-rich components. Feeding on jellyfish may make marine predators susceptible to ingestion of plastics." According to a 2017 study, narcomedusae consume the greatest diversity of mesopelagic prey, followed by physonect siphonophores , ctenophores and cephalopods . The importance of

11205-457: The cryptophytes by itself, and instead relies on ingesting ciliates such as the red Myrionecta rubra , which sequester their chloroplasts from a specific cryptophyte clade (Geminigera/Plagioselmis/Teleaulax)". Free-living species in the crustacean class Copepoda are typically 1 to 2 mm long with teardrop-shaped bodies. Like all crustaceans, their bodies are divided into three sections: head, thorax, and abdomen, with two pairs of antennae;

11340-495: The different countries in the surveys. Some environmental organizations (such as Friends of the Earth and Greenpeace ) have been reluctant to endorse or oppose solar radiation modification, but are often more supportive of nature-based carbon dioxide removal projects, such as afforestation and peatland restoration . Several organizations have investigated climate engineering with a view to evaluating its potential, including

11475-450: The dilution technique, an elegant method of measuring microzooplankton herbivory rate, has been developed for almost four decades (Landry and Hassett 1982). The number of observations of microzooplankton herbivory rate is around 1600 globally, far less than that of primary productivity (> 50,000). This makes validating and optimizing the grazing function of microzooplankton difficult in ocean ecosystem models. Mesozooplankton are one of

11610-483: The economy. In 2015, the US National Academy of Sciences, Engineering, and Medicine concluded a 21-month project to study the potential impacts, benefits, and costs of climate engineering. The differences between these two classes of climate engineering "led the committee to evaluate the two types of approaches separately in companion reports, a distinction it hopes carries over to future scientific and policy discussions." The resulting study titled Climate Intervention

11745-446: The emerging bloom and sink to the ocean floor. 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 or that this would encourage large-scale ecosystem manipulation. A 2012 study deposited iron fertilizer in an eddy near Antarctica. The resulting algal bloom sent

11880-547: The entire phototrophic cell. The distinction between plants and animals often breaks down in very small organisms. Possible combinations are photo- and chemotrophy , litho- and organotrophy , auto- and heterotrophy or other combinations of these. Mixotrophs can be either eukaryotic or prokaryotic . They can take advantage of different environmental conditions. Many marine microzooplankton are mixotrophic, which means they could also be classified as phytoplankton. Recent studies of marine microzooplankton found 30–45% of

12015-496: The first pair is often long and prominent. They have a tough exoskeleton made of calcium carbonate and usually have a single red eye in the centre of their transparent head. About 13,000 species of copepods are known, of which about 10,200 are marine. They are usually among the more dominant members of the zooplankton. In addition to copepods the crustacean classes ostracods , branchiopods and malacostracans also have planktonic members. Barnacles are planktonic only during

12150-502: The flow of warm ocean water, which currently renders the collapse of these two glaciers practically inevitable even without further warming. A proposal from 2018 included building sills at the Thwaites' grounding line to either physically reinforce it, or to block some fraction of warm water flow. The former would be the simplest intervention, yet equivalent to "the largest civil engineering projects that humanity has ever attempted". It

12285-649: The form of calcium bicarbonate or as carbonate deposited in mollusk shells. Lime is produced in volume for the cement industry. This was assessed in 2022 in an experiment in Apalachicola, Florida in an attempt to halt declining oyster populations. pH levels increased modestly, as CO 2 was reduced by 70 ppm. A 2014 experiment added sodium hydroxide (lye) to part of Australia's Great Barrier Reef . It raised pH levels to nearly preindustrial levels. However, producing alkaline materials typically releases large amounts of CO 2 , partially offsetting

12420-566: The harmful effects of this procedure. This school of thought is one argument against using iron fertilization on a wide scale, at least until more data is available to analyze the repercussions of this. Critics are concerned that fertilization will create harmful algal blooms (HAB) as many toxic algae are often favored when iron is deposited into the marine ecosystem. A 2010 study of iron fertilization in an oceanic high-nitrate, low-chlorophyll environment, however, found that fertilized Pseudo-nitzschia diatom spp., which are generally nontoxic in

12555-476: The iron particles is critical. Particles of 0.5–1 micrometer or less seem to be ideal both in terms of sink rate and bioavailability. Particles this small are easier for cyanobacteria and other phytoplankton to incorporate and the churning of surface waters keeps them in the euphotic or sunlit biologically active depths without sinking for long periods. One way to add small amounts of iron to HNLC zones would be Atmospheric Methane Removal . Atmospheric deposition

12690-452: The larger size classes of zooplankton. In most regions, mesozooplankton are dominated by copepods , such as Calanus finmarchicus and Calanus helgolandicus . Mesozooplankton are an important prey for fish. As plankton are rarely fished, it has been argued that mesoplankton abundance and species composition can be used to study marine ecosystems' response to climate change. This is because they have life cycles that generally last less than

12825-461: The larval stage. Ichthyoplankton are the eggs and larvae of fish ("ichthyo" comes from the Greek word for fish ). They are planktonic because they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juvenile fish . Fish larvae are part of

12960-418: The majority of organic carbon loss from marine primary production . However, zooplankton grazing remains one of the key unknowns in global predictive models of carbon flux, the marine food web structure and ecosystem characteristics, because empirical grazing measurements are sparse, resulting in poor parameterisation of grazing functions. To overcome this critical knowledge gap, it has been suggested that

13095-684: The marine sky in an effort to increase cloud "brightness" (reflective capacity). The sea salt is launched from the USS Hornet Sea, Air & Space Museum (based on the project's regulatory filings). Zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo- " prefix comes from Ancient Greek : ζῷον , romanized :  zôion , lit.   'animal'), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in

13230-413: The most basal flagellate lineage. Dinoflagellates often live in symbiosis with other organisms. Many nassellarian radiolarians house dinoflagellate symbionts within their tests. The nassellarian provides ammonium and carbon dioxide for the dinoflagellate, while the dinoflagellate provides the nassellarian with a mucous membrane useful for hunting and protection against harmful invaders. There

13365-420: The most is mixing of the water column ( upwelling and downwelling along the coast and in the open ocean) that affects nutrient availability and, in turn, phytoplankton production. Through their consumption and processing of phytoplankton and other food sources, zooplankton play a role in aquatic food webs , as a resource for consumers on higher trophic levels (including fish), and as a conduit for packaging

13500-551: The natural level of atmospheric iron. Expanding this atmospheric source of iron could complement ship-based deployment. One proposal is to boost the atmospheric iron level with iron salt aerosol . Iron(III) chloride added to the troposphere could increase natural cooling effects including methane removal , cloud brightening and ocean fertilization, helping to prevent or reverse global warming. Martin hypothesized that increasing phytoplankton photosynthesis could slow or even reverse global warming by sequestering CO 2 in

13635-412: The ocean and its presence is vital for photosynthesis in plants, and in particular phytoplanktons, as it has been shown that iron deficiency can limit ocean productivity and phytoplankton growth. For this reason, the "iron hypothesis" was put forward by Martin in late 1980s where he suggested that changes in iron supply in iron-deficient seawater can bloom plankton growth and have a significant effect on

13770-417: The ocean floor where their carbonate skeletons can form a major component of the carbon-rich deep sea precipitation, thousands of meters below plankton blooms, known as marine snow . Nonetheless, based on the definition, carbon is only considered "sequestered" when it is deposited in the ocean floor where it can be retained for millions of years. However, most of the carbon-rich biomass generated from plankton

13905-424: The ocean surface has ample macronutrients, with little plant biomass (as defined by chlorophyll). The production in these high-nutrient low-chlorophyll (HNLC) waters is primarily limited by micronutrients , especially iron. The cost of distributing iron over large ocean areas is large compared with the expected value of carbon credits . Research in the early 2020s suggested that it could only permanently sequester

14040-474: The ocean to reduce the impacts of rising temperature. One approach is to add material such as lime or iron to the ocean to increase its ability to support marine life and/or sequester CO 2 . In 2021 the US National Academies of Sciences, Engineering, and Medicine (NASEM) requested $ 2.5 billion funds for research in the following decade, specifically including field tests. Another idea

14175-410: The ocean's nutrient balance. Controversy remains over the effectiveness of atmospheric CO 2 sequestration and ecological effects. Since 1990, 13 major large scale experiments have been carried out to evaluate efficiency and possible consequences of iron fertilization in ocean waters. A study in 2017 considered that the method is unproven; the sequestering efficiency was low and sometimes no effect

14310-440: The ocean. It is difficult for scientists to detect and analyse jellyfish in the guts of predators, since they turn to mush when eaten and are rapidly digested. But jellyfish bloom in vast numbers, and it has been shown they form major components in the diets of tuna , spearfish and swordfish as well as various birds and invertebrates such as octopus , sea cucumbers , crabs and amphipods . "Despite their low energy density,

14445-510: The oceans. Martin's 1988 quip four months later at Woods Hole Oceanographic Institution , "Give me a half a tanker of iron and I will give you an ice age ," drove a decade of research. Climate engineering Climate engineering (or geoengineering ) is the intentional large-scale alteration of the planetary environment to counteract anthropogenic climate change . The term has been used as an umbrella term for both carbon dioxide removal and solar radiation modification when applied at

14580-410: The oldest manifestations of the biogeography of traits was proposed over 170 years ago, namely Bergmann's rule , in which field observations showed that larger species tend to be found at higher, colder latitudes. In the oceans, size is critical in determining trophic links in planktonic ecosystems and is thus a critical factor in regulating the efficiency of the biological carbon pump . Body size

14715-590: The open ocean, began producing toxic levels of domoic acid . Even short-lived blooms containing such toxins could have detrimental effects on marine food webs. Most species of phytoplankton are harmless or beneficial, given that they constitute the base of the marine food chain. Fertilization increases phytoplankton only in the open oceans (far from shore) where iron deficiency is substantial. Most coastal waters are replete with iron and adding more has no useful effect. Further, it has been shown that there are often higher mineralization rates with iron fertilization, leading to

14850-531: The organic material in the biological pump . Since they are typically small, zooplankton can respond rapidly to increases in phytoplankton abundance, for instance, during the spring bloom . Zooplankton are also a key link in the biomagnification of pollutants such as mercury . Ecologically important protozoan zooplankton groups include the foraminiferans , radiolarians and dinoflagellates (the last of these are often mixotrophic ). Important metazoan zooplankton include cnidarians such as jellyfish and

14985-626: The particulate matter fell to between 100 metres (330 ft) to the ocean floor. Each iron atom converted at least 13,000 carbon atoms into algae. At least half of the organic matter sank below, 1,000 metres (3,300 ft). 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

15120-566: The place. Some dinoflagellates are known to be photosynthetic , but a large fraction of these are in fact mixotrophic , combining photosynthesis with ingestion of prey ( phagotrophy ). Some species are endosymbionts of marine animals and other protists, and play an important part in the biology of coral reefs . Others predate other protozoa, and a few forms are parasitic. Many dinoflagellates are mixotrophic and could also be classified as phytoplankton. The toxic dinoflagellate Dinophysis acuta acquire chloroplasts from its prey. "It cannot catch

15255-642: The plankton community. As the primary consumers of marine phytoplankton, microzooplankton consume ~ 59–75% daily of the marine primary production , much larger than mesozooplankton. That said, macrozooplankton can sometimes have greater consumption rates in eutrophic ecosystems because the larger phytoplankton can be dominant there. Microzooplankton are also pivotal regenerators of nutrients which fuel primary production and food sources for metazoans. Despite their ecological importance, microzooplankton remain understudied. Routine oceanographic observations seldom monitor microzooplankton biomass or herbivory rate, although

15390-417: The putative explanation for annual cycles in phytoplankton biomass, accumulation rates and export production. In addition to linking primary producers to higher trophic levels in marine food webs , zooplankton also play an important role as “recyclers” of carbon and other nutrients that significantly impact marine biogeochemical cycles , including the biological pump . This is particularly important in

15525-540: The rate of warming this century". In 2009, a review examined the scientific plausibility of proposed methods rather than the practical considerations such as engineering feasibility or economic cost. The authors found that "[air] capture and storage shows the greatest potential, combined with afforestation , reforestation and bio-char production", and noted that "other suggestions that have received considerable media attention, in particular, "ocean pipes" appear to be ineffective". They concluded that "[climate] geoengineering

15660-444: The relative atomic concentrations of critical nutrients in plankton biomass and is conventionally written "106 C: 16 N: 1 P." This expresses the fact that one atom of phosphorus and 16 of nitrogen are required to " fix " 106 carbon atoms (or 106 molecules of CO 2 ). Research expanded this constant to "106 C: 16 N: 1 P: .001 Fe" signifying that in iron deficient conditions each atom of iron can fix 106,000 atoms of carbon, or on

15795-560: The resulting algal bloom died and sank to the sea floor. Planktos was a US company that abandoned its plans to conduct 6 iron fertilization cruises from 2007 to 2009, each of which would have dissolved up to 100 tons of iron over a 10,000 km 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. In 2007 commercial companies such as Climos and GreenSea Ventures and

15930-547: The right to deliberately change the climate, and under what conditions. For example, using climate engineering to stabilize temperatures is not the same as doing so to optimize the climate for some other purpose. Some religious traditions express views on the relationship between humans and their surroundings that encourage (to conduct responsible stewardship) or discourage (to avoid hubris) explicit actions to affect climate. A large 2018 study used an online survey to investigate public perceptions of six climate engineering methods in

16065-435: The same study, fecal pellet leaching was found to be an insignificant contributor. For protozoan grazers, DOM is released primarily through excretion and egestion and gelatinous zooplankton can also release DOM through the production of mucus. Leaching of fecal pellets can extend from hours to days after initial egestion and its effects can vary depending on food concentration and quality. Various factors can affect how much DOM

16200-602: The sea. He died shortly thereafter during preparations for Ironex I, a proof of concept research voyage, which was successfully carried out near the Galapagos Islands in 1993 by his colleagues at Moss Landing Marine Laboratories . Thereafter 12 international ocean studies examined the phenomenon: John Martin , director of the Moss Landing Marine Laboratories , hypothesized that the low levels of phytoplankton in these regions are due to

16335-428: The sequestration. Alkaline additives become diluted and dispersed in one month, without durable effects, such that if necessary, the program could be ended without leaving long-term effects. Enhancing the natural marine sulfur cycle by fertilizing a small portion with iron —typically considered to be a greenhouse gas remediation method—may also increase the reflection of sunlight. Such fertilization, especially in

16470-455: The so-called "jelly web" is only beginning to be understood, but it seems medusae, ctenophores and siphonophores can be key predators in deep pelagic food webs with ecological impacts similar to predator fish and squid. Traditionally gelatinous predators were thought ineffectual providers of marine trophic pathways, but they appear to have substantial and integral roles in deep pelagic food webs . Grazing by single-celled zooplankton accounts for

16605-530: The surface can stimulate a bloom using less iron. The iron will be confined within a plastic bag reaching from the surface several kilometers down to the sea bottom. The Centre for Climate Repair at the University of Cambridge, along with India's Institute of Maritime Studies assessed the impact of iron seeding in another experiment. They spread iron-coated rice husks across an area of the Arabian Sea. Iron

16740-543: The surface, where planktons can take it up to grow. It has been shown that reduction in the number of sperm whales in the Southern Ocean has resulted in a 200,000 tonnes/yr decrease in the atmospheric carbon uptake, possibly due to limited phytoplankton growth. Phytoplankton is photosynthetic : it needs sunlight and nutrients to grow, and takes up carbon dioxide in the process. Plankton can take up and sequester atmospheric carbon through generating calcium or silicon-carbonate skeletons. When these organisms die they sink to

16875-511: The temperature-size rule (TSR), has been observed for a wide range of ectotherms, including single-celled and multicellular species, invertebrates and vertebrates. The processes underlying the inverse relationship between body size and temperature remain to be identified. Despite temperature playing a major role in shaping latitudinal variations in organism size, these patterns may also rely on complex interactions between physical, chemical and biological factors. For instance, oxygen supply plays

17010-402: The urgency of reducing carbon emissions, a form of moral hazard . Also, most efforts have only temporary effects, which implies rapid rebound if they are not sustained. The Union of Concerned Scientists points to the danger that the use of climate engineering technology will become an excuse not to address the root causes of climate change, slow our emissions reductions and start moving toward

17145-407: The water column, which can thus alter the carbon composition of the pellet. This affects how much carbon is recycled in the euphotic zone and how much reaches depth. Fecal pellet contribution to carbon export is likely underestimated; however, new advances in quantifying this production are currently being developed, including the use of isotopic signatures of amino acids to characterize how much carbon

17280-514: The world's surface is covered in oceans. The part of these where light can penetrate is inhabited by algae (and other marine life). In some oceans, algae growth and reproduction is limited by the amount of iron. Iron is a vital micronutrient for phytoplankton growth and photosynthesis that has historically been delivered to the pelagic sea by dust storms from arid lands. This Aeolian dust contains 3–5% iron and its deposition has fallen nearly 25% in recent decades. The Redfield ratio describes

17415-413: The zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals. Gelatinous zooplankton include ctenophores , medusae , salps , and Chaetognatha in coastal waters. Jellyfish are slow swimmers, and most species form part of the plankton. Traditionally jellyfish have been viewed as trophic dead ends, minor players in

17550-486: Was communicated in around 2018, see for example the " Special Report on Global Warming of 1.5 °C ". According to climate economist Gernot Wagner the term geoengineering is "largely an artefact and a result of the term's frequent use in popular discourse" and "so vague and all-encompassing as to have lost much meaning". Specific technologies that fall into the "climate engineering" umbrella term include: The following methods are not termed climate engineering in

17685-549: 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 experimental area. The success of this experiment and others led to proposals to use this technique to remove carbon dioxide from the atmosphere. In 2000 and 2004, iron sulfate was discharged from the EisenEx. 10 to 20 percent of

17820-577: Was negligible compared to what naturally enters the ocean. Some environmentalists called the dumping a "blatant violation" of two international moratoria. George said that the Old Massett Village Council and its lawyers approved the effort and at least seven Canadian agencies were aware of it. According to George, the 2013 salmon runs increased from 50 million to 226 million fish. However, many experts contend that changes in fishery stocks since 2012 cannot necessarily be attributed to

17955-454: Was recorded until the 1980s, when oceanographer John Martin of the Moss Landing Marine Laboratories renewed controversy on the topic with his marine water nutrient analyses. His studies supported Hart's hypothesis. These "desolate" regions came to be called " high-nutrient, low-chlorophyll regions " (HNLC). John Gribbin was the first scientist to publicly suggest that climate change could be reduced by adding large amounts of soluble iron to

18090-620: Was released in February 2015 and consists of two volumes: Reflecting Sunlight to Cool Earth and Carbon Dioxide Removal and Reliable Sequestration . In June 2023 the US government released a report that recommended conducting research on stratospheric aerosol injection and marine cloud brightening. As of 2024 the Coastal Atmospheric Aerosol Research and Engagement (CAARE) project was launching sea salt into

18225-594: Was seen and the amount of iron deposits needed to make a small cut in the carbon emissions would be in the million tons per year. However since 2021, interest is renewed in the potential of iron fertilization, among other from a white paper study of NOAA, the US National Oceanographic and Atmospheric Administration, which rated iron fertilization as having "moderate potential for cost, scalability and how long carbon might be stored compared to other marine sequestration ideas" Approximately 25 per cent of

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