Ocean Iron Fertilization--Moving Forward in a Sea of Uncertainty

Buesseler, Ken O.; Doney, Scott C.; Karl, David M.; Boyd, Philip W.; Caldeira, Ken; Chai, Fei; Coale, Kenneth H.; Baar, H. J. W. de; Falkowski, Paul G.; Johnson, Kenneth S.; Lampitt, Richard S.; Michaels, Anthony F.; Naqvi, S.W.A.; Smetacek, Victor; Takeda, Shigenobu; Watson, Andrew J.

doi:10.1126/science.1154305

Cited by 165 publications

(124 citation statements)

References 5 publications

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“…While few continental margin systems have been investigated directly in terms of the consequences of climate change, their strong gradients and regional variations have allowed significant understanding of the effects of temperature, pH, O 2 and POC flux on deep-sea benthic ecosystems. Warming of surface waters along continental margins, and increased thermal stratification and reduced nutrient supply to the surface are likely to reduce both productivity and phytoplankton type and size Morán et al, 2010Morán et al, , 2015, yielding reduced phytodetrital flux to the seabed Buesseler et al, 2008;. Model outputs suggest that bathyal areas particularly prone to declining POC flux lie in the Norwegian and Caribbean Seas, NW and NE Atlantic, the eastern tropical Pacific, and bathyal Indian and Southern Oceans, which could experience as much as a 55% decline in POC flux by 2100 (Tables 2, 3; Figures 2, 3).…”

Section: Seafloor Ecosystem Changes Under Future Climate Change Scenamentioning

confidence: 99%

Major impacts of climate change on deep-sea benthic ecosystems

Sweetman

Thurber

Smith

et al. 2017

Elementa: Science of the Anthropocene

282

297

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The deep sea encompasses the largest ecosystems on Earth. Although poorly known, deep seafloor ecosystems provide services that are vitally important to the entire ocean and biosphere. Rising atmospheric greenhouse gases are bringing about significant changes in the environmental properties of the ocean realm in terms of water column oxygenation, temperature, pH and food supply, with concomitant impacts on deep-sea ecosystems. Projections suggest that abyssal (3000-6000 m) ocean temperatures could increase by 1°C over the next 84 years, while abyssal seafloor habitats under areas of deep-water formation may experience reductions in water column oxygen concentrations by as much as 0.03 mL L -1 by 2100. Bathyal depths (200-3000 m) worldwide will undergo the most significant reductions in pH in all oceans by the year 2100 (0.29 to 0.37 pH units). O 2 concentrations will also decline in the bathyal NE Pacific and Southern Oceans, with losses up to 3.7% or more, especially at intermediate depths. Another important environmental parameter, the flux of particulate organic matter to the seafloor, is likely to decline significantly in most oceans, most notably in the abyssal and bathyal Indian Ocean where it is predicted to decrease by 40-55% by the end of the century. Unfortunately, how these major changes will affect deep-seafloor ecosystems is, in some cases, very poorly understood. In this paper, we provide a detailed overview of the impacts of these changing environmental parameters on deep-seafloor ecosystems that will most likely be seen by 2100 in continental margin, abyssal and polar settings. We also consider how these changes may combine with other anthropogenic stressors (e.g., fishing, mineral mining, oil and gas extraction) to further impact deep-seafloor ecosystems and discuss the possible societal implications.

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Section: Seafloor Ecosystem Changes Under Future Climate Change Scenamentioning

confidence: 99%

Major impacts of climate change on deep-sea benthic ecosystems

Sweetman

Thurber

Smith

et al. 2017

Elementa: Science of the Anthropocene

282

297

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“…The prospects for fertilization of low-productivity waters in the ocean to increase their productivity have been the subject of intense scientific interest and commercial speculation [2,3]. Such approaches belong to the CDR category of putative climate geo-engineering solutions [4].…”

Section: Introductionmentioning

confidence: 99%

Impacts of light shading and nutrient enrichment geo-engineering approaches on the productivity of a stratified, oligotrophic ocean ecosystem

Hardman-Mountford

Polimene

Hirata

et al. 2013

J. R. Soc. Interface.

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Geo-engineering proposals to mitigate global warming have focused either on methods of carbon dioxide removal, particularly nutrient fertilization of plant growth, or on cooling the Earth's surface by reducing incoming solar radiation (shading). Marine phytoplankton contribute half the Earth's biological carbon fixation and carbon export in the ocean is modulated by the actions of microbes and grazing communities in recycling nutrients. Both nutrients and light are essential for photosynthesis, so understanding the relative influence of both these geo-engineering approaches on ocean ecosystem production and processes is critical to the evaluation of their effectiveness. In this paper, we investigate the relationship between light and nutrient availability on productivity in a stratified, oligotrophic subtropical ocean ecosystem using a one-dimensional water column model coupled to a multi-plankton ecosystem model, with the goal of elucidating potential impacts of these geo-engineering approaches on ecosystem production. We find that solar shading approaches can redistribute productivity in the water column but do not change total production. Macronutrient enrichment is able to enhance the export of carbon, although heterotrophic recycling reduces the efficiency of carbon export substantially over time. Our results highlight the requirement for a fuller consideration of marine ecosystem interactions and feedbacks, beyond simply the stimulation of surface blooms, in the evaluation of putative geo-engineering approaches.

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“…de Barr et al 2005, Lutz et al 2007, Buesseler et al 2008. Carbon production and transport following iron enrichment were found to be dependent on light, temperature, depth of the mixed layer, and grazing (de Baar et al 2005).…”

Section: Urea Fertilization Not Likely To Sequester Carbon To the Deementioning

confidence: 99%

“…Iron experiments, now totaling more than a dozen (de Baar et al 2005, Boyd et al 2007, Buesseler et al 2008, have shown that phytoplankton blooms can be successfully manufactured, and this has caught the attention of the business community as a means to promote engineered solutions to climate change. The carbon-offsets market is rapidly expanding, and new enterprises are seeking methods to sequester atmospheric carbon as part of cap-and-trade programs.…”

Section: Introductionmentioning

confidence: 99%

“…Most of these experiments have involved iron additions to the equatorial North Pacific, the subarctic Pacific, and the Southern Ocean, which are regions known as high-nutrient, low-chlorophyll (HNLC) areas where there is apparent ample macro-nutrient availability (nitrogen, phosphorus), but limited micro-nutrients (iron), and thus limited phytoplankton accumulation (de Baar et al 2005, Boyd et al 2007, Buesseler et al 2008. Application of such research has led some to suggest that with such ocean enrichment, carbon sequestration can be enhanced, and this may serve as one approach to reduce the build-up of greenhouse gases in the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

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Ocean urea fertilization for carbon credits poses high ecological risks

Glibert¹,

Azanza²,

Burford³

et al. 2008

Marine Pollution Bulletin

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The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.

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Ocean Iron Fertilization--Moving Forward in a Sea of Uncertainty

Cited by 165 publications

References 5 publications

Major impacts of climate change on deep-sea benthic ecosystems

Major impacts of climate change on deep-sea benthic ecosystems

Impacts of light shading and nutrient enrichment geo-engineering approaches on the productivity of a stratified, oligotrophic ocean ecosystem

Ocean urea fertilization for carbon credits poses high ecological risks

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