Artificial upwelling

Oceans & marine

A school of juveniles of the Dusky spinefoot Siganus luridus (second)

Oceans play an important role in global heat transfer and carbon storage processes. As global temperatures and atmospheric carbon levels rise, some have suggested artificially modifying the vertical movement of water to enhance these processes.

Artificial upwelling (AU) is an idea to increase carbon uptake of upper ocean layers by fertilizing it with pumped-up colder nutrient-rich waters from the deep, which would encourage the biological sequestration of carbon through photosynthesis (NASEM 2022). Such fertilization occurs naturally in certain regions, and AU would thereby artificially reproduce this process. Many different upwelling technologies have been suggested (Pan et al. 2016), and several have been tested (NASEM 2022). Apart from being used as a CDR method, AU could have several side-benefits, for example as a means to increase fish stocks (GESAMP 2019), or hurricane mitigation (Launder 2017).

Technological Readiness Level (TRL)

Medium 2

AU has been studied for several decades in model simulations and indoor and outdoor experiments (NASEM, 2022). There have been several long running institutional research programs, like at Zhejiang University in China (See Wang and Zhang, 2023), and major national funded projects like the German GEOMAR Ocean artUp, (https://www.geomar.de/en/research/fb2/fb2-bi/research-topics/ocean-artificial-upwelling). There are also several commercial companies that explore the feasibility of AU (see for example Ocean Based Climate solutions: https://ocean-based.com/). Despite this significant interest in AU, many questions remain about the feasibility and effects of large scale deployment, as well as about the technological deployment.

Technological Readiness Level (TRL)

A technology with a TRL of 4-6: TRL 4 – validated in lab; TRL 5 – validated in relevant environment; TRL 6 – demonstrated in relevant environment

Scalability

Medium 2

It is unsure if AU would be sufficiently scalable, and, like other ocean fertilization measures, AU would likely be most effective in areas with a relative deficiency of nutrients (NASEM, 2022).

Scalability

Physically somewhat scalable; linear efficiency

Timeliness for near-future effects

Low 1

Due to the large uncertainties about AU, NASEM (2022) suggests that ‘model-based feasibility studies should lead the research agenda to identify optimal siting and scaling of pump networks and CDR potential.’

Timeliness for near-future effects

Implemented too late to make a significant difference

Northern + Arctic potential

Low 1

Northern + Arctic potential

No noticeable extra positive effect beyond the global average; technology is unsuited to the Arctic

Global potential

Low 1

Some research finds AU could have a potential positive climate effect. Oschlies et al’s (2010) model study for instance suggests that pumping deep water up could sequester 0.9 PgC per year, but note that 80% of that would be on land, not in the sea. ///However, most studies remain pessimistic about the ultimate CDR potential of AU. Dutreuil et al (2009) for example show that the increased amount of carbon present in the deeper waters would not lead to a decrease, but to an increased CO2 content in the atmosphere. Bauman et al (2014) write that: ‘Given the absence of positive supporting scientific evidence, we do not recommend pursuing geoengineering through artificial upwelling; our calculations indicate it is unfeasible and may amplify the warming trend it seeks to reduce.’ NASEM (2022) also summarizes that ‘The current state of knowledge … indicates that even a persistent and effective deployment of millions of functional pumps across the global ocean would not meet CDR goals for sequestration or permanence.’ Lawrence et al (2018) equally conclude that it seems unlikely that such techniques 'will contribute significantly' to emission reduction targets. Some nevertheless suggest it might be worthwhile to explore AU further, for example through natural analogues (Bach and Boyd, 2021), or because they think the technology could help study marine ecosystems (Wallace et al, 2010).

Global potential

Insignificant to be detected at a global scale

Cost - benefit

High 1

The costs are likely very high, although there are large uncertainties about possible development and deployment costs (NASEM, 2022).

Cost - benefit

Cost of investment comparable to cost of avoided damage

Environmental risks

High 1

Artificial upwelling and other interventions that interfere with deep ocean layers could have major environmental effects (Levin et al, 2023), and could severely impact local ecosystems (Bauman et al, 2014; Boyd et al, 2022), and potentially lead to ocean acidification (Williamson and Turley, 2012).

Environmental risks

Major, serious risks with a high disaster potential; multiple and cascading risks

Community impacts

Unknown 0

Ease of reversibility

Easy 3

Ease of reversibility

Easily reversible naturally

Risk of termination shock

High 1

Oschlies et al’s (2010), warn that a “termination shock” could occur when AU were to be abruptly halted, which would lead to rapid temperature rise that could be higher than if artificial upwelling would never have been done.

Risk of termination shock

High or very significant termination shock or damage

Legality/governance

Medium 2

Webb et al (2022) note that both AU and artificial downwelling would fall under national governance and legal frameworks, as well as international conventions like the United Nations Convention on the Law of the Sea, the Convention on Biological Diversity, the Convention on the Prevention of Marine Pollution by Dumping of Waste and Other Matter, and the Protocol to that Convention.

Legality/governance

Fits within existing structures to a certain degree, but some policy changes are needed to deploy at scale

Scientific/media attention

Medium 2

There has been significant scientific attention for AU, including major research projects. Apart from this institutional research, AU has been taken up by individual projects, and is often listed as one of the main Ocean based CDR techniques.

Scientific/media attention

Some attention within the scientific community, including published research and funding programmes; some media attention; some commercial interest

References

Bach, L. T., & Boyd, P. W. (2021). Seeking natural analogs to fast-forward the assessment of marine CO2 removal. Proceedings of the National Academy of Sciences, 118(40), e2106147118. https://doi.org/10.1073/pnas.2106147118

Bauman, S. J., Costa, M. T., Fong, M. B., House, B. M., Perez, E. M., Tan, M. H., ... & Franks, P. J. (2014). Augmenting the biological pump: The shortcomings of geoengineered upwelling. Oceanography, 27(3), 17-23. https://doi.org/10.5670/oceanog.2014.79

Boyd, P.W., Bach, L.T., Hurd, C.L. et al. Potential negative effects of ocean afforestation on offshore ecosystems. Nat Ecol Evol 6, 675–683 (2022). https://doi.org/10.1038/s41559-022-01722-1

Dutreuil, S., Bopp, L., & Tagliabue, A. (2009). Impact of enhanced vertical mixing on marine biogeochemistry: lessons for geo-engineering and natural variability. Biogeosciences, 6(5), 901-912. https://doi.org/10.5194/bg-6-901-2009

Hunt, J. D., Nascimento, A., Diuana, F. A., de Assis Brasil Weber, N., Castro, G. M., Chaves, A. C., ... & Schneider, P. S. (2020). Cooling down the world oceans and the earth by enhancing the North Atlantic Ocean current. SN Applied Sciences, 2(1), 1-15. https://doi.org/10.1007/s42452-019-1755-y

Launder, B. (2017). Hurricanes: an engineering view of their structure and strategies for their extinction. Flow, Turbulence and Combustion, 98, 969-985. https://doi.org/10.1007/s10494-016-9793-7

Lawrence, M.G., Schäfer, S., Muri, H. et al. Evaluating climate geoengineering proposals in the context of the Paris Agreement temperature goals. Nat Commun 9, 3734 (2018). https://doi.org/10.1038/s41467-018-05938-3

Lovelock, J. E., & Rapley, C. G. (2007). Ocean pipes could help the Earth to cure itself. Nature, 449(7161), 403-403.

Oschlies, A., Pahlow, M., Yool, A., & Matear, R. J. (2010). Climate engineering by artificial ocean upwelling: Channeling the sorcerer's apprentice. Geophysical Research Letters, 37(4). https://doi.org/10.1038/449403a

Wallace, D., Law, C., Boyd, P., Collos, Y., Croot, P., Denman, K., ... & Williamson, P. (2010). Ocean fertilization: a scientific summary for policy makers. UNESCO. Available at: https://unesdoc.unesco.org/ark:/48223/pf0000190674 [Accessed 19 July 2024]

Wang, Weijie and Zhang, Junjie, (2023), Ocean-based carbon dioxide removal landscape in China. Climateworks Foundation, available at: https://www.climateworks.org/report/ocean-based-carbon-dioxide-removal-landscape-in-china

Williamson, P., & Turley, C. (2012). Ocean acidification in a geoengineering context. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 370(1974): 4317-4342. https://doi.org/10.1098/rsta.2012.0167

Zhou, S., & Flynn, P. C. (2005). Geoengineering downwelling ocean currents: a cost assessment. Climatic change, 71(1), 203-220. https://doi.org/10.1007/s10584-005-5933-0

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