Ice sheet stabilization via seabed curtains

Ice sheets and glaciers

Melting glacier ice, Rødefjord, Northeast Greenland National Park (1)

One of the potentially most catastrophic effects of contemporary global warming would be the dramatic increase in sea levels as a result of the melting Greenland and Antarctic ice sheets. Even if all current emissions were immediately stopped, sea level rise could still occur because of locked-in warming (State of the Cryosphere report 2022).

There have been several suggested “Glacier geoengineering” measures (Lockley et al. 2020). The only one that is being seriously explored at this time would attempt to increase ice sheet stability by blocking the warmer deep water access from the ocean to terminating glaciers or floating ice sheets. Although larger physical dams have been previously suggested (Wolovick and Moore 2018; Hunt and Byers 2018), a curtain design is considered more feasible. These curtains would be anchored to the ground and would block most of the warmer waters, whilst still being flexible enough to allow icebergs to pass over them (Keefer et al., 2023; Wolovick et al. 2023). Research is still being done on how to best deploy such a measure, and which sites would provide the greatest benefit whilst still being feasible to build.

Technological Readiness Level (TRL)

Low 1

Although the project is still in an initial state, it is seeing rapid expansion, and now includes several private engineering firms that aim to provide more clarity about pending questions about preferred materials, and design elements (see akersolutions.com/news/news-archive/2022/aker-solutions-explores-first-of-a-kind-engineering-solution-to-slow-melting-of-glaciers/). The feasibility of the underwater curtain design has been shown in other applications in which it separates water at different temperatures. After model and computer simulations, a small variant of the curtain could be tested at accessible fjords, for example on Svalbard, after which larger construction projects in more difficult locations could be done.

Technological Readiness Level (TRL)

A technology with a TRL of 1-3: TRL 1 – Basic; TRL 2 – Concept formulated; TRL 3 – Experimental proof of concept

Scalability

Medium 2

There are only a handful of glaciers where a curtain deployment could potentially prevent meters of global sea level. The project could advance, step-by-step, to more challenging locations from easy accessible Arctic locations to Greenland and eventually to Antarctica. However, as part of the melting is also the result of rising atmospheric temperatures, especially in Greenland, it is not yet sure how effective such curtains ultimately would be in all suggested locations.

Scalability

Physically somewhat scalable; linear efficiency

Timeliness for near-future effects

Medium 2

It might take two to three decades of development before this measure would be deployed in Antarctica. As the most serious Antarctic instability is not predicted until later this century, if research were to start now, this would still be timely.

Timeliness for near-future effects

Implemented in time to make some difference, although questionable

Northern + Arctic potential

Unknown 0

Apart from the positive effect of potentially mitigating sea level rise through a deployment in Antarctica, seabed curtains could potentially also be installed in Greenland. However, this method might be less effective there, as, in contrast to Antarctica, the melt in Greenland is at least half the result of atmospheric warming, which this measure would not be able to mitigate.

Global potential

High 3

Global sea level rise will be one of the most impactful results of current global warming. West Antarctica alone holds enough water to potentially raise sea levels by 6 meters. Any intervention that would prevent or reduce sea level rise would therefore be highly important.

Global potential

Major impacts detected

Cost - benefit

Low 3

The cost estimates for curtain construction crucially depend on several variables like location, size, and depth. Hunt and Byers (2018) earlier gave a figure for the final cost of a barrier would as US$ 68.9 billion, with submerged dams built at a cost of US$ 337.1 billion.

Keefer et al. (2023) estimate that an 80 km curtain at 600 m depth could be built at Pine Island and Thwaites glaciers for $40–80 billion + $1–2 billion/yr maintenance. Although this sounds expensive, they note this would also be needed yearly to build global protections as a result of the sea level rise that would follow the collapse of both glaciers. The costs for this measure would therefore ultimately only be 1 to 2 % of the total amount of money that would be needed for global coastal protection this century if sea level rise is left unmitigated.

Cost - benefit

Low investment cost compared to the avoided damage cost (e.g., a few %) and/or inexpensive relative to other measures with similar impact

Environmental risks

Unknown 0

The environmental effects of such constructions are unknown. The earlier conceived physical dams would likely have had a much greater environmental impact, although the construction of curtains will also inevitably cause disturbances. A curtain could for example locally interfere with glacial runoff regimes and thereby influence marine bioproductivity that thrives on the associated nutrients. However, these potential effects of deployment will have to be weighed against the major ecological disturbances ice sheet retreat and potential collapse will have.

Community impacts

Unknown 0

The project has attempted to co-create and build collaborations in Ilulissat, Greenland (see arcticcentre.org/EN/grisco). Depending on the environmental and ecological effects of deployment, local livelihoods might be positively or negatively impacted.

Ease of reversibility

Medium 2

In contrast to dams or other fixed constructions, the curtain is only fixed to the seafloor at the anchoring points, and could therefore be relatively easily removed if desired (Keefer et al. 2023).

Ease of reversibility

Possible with significant investment

Risk of termination shock

Medium 2

If suddenly removed there might be some risk of destabilization.

Risk of termination shock

Medium or relatively significant termination shock or damage

Legality/governance

Medium 2

Corbett and Parson (2022) conclude that such intervention would currently not fit into Antarctic governance structures, but they say they are very hopeful it will adjust to include it in the future.

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

The idea has received some public attention and has for example been featured in the New Scientist (www.newscientist.com/article/2343633-engineering-firms-explore-plan-to-slow-melting-of-greenland-glacier/). The research program is mostly led by John Moore at the University of Lapland, Finland, with international collaboration.

Scientific/media attention

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

References

Corbett, C. R., & Parson, E. A. (2022). Radical climate adaptation in Antarctica. Ecology LQ, 49, 77. http://dx.doi.org/10.2139/ssrn.3992585

Hunt, J. D., & Byers, E. (2019). Reducing sea level rise with submerged barriers and dams in Greenland. Mitigation and Adaptation Strategies for Global Change, 24, 779-794. https://doi.org/10.1007/s11027-018-9831-y

Keefer, B., Wolovick, M., & Moore, J. C. (2023). Feasibility of ice sheet conservation using seabed anchored curtains. PNAS nexus, 2(3), pgad053. https://doi.org/10.1093/pnasnexus/pgad053

Lockley, A., Wolovick, M., Keefer, B., Gladstone, R., Zhao, L. Y., & Moore, J. C. (2020). Glacier geoengineering to address sea-level rise: A geotechnical approach. Advances in Climate Change Research, 11(4), 401-414. https://doi.org/10.1016/j.accre.2020.11.008

Moore, J. C., Gladstone, R., Zwinger, T., & Wolovick, M. (2018). Geoengineer polar glaciers to slow sea-level rise. Nature, 555(7696), 303-305. https://doi.org/10.1038/d41586-018-03036-4

Moore, J. C., Mettiäinen, I., Wolovick, M., Zhao, L., Gladstone, R., Chen, Y., ... & Koivurova, T. (2021). Targeted geoengineering: local interventions with global implications. Global Policy, 12, 108-118. https://doi.org/10.1111/1758-5899.12867

Wolovick, M. J., & Moore, J. C. (2018). Stopping the flood: could we use targeted geoengineering to mitigate sea level rise?. The Cryosphere, 12(9), 2955-2967. https://doi.org/10.5194/tc-12-2955-2018

Wolovick, M., Moore, J., & Keefer, B. (2023). The potential for stabilizing Amundsen Sea glaciers via underwater Curtains. PNAS Nexus, pgad103. https://doi.org/10.1093/pnasnexus/pgad103

Zhang, Z., Moore, J. C., Huisingh, D., & Zhao, Y. (2015). Review of geoengineering approaches to mitigating climate change. Journal of Cleaner Production, 103, 898-907. https://doi.org/10.1016/j.jclepro.2014.09.076

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Oceans & marine

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Agriculture landscape with small villages and forests in Baden Würtemberg, Germany

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Atmosphere / solar radiation

Mixed phase regime cloud thinning over the polar oceans during winter

Clouds play an important role in the Earth’s energy system. The effects of clouds are complex and diverse, often having simultaneous cooling and warming effects. Mixed-phase clouds (MPC) are clouds that contain water vapor, ice particles, and supercooled water droplets. MPCs are still poorly understood and 'notoriously difficult to represent in numerical weather prediction and climate models' (Korolev et al. 2017).