Glacier Geoengineering May Have Unintended Consequences for Marine Ecosystems and Fisheries

[Geoengineering News]

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2025AV001732

Authors

Mark James Hopwood, Sascha Schiøtt, Hilde Oliver

First published: 19 August 2025

https://doi.org/10.1029/2025AV001732

Abstract

Numerous proposed geoengineering schemes to mitigate climate change and its consequences are now widely discussed in the scientific literature. Sea level rise is a clear example of the implications of climate change with a further committed rise of at least 2–3 m embedded within the Earth System from +1.5°C of global warming. A bold suggestion to reduce sea level rise is to install underwater barriers to reduce the inflow of oceanic heat around Antarctica and Greenland. Inflow of warm, saline water masses drives ice melt and the destabilization of tidewater glaciers. Whilst the basic theory that barriers would stem oceanic heat flow is uncontroversial, the extent to which barriers might reduce future ice mass loss is less certain. There are numerous concerns about the viability and side-effects of this proposed intervention. We use existing field observations and representative fjord-scale models for the Greenland's largest glacier, Sermeq Kujalleq in the Ilulissat Icefjord, to suggest that there is already sufficient evidence to conclude that artificial barrier installation would have negative regional implications for marine productivity. The effects on fisheries are a concern as negative implications for Greenland's regional fisheries are unlikely to be socially acceptable. Increasing “geoengineeringization” of the Earth Sciences is likely to continue in coming decades as society grapples with the challenges of slowing climate change and mitigating its consequences. To produce beneficial results, the technical and social viabilities of geoengineering concepts need to be considered in parallel, with the latter determined in a complex social, economic and cultural nexus.

Plain Language Summary

Around Antarctica and Greenland, the melting of marine-terminating glaciers and ice shelves is often driven by heat from the inflow of warm seawater. This is leading to the destabilization of ice and driving faster rates of global sea level rise. A widely discussed geoengineering concept is that the construction of artificial underwater barriers at strategic locations could be used to reduce the inflow of warm saline waters and possibly help stabilize sensitive ice sheet outflows into the ocean. This would theoretically reduce future sea level rise, although there are presently large uncertainties predicting to what extent ice melt would be reduced. Apart from the numerous engineering challenges in any such polar geoengineering scheme, there are critical concerns about the resulting side-effects. In a case study for Greenland's largest marine-terminating glacier, we use a combination of model results, field observations, and local knowledge to suggest that artificial barriers would negatively affect marine productivity. Negative impacts on fisheries raise critical questions about the social viability of any such scheme which need to be considered in parallel with, rather than after, the technical viability of barrier installation and function.

Key Points

Proposed geoengineering schemes to mitigate sea level rise include artificial sills/curtains to restrict flow of warm water toward glaciers

Field observations and representative models for Ilulissat Icefjord suggest this would likely have negative effects on regional fisheries

The social implications of geoengineering concepts for stakeholders need to be considered in parallel with the technical aspects

Source: AGU