Targeted interventions refer to a set of relatively locally applied methods for slowing down or even reversing specific impacts of climate change. This contrasts with global solar geoengineering which seeks to control temperatures through increasing albedo (reflectivity) and is inherently challenging for governance, and adaptation whereby protection of specific assets relies on the wealth and other features of the adaptive capacity of the actors involved. In this respect a targeted intervention that seeks to maintain the status quo of the system is ethically justifiable and analogous to mitigation (Moore et al. 2020).
Ice sheet conservation by blocking deep warm saline Atlantic water from entering fjords and melting the Greenland ice sheet where it goes afloat was studied in some economic detail by Hunt &Byers (2019). However, their glaciological and engineering analysis was relatively crude. A key aspect of the methodology however remains - to take advantage of the fact that most of the ice sheet mass loss occurs via a small fraction of the ice sheet perimeter and area. Jakobshavn is a key glacier in terms of its impact on sea level (contributing 4% of 20th century sea level rise by itself), but also culturally being the fastest flowing glacier in the Northern hemisphere, and a regular target of cruise ships and other iceberg tourism. Furthermore it, and the Ilulissat fjord it calves into, are important hunting and fishing resources for local inhabitants.
While the global sea level rise commitment form Jakobshavn is tiny compared with that from West Antarctica over the coming century or two, the presence of active indigenous communities in the Ilulissat region means that there are also social, cultural, economic and ecological impacts to consider, as well as local ecosystem service benefits as well as global impacts. Furthermore designing the system provides an incremental step on the ladder of increasing importance and difficulty that would culminate in the unstable Amundsen Sea sector of Antarctica.
Figure 1. Outline of a structure designed to block deep warm and salty water from melting a glacier. the Seabed anchored curtain is below the depth of most icebergs and unlikely to be damaged by storms. The flexible section is designed to bend when struck by deep iceberg keels, to be replaceable in pre-fabricated sections, with an estimated life time of around 30 years. Dynamic loads and density differences are automatically adjusted for by the buoyancy. A possible location for the structure would be the sill at the mouth of Ilulissat fjord where water depths are about 300 m. Click the image to it full size.