Half of sea-level rise comes from ice flow into the ocean, this flow can be slowed by removing lubricating water from bed of the ice.
Ice streams of Antarcitca and outlet glaciers of Greenland contribute to sea level rise when they discharge more icebergs into the ocean than the volume of ice accumulated as snow in their catchment area. These glacial flow features depend strongly on water conditions at their bed (the interface between the ice and the substratum consisting of bedrock or muddy layers above bedrock). Only a small volume of water in the subglacial bed can lubricate (reduce basal friction) and accelerate ice flow. If this water is removed by artificial means (drilling and pumping), not only will the ice slow down, but it may also freeze to the bed, thereby adding friction and slowing ice discharge.
Category of the action
What actions do you propose?
The first step would be to evaluate using theory and "back of envelope" calculation. The second step would be to examine conditions at small glaciers where bed access is possible (for reasonable funding).
Who will take these actions?
The glaciological community would have to team up with the "wizzards of drilling and hydrofracking" that are currently so adept at delivering fossil fuel to the surface from "tight" shale-oil reserves in, for example, the states of Pennsylvania and Ohio.
Where will these actions be taken?
Countries with high-exposure to sea level rise should consider whether a mitigation scheme at their coastal cities might be made easier or offset by mitigating at the source of ice flow. Conferences should be held in these countries to get a sense of whether there is merit in this idea.
What are other key benefits?
Countries could collaborate on mitigating sea level rise at the "source". Otherwise, it is "every coastal city for itself"...
What are the proposal’s costs?
If it costs 5% of the 30 Trillion US$ of coastal infrastructure at risk of sea level rise of 3 m or greater to protect that infrastructure, then 1.5 Trillion $US could be put to work on this.
Fortunately, the time line for sea level rise of the order of 40 cm is about 50 years. Probably 40 cm is something that can be dealt with, but going higher would be something to stop, and figuring out how to do it over 50 years is doable.
I've seen other proposals, e.g., pumping water back to the top of the Antarctic Ice Sheet out of the ocean to "remove" it from the ocean.
Generally speaking: These kinds of ideas are very risky for glaciologists to publish (as all glaciologists believe that the best solution is to mitigate the cause, i.e., reduce emissions), hence there is not yet a forum for exchange of ideas on this kind of geoengineering consideration.