We disagree with John Moore and colleagues that geoengineering could counter rising sea levels from the melting of the Greenland and Antarctic ice sheets (Nature 555, 303–305; 2018). As environmental researchers in these regions, we contend that the consequences of the technology could be even more serious than in its absence.
The authors’ suggestions (building ocean-bottom sills, installing pinning-point islands and removing subglacial water) might briefly slow outflow. However, these strategies could easily cause ice build-up that would overwhelm structural impediments, and further accelerate ice loss.
Even if feasible, slowing the flow of glaciers such as Jakobshavn Isbrae is only a partial solution, given that more than half of ice loss in Greenland is due to surface melt. And the logistical difficulties of transporting the unprecedented amounts of equipment and materials required needs to be taken into account. The Amundsen Sea in western Antarctica, for example, is often inaccessible to icebreakers. And the water-pumping system Moore et al. propose would have to extend over almost the entire glacier catchment to avoid water pooling or redirection.
In our view, the limited resources available should instead be used to address the root causes of accelerating ice loss — namely emissions and human-induced climate change.
Nature 556, 436 (2018)