Geoengineering is not going to save the poles from climate change

As global carbon emissions continue to rise, questions loom over whether geoengineering can effectively halt the accelerated melting of the Greenland and Antarctic ice caps, preventing catastrophic sea level increases. A comprehensive review of five prominent geoengineering proposals suggests that, unfortunately, they may not provide a viable solution.

Martin Siegert from the University of Exeter highlights the danger of promoting unfeasible geoengineering approaches, which may obscure the pressing need to prioritize decarbonization efforts. “It becomes something that is working against what we need to do,” he warns.

In reviewing these five ideas, Siegert and his team employed six critical evaluation criteria: efficacy, practicality at required scales, affordability, international consensus durability, environmental risk assessments, and the potential to engender misplaced optimism.

One notable proposal aimed at Antarctica involves constructing massive “curtains” to block warm ocean currents from eroding crucial ice sheets. However, uncertainties regarding effectiveness abound. Team member Steven Chown from Monash University remarks, “Warm water may well be diverted from one ice shelf, but the question is where does it go?”

These curtains would need to be built at challenging ocean depths, requiring significant engineering resources in perilous conditions. Chown reflects on the practical difficulties: “Halves of research cruises to Antarctica often face diversions due to icebergs and sea ice hazards.”

For land-based glaciers, further concerns arise as rising temperatures may increase the accumulation of liquid water beneath the ice, speeding its flow into the sea. One radical idea proposes drilling extensive boreholes through thick ice layers to release this water. But Sammie Buzzard from Northumbria University expresses doubts, noting the monumental challenges in both locating water pockets and the drilling itself.

Another geoengineering concept involves spreading tiny hollow glass beads across the Arctic Ocean’s surface to enhance solar reflection. Yet, Chown points out that such actions could potentially exacerbate the situation. “Maintaining this cover would require 360 megatonnes of glass beads produced annually—equivalent to global plastic production, and preliminary tests revealed toxicity issues,” he states.

Stratospheric aerosol injection, an approach involving the release of materials like sulfur dioxide into the stratosphere to create reflective aerosols, presents additional complications when applied in polar regions. Valerie Masson-Delmotte from Paris-Saclay University asserts that this strategy could deplete the ozone layer and raise geopolitical tensions over compensation demands from affected countries.

Other suggested methods include thickening Arctic sea ice by spraying seawater upon it. Heïdi Sevestre states, “This would entail deploying millions of devices across dynamic, fractured ice regions—a daunting logistical challenge.”

Finally, fertilizing the Southern Ocean to enhance phytoplankton growth, which sequesters carbon, shows diminished promise based on prior trials; only one among twelve succeeded in carbon deposit at the seafloor. There’s also the potential risk of accelerating ocean oxygen depletion, leading to the release of other harmful greenhouse gases.

Masson-Delmotte expresses concerns regarding overly simplistic viewpoints on these geoengineering tactics, emphasizing the necessity of thorough understanding. “I think this work addresses such gaps,” she concludes.

Siegert reiterates that investing further resources into impracticable geoengineering approaches detracts from immediate action towards decarbonization. However, not all experts agree. Shaun Fitzgerald from the Centre for Climate Repair in Cambridge argues, “I don’t think enough is known about any of these approaches for them to be dismissed outright.”