Experts warn polar geoengineering schemes could cause irreversible damage to Antarctica and Arctic

A multinational group of more than 40 scientists has warned that a range of controversial geoengineering proposals aimed at the polar regions could inflict irreversible harm on Antarctica and the Arctic, and are unlikely to deliver the intended climate benefits.

In a paper published Tuesday in the journal Frontiers in Science, the authors review several high-profile and lesser-known polar interventions — including stratospheric aerosol injection, so-called sea curtains, scattering reflective glass beads, ocean fertilization, artificial sea-ice thickening and drilling to slow ice movement — and conclude that each carries large uncertainties, substantial environmental risks and severe logistical obstacles.

"These ideas are often well-intentioned, but they’re flawed," said lead author Martin Siegert of the University of Exeter. "Deploying any of these polar projects is likely to work against the polar regions and the planet." The authors said the proposals could disrupt wildlife, alter sensitive physical processes and introduce contaminants to largely pristine and poorly understood environments.

Stratospheric aerosol injection (SAI), commonly described as "dimming the sun," is among the most debated techniques. The method would release tiny sulfur dioxide particles into the stratosphere to form sulfate aerosols that reflect sunlight, producing a cooling effect analogous to major volcanic eruptions. The paper notes health and environmental hazards from sulfur dioxide and related particles, potential regional air-quality impacts, limits on year-round effectiveness in polar latitudes because of winter darkness, and the large and costly delivery platforms that would be required, including specialized aircraft, balloons or other vehicles. The authors also highlighted the risk of a "termination shock": a rapid warming that could follow an abrupt halt in aerosol deployment.

Proposals to erect submerged barriers, dubbed "sea curtains," are advanced as a way to prevent warmer deep water from reaching and undermining ice shelves. The review finds the scale of such structures would be vast, potentially exceeding the transport capabilities of existing ships, and that their presence could alter ocean circulation and nutrient delivery, with negative consequences for marine ecosystems. The composition and installation of the curtains could also introduce pollutants into the water column.

Another reflective-surface idea involves spreading hollow glass beads over seasonal sea ice to increase albedo, the amount of sunlight reflected back into space. The authors say the approach would require extraordinary quantities — roughly 360 megatons annually, an amount comparable to current global annual plastic production — and pose risks to zooplankton and other organisms that could ingest the beads. Production and distribution would generate substantial emissions and costs, and deployment logistics appear daunting.

Ocean fertilization, usually proposed through iron additions to surface waters to stimulate phytoplankton growth and draw down carbon dioxide, is described as similarly problematic. The review warns that changing nutrient balances at scale could create hypoxic "dead zones," harm food webs, and promote toxin-producing species. The authors estimate that treated areas would need to be many times larger than the Southern Ocean to have a meaningful global effect, requiring fleets of specially adapted vessels to spread material across ocean basins.

Ideas to thicken sea ice by pumping seawater onto ice surfaces or spraying seawater into the air to fall as snow are characterized as technically simple in concept but logistically infeasible at the scale required. Prior modeling cited by the authors suggested a theoretical thickening of about 1 metre in targeted areas, but achieving significant coverage would demand millions of wind-powered pumps — the paper references an estimate of 10 million devices to cover 10 percent of the Arctic Ocean and 100 million to cover the whole basin — and would need to be deployed immediately and maintained through harsh winter conditions.

A final class of proposals would attempt to slow the flow of ice from Antarctica by drilling to the ice-sheet base to increase basal friction. The review calls such interventions "scientifically flawed and likely to be logistically impossible," noting the risk of introducing surface-derived contaminants into subglacial environments and damaging fragile, largely unknown ecosystems beneath the ice. Widespread drilling across ice sheets would also present unprecedented operational challenges.

Across the reviewed concepts, the authors highlight three common themes: uncertainty about whether the interventions would achieve their goals, large knowledge gaps about costs and side effects, and risks that deployment could produce unintended, potentially long-lasting harm. They also note governance challenges, since unilateral or limited-area deployments of climate-altering technologies could have cross-border and global consequences.

The scientists urged policymakers and the research community to prioritize rapid and deep reductions in greenhouse gas emissions rather than large-scale manipulations of polar environments. "Decarbonization remains the obvious alternative to these costly and risky schemes," the paper states, calling for continued investment in emissions cuts and adaptation measures.

The paper follows growing international debate over geoengineering. Small-scale experiments in solar radiation management and other techniques have already taken place, and researchers at institutions including Yale have proposed localized SAI deployments as a way to reduce ice loss. The authors of the Frontiers paper emphasized that such studies underscore the need for rigorous risk assessment, transparent governance and clear international limits on field trials in polar regions.

The review provides a consolidated appraisal of the proposals most often discussed in public and academic forums and frames them as hazardous and unproven when applied to the polar environment. It calls for stronger international scrutiny, further research into ecological and physical impacts, and policies that center emission reductions to limit warming and protect polar systems.

The journal paper and its accompanying briefing do not categorically rule out all forms of geoengineering, but they emphasize that interventions targeted at the poles raise particular concerns because of the regions' ecological sensitivity, the complexity of ice–ocean–atmosphere interactions, and the potential for long-term, irreversible changes that would be difficult or impossible to reverse.