Scientists Warn Polar Geoengineering Plans Could Cause Irreversible Damage

A team of more than 40 scientists warned Tuesday that a range of controversial geoengineering proposals aimed at the polar regions could inflict irreversible damage on fragile Arctic and Antarctic environments and are unlikely to be feasible or effective.

In a paper published in the journal Frontiers in Science, the international group said schemes ranging from "dimming the sun" by spraying particles into the stratosphere to installing underwater "sea curtains" or scattering hollow glass beads over sea ice carry high costs, substantial logistical barriers and serious ecological risks. "These ideas are often well-intentioned, but they’re flawed," said lead author Martin Siegert, a professor at the University of Exeter. "Deploying any of these polar projects is likely to work against the polar regions and planet."

The most prominent and widely discussed proposal is stratospheric aerosol injection (SAI), sometimes described as "dimming the sun." SAI would release tiny sulfur dioxide particles into the stratosphere to form sunlight-reflecting sulfate aerosols, producing a cooling effect similar to the aftermath of a large volcanic eruption. Proponents have argued SAI could slow ice loss at high latitudes and help avoid dangerous temperature thresholds, but the authors cautioned it could bring air-pollution harms and health risks if deployed at high levels. They also noted that polar deployment is seasonally constrained by winter darkness and would require costly delivery systems such as aircraft, balloons, airships or even artillery.

Other proposals the authors reviewed include sea curtains, enormous underwater structures designed to block warmer deep water from reaching the bases of ice shelves. Advocates assert such curtains could reduce basal melting, but the study says constructing and installing them would be "extremely challenging," potentially exceeding ship transport capacities and altering ocean circulation. The authors warned that any changes to water flow could disrupt nutrient delivery to marine ecosystems and introduce pollution depending on materials used.

Proposals to increase surface reflectivity have included scattering hollow glass beads across sea ice to boost albedo, the fraction of solar energy reflected back to space. The paper cites estimates that roughly 360 million metric tons of glass beads per year would be required—about equal to the annual global production of plastic—and that such quantities pose significant logistical, production-emissions and ecological concerns. The beads could be mistaken for food by zooplankton and other small organisms, potentially introducing novel hazards into polar food webs.

Ocean fertilization, another contested idea, would add nutrients such as iron to upper ocean waters to stimulate phytoplankton growth and draw down atmospheric carbon dioxide. The authors said such interventions risk disrupting marine food webs, creating low-oxygen "dead zones," and increasing the frequency or extent of toxic algal blooms. They also questioned the scale needed for meaningful climate impact, noting the treated area would need to be many times larger than currently feasible and would require a fleet of specially adapted ships for deployment.

Relatively simpler-sounding mechanical approaches also drew scrutiny. Sea ice thickening schemes would pump seawater onto or above ice to freeze and add mass; earlier calculations suggest millions of wind-powered pumping units would be required to cover a meaningful fraction of the Arctic. The paper cited estimates that roughly 10 million pumps would be needed to cover 10 percent of the Arctic Ocean and 100 million for full coverage, numbers the authors said make the approach logistically infeasible. A proposal to slow ice by drilling into ice sheets to increase basal friction likewise raised concerns about contaminating subglacial ecosystems and the unprecedented scale of polar drilling operations that would be required.

Across these proposals, the researchers highlighted gaps in scientific understanding, weak evidence for long-term effectiveness, and the potential for unintended, irreversible consequences. They also underscored the risk of "termination shock"—a rapid, severe warming that could occur if a geoengineering program were abruptly halted, leaving the climate to readjust to greenhouse gas concentrations with little transition time.

The paper's authors emphasized that many of the polar geoengineering ideas are being promoted by a small number of groups and that some open-air solar radiation management experiments have already taken place. They urged caution and argued that the most effective and least risky path remains deep reductions in greenhouse gas emissions and rapid decarbonization of energy systems.

The Frontiers in Science publication follows an ongoing global debate about whether large-scale, intentional manipulation of Earth systems can or should be used to limit warming. Proponents of some techniques argue they could buy time while emissions cuts are implemented; critics say they risk distracting from mitigation and adaptation, carry transboundary environmental and governance challenges, and lack robust international regulatory frameworks. The authors of the new paper called for strengthened governance, rigorous risk assessment, transparent research, and prioritization of emission reductions over high-risk technological interventions.

Scientists participating in the briefing said their goal was to draw attention to the unique vulnerability and limited understanding of polar systems. They concluded that while research into the physical processes and consequences of geoengineering is necessary to inform policy, major polar deployments of the types reviewed are scientifically flawed, likely infeasible, and could cause lasting harm to ecosystems and global climate stability.