Overview

• Published in Frontiers in Science, the assessment led by Prof Martin Siegert evaluates five prominent proposals and concludes none pass scrutiny.
• The reviewed concepts include stratospheric aerosol injection, underwater sea curtains, sea‑ice thickening or albedo tweaks, basal water removal, and ocean fertilisation.
• Authors cite environmental dangers such as ozone depletion, disrupted marine habitats and migration routes, contamination of subglacial environments, and altered ocean chemistry.
• Estimated costs start at roughly US$10 billion per project, with sea curtains projected at about US$80 billion over 10 years for an ~80 km installation.
• Governance gaps persist for key methods like aerosol injection and sea‑ice management, and the paper warns these efforts could undercut emissions cuts even as some UK‑funded teams plan limited Arctic field trials.