Overview

• An international assessment published in Frontiers in Science concludes five prominent ideas for cooling the poles would not pass scrutiny and could damage fragile ecosystems and international relations.
• The review examined stratospheric aerosol injection, underwater sea curtains, sea‑ice thickening or brightening, basal water removal, and ocean fertilisation, finding none has robust real‑world testing or viable governance pathways.
• Researchers estimate each concept would cost at least $10 billion to set up and maintain, with sea curtains projected at about $80 billion over a decade for an 80‑kilometre structure.
• The authors warn these proposals risk diverting money and political will from proven emissions cuts, noting particular hazards such as ozone impacts from aerosols, habitat disruption from curtains, and contamination or food‑web effects from other methods.
• The findings drew pushback from some scientists who call for continued trials, as the UK‑backed Cambridge team plans a small Arctic seawater‑pumping field test this winter and other efforts, such as glass‑bead sea‑ice work, have already been curtailed over ecological concerns.