A major new assessment examined five of the leading ideas for their effectiveness, feasibility, risks, costs, and governance. But they concluded that none passed scrutiny and all would be environmentally dangerous.

Take the seabed curtain concept, proposed to slow glaciers like Thwaites in Antarctica. Diverting warm water from one glacier might simply accelerate melting elsewhere. And a case study for Greenland's largest marine-terminating glacier found that artificial barriers would likely harm marine productivity, with serious consequences for local fisheries that must be weighed alongside any technical questions.

Perhaps the biggest danger isn't technical, it's political. Geoengineering could be used by bad actors as a strategy to create the illusion of a climate solution without committing to decarbonisation. Cost estimates for polar geoengineering run into the trillions, well above the estimated cost of emissions mitigation and adaptation, which carry far more co-benefits. It is widely agreed that the most effective long-term approach to slowing glacier and ice sheet melt is to cut emissions.

@glacierwatch
Thanks for this - answering some questions raised by #Ministryforthefuture