Measurements of pressure on fixed structures are reviewed including the Helsinki and JOIA test programmes. The Molikpaq experience and the Hans Island programmes are described in some detail. Loads tend to be concentrated in small areas, as was the case for ship structures (the high-pressure zones). Size effect of ice pressure with regard to ice thickness is discussed; average pressures decrease with ice thickness. The medium scale field indentation programmes are described, covering the Pond Inlet, Rae Point, and Hobsons Choice Ice Island test series. Ice-induced vibrations are introduced; these were observed in the Molikpaq structure and in many indentation tests. The vibrations tended to occur at certain speed ranges, associated with ice crushing. Results of field tests on iceberg failure are also reviewed, in which supporting evidence for layer failure was obtained.

On the SRM side of the toolbox, we are at an even earlier stage, so the go-forward imperative here is not development but simply research. We need a much more sound understanding as to whether and how these interventions might work and how we might domesticate them via thoughtful and inclusive governance. The SRM sibling to the National Academies report described above was issued in spring 2021. It recommends an expenditure of $100–200 million over five years, a small fraction of the proposed budget for CDR. Nonetheless, this would be a vast expansion of resources for the field. My personal path forward entails working with colleagues to design aircraft that could be useful in such research.