Stephen Salter Obituary

Stephen Salter was a South African-born Scottish academic who pioneered research in solar geoengineering. As Professor of Engineering Design at the University of Edinburgh, he became famous for designing the Salter Duck in response the oil shortage of the 1970s. It was a device that converts wave power into electricity. Waves make gyroscopes rotate in the pear-shaped “duck,” and an electrical generator converts this rotation into electricity with an overall efficiency of up to 90%.

Salter’s final decades were devoted to designing nozzles and ships for Marine Cloud Brightening (MCB). Stephen and a number of other scientists collaborated with John Latham in writing a 2012 article that introduced the idea of spraying tiny particles of sea salt into clouds. Since tiny droplets are whiter than large ones, this addition brightens each cloud slightly, increasing its reflectivity (albedo), and thus cools the water below. This cannot eliminate the whole problem of climate change, but it would cool the planet somewhat and to give humankind a little more time to reduce the greenhouse gases in the atmosphere.

Stephen was deeply concerned about the climate and frequently appeared on forums that Project Save the World hosts where experts discuss glob- al threats. He pointed out that MCB would not only potentially refreeze the Arctic but even reduce the intensity of hurricanes.

In 2023 he purchased a 3000 m2 engineering workshop to establish the Lothian School of Engineering, where Stephen wanted to construct a spray tunnel to test wafer nozzle designs. He also established a new organization to own the Lothian School and carry on his work posthumously.

As with many bold innovators, Stephen received both high recognition and scorn for his originality. He was appointed a Member of the Order of the British Empire (MBE) in the 2004 for services to engineering. Yet he was also treated as a pariah by the most promient climate change researchers, for, as Robin Collins notes in his current controversy column in this issue, marine cloud brightening is a form of geoengineering, and opinions have been deeply divided until recently about that way of cooling the planet.

Yet Marine Brightening has been recently endorsed by Dr James Hansen et al in their article Global Warming in the Pipeline as the promising and safest method of solar radiation management. Perhaps the tide is turning. Well done, Stephen