The melting of the polar ice caps caused by climate change has potentially catastrophic impact beyond rising sea levels. A huge amount of solar energy is reflected back into space by these white expanses. Stephen Hawking predicted that the earth would have an atmosphere similar to Venus if we melted the ice caps. Most responses to global heating concentrate on renewable generation and, to a lesser extent, reduced consumption. We are embarking on mitigation for global warming targets that are very ambitious given the current trajectories. Our path to 1.5 degrees warming seems precarious at best and we don’t know if we have already entered feedback loops that will inexorably damage the polar ice caps. What if we could replicate the reflective effect of the polar ice caps without the need to remove CO2 from the atmosphere?

Stephen Salter is Emeritus Professor of Engineering Design at the University of Edinburgh and inventor of the eponymous Salter duck wave energy device. He is also a pioneering proponent of geoengineering, working on the engineering hardware for John Latham’s proposal to exploit the Twomey effect. 15 years ago he presented the concept of the mechanical enhancement of clouds to achieve greater cloud reflectivity to the Engineering Club in London. Now his work concentrates on nothing else. In this time the calculations have been worked through, the vessel designs refined and we have a greater understanding of the ocean current systems that drive our weather. Geoengineering is fraught with risk because of the scale and the need for a global political commitment. But is it time for engineers - indeed everyone - to give serious consideration to making marine cloud brightening possible?