Geoengineering -- deliberate, large-scale interventions in the Earth’s climate system to counter the effects of global warming -- is now the subject of extensive research around the world. If nations seem unable to implement plan A, cutting greenhouse gas emissions, then, some believe, we must prepare plan B -- schemes such as fertilising the oceans so they soak up more carbon dioxide, brightening marine clouds so they reflect more sunlight, or coating the Earth with a solar shield of sulphate particles.

Although still in its early days, the constituency for geoengineering is now developing around a network of individuals with personal, institutional and financial links. At the centre of the network is a pair of North American scientists actively engaged in geoengineering research: David Keith and Ken Caldeira.