Solar radiation modification : ethical perspectives

Abstract

This Opinion covers research into, prospective deployment of and governance models for one of the most widely discussed geoengineering methods: solar radiation modification (SRM), sometimes simply referred to as solar geoengineering or solar radiation management. SRM comprises all methods and tools that intentionally alter the Earth’s atmosphere or surface to reflect more sunlight back into space, reducing the amount of solar radiation reaching the Earth’s surface or allowing more infrared radiation to escape into space, seeking to create a net cooling effect on the climate. Specifically, the SRM toolbox includes: i. stratospheric aerosol injection (SAI) – the most studied form of SRM – which involves techniques such as injecting precursor gas sulphur dioxide (SO2) into the stratosphere, mimicking the effect of large volcanic eruptions; ii. cloud modification, which involves either brightening clouds (usually marine clouds), thinning high clouds (usually cirrus clouds) or seeding mixed-phase clouds; and iii. surface brightening (albedo engineering), which includes a range of techniques from urban and agricultural modifications such as changing rooftops or selecting crops that reflect the sunlight more than others, to covering desert areas with highly reflective materials or whitening oceans with small glass spheres, foams or microbubbles.