Spraying aerosols into the atmosphere may be fraught with risk, but to dismiss it out of hand is irresponsible, a climate scientist argues
Gernot Wagner has spent a large part of his life thinking about solar geoengineering, and even he thinks it is “nuts”, as he says in the first line of his book. Geoengineering is usually defined as large-scale interventions in our climate. Here, although Wagner refers briefly to carbon removal and natural climate solutions such as tree-planting, he is mainly concerned with solar geoengineering (also called solar radiation management), where aerosols would be deployed into the stratosphere to reflect sunlight back into space and reduce the amount of heat coming in. The comparison he returns to most often is that of the ash from a volcanic explosion.
It is a concept that has been around since the 1960s, when scientists first warned politicians about the possibility of global heating. But as evidence piled up that this warming really was happening, there was concern that geoengineering would seem like a cheap fix, and would distract people from the serious business of cutting carbon emissions. For this reason, Wagner writes, there was a “long‑standing, self-imposed, unspoken near-moratorium on solar geoengineering research within the scientific community”.