Clive Hamilton has written another absorbing book on climate change. Unlike his previous works, which have focused on the causes and consequences of climate change, this latest book deals with the issue of geoengineering. This is the term used to cover all the different techno-fixes that have been suggested, either to reduce carbon dioxide in the atmosphere or, alternatively, to cool the planet by reducing the amount of sunlight that reaches the Earth. Geoengineering covers everything from the mad and the bad to the downright dangerous, although there are a few sensible suggestions that have been put forward as well.

Some, such as Robert Kunzig and Wallace Broecker in Fixing Climate, have argued that we need to install millions of artificial trees to absorb atmospheric carbon dioxide. We can then dump the trapped gas in exhausted oil and gas wells or at the bottom of the oceans. Others, such as