Geoengineering schemes, such as brightening clouds, are being talked about ever more widely. In the third of three features, Oliver Morton looks at how likely they are to work.

Without a solid commitment from the world

Plans to cool the planet by creating a sunshade could cut the amount of electricity generated by solar power.

One point repeatedly made at last week's climate change congress in Copenhagen was that formulating an action plan to curb climate change is not the job of scientists. (Editorial)

We may soon have no choice but to fiddle more directly with the climate

Once written off as sci-fi fantasy, geoengineering now looks like the last best hope to avert harmful climate change. (Editorial)