It's so obvious, it's a wonder nobody thought of it before: releasing vast quantities of sulphuric acid into the atmosphere to save - yes, save - the planet.
An alternative, says University of Calgary climate scientist Dr David Keith, is to use levitating nano-sized disks instead.
Geoengineers investigating ways of cutting global warming have tended to focus on injecting sulphur dioxide into the upper atmosphere. This imitates the way volcanoes create sulphuric acid aerosols, or sulphates, that could reflect solar radiation back into space.
Releasing sulphuric acid, or another condensable vapour, from aircraft would give better control of particle size, says Keith. This would allow more solar radiation to be reflected back into space, while using fewer particles overall and reducing unwanted heating in the lower stratosphere, he says.
He also describes a new class of engineered nano-particles that he reckons could offset global warming more efficiently and with fewer negative side-effects than sulphates.
Keith concedes that geoengineering is, to say the least, controlversial.
"A downside of both these new ideas is they would do something that nature has never seen before. It’s easier to think of new ideas than to understand their effectiveness and environmental risks," he admits.
"Geoengineering is inherently imperfect. It cannot offset the risks that come from increased carbon dioxide in the atmosphere. If we don’t halt man-made CO2 emissions, no amount of climate engineering can eliminate the problems — massive emissions reductions are still necessary.”