Geo-engineering schemes that aim to stabilize the Earth’s climate should be ranked according to their efficacy, cost, associated risks and timeframe, argues a Commentary online in Nature Geoscience. The author suggests that, of the various schemes that have been proposed, only a few can be investigated in detail and we must choose the most promising ones.

Philip Boyd makes a case that, given the urgency of combating global warming, timescale could be used as a knock-out criterion for geo-engineering schemes. The time it takes for climate stabilization measures to take effect, and the delay in halting a scheme if undesired side effects are overwhelming, have not received sufficient attention, according to Boyd. A transparent ranking process is needed in order to choose the best schemes, and to win public support.