Geo-engineering not a "silver bullet", says Royal Society

Geo-engineering solutions are not a "silver bullet" for solving climate change and could have unintended environmental and social effects, according to a report from the Royal Society.

Nevertheless, the long-awaited report argues that governments should fund research in the area and calls on the UK to provide £10m a year to support the development of geo-engineering projects that could be used if efforts to curb carbon emissions fail.

The UK government currently provides no funding for geo-engineering, although climate change minister Joan Ruddick has said the technology represents a potential "plan B" for tackling global warming.

Martin Rees, president of the Royal Society, counselled that geo-engineering projects were at a very early stage of development and warned that more research would be required to identify the most effective proposals.

"Some schemes are manifestly far fetched; others are more credible, and are being investigated by reputable scientists; some are being promoted over-optimistically," he observed. "Far more detailed study would be needed before any method could even be seriously considered for deployment on the requisite international scale."

The report concludes that deliberately altering the Earth's climate is likely to be technically possible, but warns the required technology is barely formed, and that there are huge risks regarding its effectiveness, costs, and environmental impacts.

The Royal Society identified two main geo-engineering methods: carbon dioxide removal techniques designed to remove CO2 from the atmosphere, and solar radiation management (SRM) technologies which could reflect a small percentage of the sun's heat back into space.

The report says that in most respects carbon dioxide removal methods are preferable because they return the climate system closer to its natural state, and so involve fewer uncertainties and risks. They would also help mitigate the effect of increased CO2 concentrations on ocean acidification.

But of all the carbon dioxide removal methods assessed by the Royal Society, none has yet been demonstrated to be effective at an affordable cost with acceptable side effects. Moreover, any such solution is likely to take decades to have a measurable impact on the climate.

SRM methods work more quickly and should be the subject of further research in case rapid intervention is needed, the report says. But it also counsels that they should only be used for a limited period of time in case they have an unexpected impact on the climate.

It concluded that of the SRM methods considered, stratospheric aerosols are currently the most promising because their effects would be more uniformly distributed than other techniques, they could be implemented more readily than space-based methods, and would deliver a quantifiable effect within a year or two of deployment.

However, the report accepts that much more needs to be known about the environmental effects and social consequences of such projects before any large-scale experiments are undertaken.

The report also suggests that a world body such as the UN should co-ordinate a global effort to set governance frameworks to guide both geo-engineering research and development projects in the short term and possible deployment in the longer term.

In addition, it recommends that the Royal Society work in collaboration with international science partners to develop a code of practice for geo-engineering research.

However, green groups remain highly sceptical of geo-engineering proposals, arguing that they could have unknown consequences for the climate and serve to undermine efforts to cut carbon emissions.

Mike Childs, Friends of the Earth's head of climate change, said governments must be wary of viewing geo-engineering as a solution to climate change. "The different options will take time to develop, risks need to be properly researched, and if we use geo-engineering at all, it must be in addition to making deep cuts in the amount of carbon dioxide we produce in the first place, " he said.