'Cheap' solar geoengineering plans may have unintended consequences


Attempts to control temperature by one country could affect precipitation levels in another, warn scientists

Researchers warn that individual countries looking to go it alone with 'cheap' solutions to regional climate change could inflict negative impacts on the rest of world

Large-scale 'geoengineering' interventions to alter the climate, such as increasing cloud cover to deflect solar radiation, may not work on a global scale, a new study has warned.

As climate change predictions worsen and international negotiations prove slow and unambitious, 'quick, techno-fix' solutions to alter the world's climate are gaining support.

However, an analysis of the most discussed technique - solar radiation management (SRM), which involves changing the amount of incoming energy from the sun by using aerosols to create clouds or deflecting solar rays with mirrors - says it could create a conflict of interest between countries.

The study, published in Nature Geoscience by researchers from Carnegie Mellon and Oxford Universities, says it may not possible to simultaneously control both temperature and precipitation levels with SRM. As such, attempts to reduce solar radiation in one region are likely to have knock-on effects in others.

A report by MPs from the Science and Technology Committee earlier this year contained similar warnings, saying SRM could produce 'droughts with severe implications for regional and global food production'.

'Cheap' solutions

The authors of this most recent study said as climate change impacts worsened individual countries might start unilaterally jumping on 'cheap' geoengineering solutions.

'Doing SRM is likely to be cheap,' said Professor Granger Morgan, head of Carnegie Mellon's Department of Engineering and Public Policy, 'so there is risk that a single nation or region might start doing it to solve a local or regional climate problem, and impose the impacts on all of us.'

The Met Office, which has recently created a new advice page on geoengineering, said it was too early to rule out the use of SRM and that it may still be possible to find a technique that concentrated the negative precipitation impacts over oceans and not land, where it can impact on food production.

'The [study] shows that it "may not be possible" to stabilise the climate in all regions simultaneously. I agree with their conclusions. But because they haven't tested all possible SRM scenarios, and because the results remain model-dependent to some extent, they can't say that it is definitely not possible,' said Dr Olivier Boucher, head of climate chemistry and ecosystems at the Met Office.

Focus on emission cuts

Study co-author Morgan said policymakers should focus more on reducing carbon dioxide emissions rather than geoengineering solutions.

'If the world doesn't get serious about achieving a dramatic reduction in emissions of carbon dioxide, the planet will have lost most of its coral reefs by the end of this century along with the fish and other marine life that they depend on,' said Morgan.

'We need to understand SRM but it is no substitute for finding ways to reduce carbon emissions by 80 percent as soon as possible.'

Useful links

Nature Geoscience study in full
Met Office guide to geoengineering

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