Geo-engineering: not a catch-all solution to climate change

New research from scientists at the University of East Anglia suggests that large-scale geo-engineering projects are not a viable alternative to carbon reduction strategies in the fight against global warming. However, the researchers conclude that certain geo-engineering schemes could compliment activities aimed at reducing greenhouse gas emissions.

The researchers examined a number of geo-engineering proposals, calculating their potential to cool the planet to pre-industrial levels by 2050. Those schemes with the largest cooling potential were sunshades in space and the injection of aerosols into the stratosphere – 10 – 50 km above the Earth’s surface.

Despite the potential for sunshades and aerosols to be used, the continual increase of carbon dioxide in the atmosphere would call for the constant addition of aerosols or areas of sunshades to counteract this. In the case of sunshades, 4 million square km would have to be launched into space initially, followed by 31,000 square km each year thereafter, to keep pace with continual carbon emissions at current rates.

Researchers suggest that schemes to remove carbon dioxide from the atmosphere are more realistic, and less risky. Seeding the oceans with iron or phosphorus fertiliser were predicted to have little or no effect on cooling, and with a damaging effect on marine wildlife. Similarly, biological pumps, bringing nutrient rich water from the deep to the surface oceans, to be used by organisms to produce more carbon, would have little impact. However, the researchers suggest that planting a large area of forest, producing charcoal and burying it in the soil as ‘biochar’ and the application of carbon and capture and storage technology to biofuels could reduce the temperature to pre-industrial levels by 2300.

Overall, the researchers conclude that no one geo-engineering scheme can be successful on its own, and no combination of schemes can be adopted in the absence of measures to curtail the carbon emissions we produce.

Original text from: Science for Environment Policy

Lenton, T.M. and Vaughan, N.E. (2009). The radiative forcing potential of different climate geoengineering options. Atmospheric Chemistry and Physics Discussions. 9:2559-2608.