Climate Cooling Potential: Aerosols and Sunshades Lead the Race

  • Published on February 17th, 2009

ForestThe University of East Anglia (UK) has been conducting research into the likely potential of a range of geo-engineering schemes. These are processes that are designed to help combat global warming, and while some of the ideas seem wild, others are prosaic enough to please the hardest-headed climate change doubter. But what is their true potential in slowing, stopping or reversing the effects of climate change?

Slow and safe versus fast and frightening

Among their findings, the team of researchers suggests that enhancing existing carbon sinks is useful, but that their contribution would mean it would still take nearly a century to get atmospheric carbon dioxide levels back to pre-industrial levels – and that assumes that we continue to make deep emission cuts.

On the other hand, the Star Wars type proposals for gigantic space-located sunshades or aerosol injections into the stratosphere to restore the ozone layer are considered to be both the most likely activities to cool the climate by 2050 but carry the highest risk of something going wrong. In a week when nuclear submarines have collided in the deep ocean and satellites have done the same in space, this kind of project needs to be viewed not just for its short term climate efficacy but its long term potential to cause other problems with maintenance, disposal or unanticipated side-effects.

In the short term, bio-char (adding back charcoal from suitable organic materials to the soil) and forest planting have better potential in the short term for carbon sequestration than ocean-based projects that would help fertilise the world’s seas by boosting their phosphorous levels.

Geo-engineering part of the solution but not an answer to the problem

The team says that many geo-engineering proposals have been over-optimistic in calculating their benefits: such projects as bouncing back heat from urban areas by increasing their reflectivity, piping cold ocean water through coastal urban areas to reduce temperature and biological cloud-seeding to increase cloud reflectivity are all likely to be less effective on the global scale than was previously thought.

Their overall conclusion is stark – some geo-engineering projects will work well with climate change mitigation schemes, but cannot solve any part of the problem on their own.

Image: respres at flickr under a creative commons licence

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  • […] Bio-char is a finely-grained charcoal-like substance made from plant waste. It is highly resistant to decomposition and produced via the carbon neutral process of pyrolysis  or carbonisation, which is the ancient technique used to produce charcoal – the modern version heats organic waste airtight metal vessel to reduce pollution and condense volatile by-products like gases which would otherwise escape into the atmosphere, and the bio-energy produced can be converted to electricity, as well as producing and conserving ethanol and methanol. […]

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