Human intervention: help or hindrance?

http://www.wupr.org/2010/04/14/spin-till-you-win-chapter-2/20090831-climate-engineer/

In our rush to try to prevent severe climate change, scientists from the University of Reading have shown that one of the most credible methods, injecting reflective particles into the stratosphere, may have negative consequences for tropical rain forests.

The idea is that theses reflective particles should absorb and reflect incoming solar radiation, thus reducing that which reaches the planet and enters the greenhouse cycle inside our polluted atmosphere. The research team found that as well as absorbing heat coming in from the Sun, the particles also absorb some of the heat energy that comes from the surface of the planet. The heating this causes acts to stabilise this part of the atmosphere, but by making it more stable it reduces the upwelling of air in the  tropical overturning circulation. This then reduces the supply of warm moisture laden air that provides important rainfall, apparently reducing it by up to 30%.

However, others have questioned their findings, and the researchers admit that this was the most extreme model result in extreme warming scenarios. It seems that we can never know the true consequences of climate engineering until we try them for real. Have a read of the BBC report and the paper itself to find out more:

Matt McGrath, "Geoengineering plan could have 'unintended' side effect", http://www.bbc.co.uk/news/science-environment-25639343

Ferraro. A., J., E. J. Highwood and A. J. Charlton-Perez, (2014)"Weakened tropical circulation and reduced precipitation in response to geoengineering" Environmental Research Letters, 9, 1