Solar shield on agenda at climate summit

Emergency measures to slow global warming, such as a ‘solar shield’ to block the sun or artificial trees to soak up CO2, will be discussed at a ‘geo-engineering’ conference.

By Alastair JamiesonPublished: 9:19AM GMT 13 Jan 2010

The summit of climate scientists, to be held in California in March, will examine drastic techniques for slowing climate change that are controversial and have been described as “geo-piracy”.
Among the possible measures to be discussed will be ocean fertilisation, which would see iron dumped into the sea to boost plankton growth, and artificial trees that use a chemical process to soak up CO2.

Most techniques focus on ways of reducing the sun’s rays by blocking them using mirrors orbiting in space or by spraying sulphur compounds into the high atmosphere to reflect sunlight away from earth.
One proposal is for a fleet of ships that would spray seawater into the sky that would leave behind salt crystals to brighten clouds, reflecting more sunlight back into space.
The conference, reported in The Guardian, comes amid concern that such techniques may be the only way to prevent average temperatures rising.
Mike MacCracken, a global warming expert at the Climate Institute in Washington DC, who is organising the conference's scientific programme, told the newspaper: "Most of the talk about these geo-engineering techniques say they should be saved until we get to an emergency situation. Well, the people of the Arctic might say they are in an emergency situation now."
Scientists at the Department for Environment, Food and Rural Affairs say the techniques should not be ruled out but that more evidence from experiments is required.
The Swedish Society for Nature Conservation recently described geo-engineering an act of "geo-piracy" and warned that the "the world runs a serious risk of choosing solutions that turn out to be new global problems".
However, some geo-engineering techniques are already being used on a large scale. The Chinese government is thought to use cloud-seeding on a regular basis to encourage precipitation in areas hit by drought.