from guardian.co.uk: Two Harvard engineers are to spray sun-reflecting chemical particles into the atmosphere to artificially cool the planet, using a balloon flying 80,000 feet over Fort Sumner, New Mexico. The field experiment in solar geoengineering aims to ultimately create a technology to replicate the observed effects of volcanoes that spew sulphates into the stratosphere, using sulphate aerosols to bounce sunlight back to space and decrease the temperature of the Earth. David Keith, one of the investigators, has argued that solar geoengineering could be an inexpensive method to slow down global warming, but other scientists warn that it could have unpredictable, disastrous consequences for the Earth's weather systems and food supplies. Environmental groups fear that the push to make geoengineering a "plan B" for climate change will undermine efforts to reduce carbon emissions. Keith, who manages a multimillion dollar geoengineering research fund provided by Microsoft founder Bill Gates, previously commissioned a study by a US aerospace company that made the case for the feasibility of large-scale deployment of solar geoengineering technologies.