Billionaire Bill Gates is backing an experimental plan by Harvard scientists to cool the earth - by dimming the sun's light.
The 'Stratospheric Controlled Perturbation Experiment', or SCoPEx, would spray sun-reflecting particles into the stratosphere, which scientists say could help offset global warming.
Bill Gates is one of the financial backers of SCoPEx, which has already launched over 300 test balloons and is planning to launch another over Sweden next year.
However, some environmentalists are opposed to the idea and are calling for a moratorium on so-called 'solar geoengineering'.
Planned Harvard balloon test stirs solar geoengineering unease