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.