.ON APRIL 2ND a contraption resembling a snowfall device on the deck of the USS Hornet, an invalid aircraft-carrier moored in San Francisco Gulf, started generating a mist of salty aerosol particles. The clinical collaboration responsible for the project, the Marine Cloud Brightening (MCB) programme, led by the College of Washington, is actually examining whether such sprays may help to reduce climate improvement via a form of “geoengineering”. What performs this phrase method– and also why is it therefore questionable?