.ON APRIL 2ND a device being similar to a snow equipment on the deck of the USS Hornet, a defunct aircraft-carrier tied in San Francisco Bay, began generating a mist of salted aerosol particles. The medical cooperation responsible for the project, the Marine Cloud Whitening (MCB) programme, led by the Educational institution of Washington, is checking out whether such sprays may assist to reduce temperature improvement through a form of "geoengineering". What does this term method-- and why is it therefore questionable?