.ON APRIL 2ND a device resembling a snow machine on the deck of the USS Hornet, an inoperative aircraft-carrier moored in San Francisco Gulf, began creating a moisture of salty spray particles. The medical collaboration responsible for the task, the Marine Cloud Brightening (MCB) program, led due to the Educational institution of Washington, is actually examining whether such aerosols could help to slow temperature change with a type of "geoengineering". What performs this term method-- and also why is it so debatable?