.ON APRIL 2ND a device being similar to a snowfall machine on the deck of the USS Hornet, a nonexistent aircraft-carrier tied in San Francisco Gulf, began producing a moisture of salted spray particles. The medical cooperation behind the project, the Marine Cloud Whitening (MCB) programme, led by the College of Washington, is actually exploring whether such aerosols may help to slow environment adjustment by means of a type of “geoengineering”. What performs this term mean– and why is it so controversial?