.ON APRIL 2ND a gizmo being similar to a snow device on the deck of the USS Hornet, an invalid aircraft-carrier moored in San Francisco Bay, started making a moisture of salty spray particles. The scientific partnership responsible for the job, the Marine Cloud Brightening (MCB) programme, led by the Educational institution of Washington, is actually investigating whether such sprays may aid to decrease climate improvement via a kind of "geoengineering". What does this phrase way-- as well as why is it therefore controversial?