.ON APRIL 2ND a gizmo resembling a snow maker on the deck of the USS Hornet, a defunct aircraft-carrier moored in San Francisco Gulf, started producing a moisture of salted aerosol bits. The medical collaboration behind the task, the Marine Cloud Whitening (MCB) programme, led by the Educational institution of Washington, is exploring whether such sprays could aid to decrease environment change via a form of "geoengineering". What does this condition way-- as well as why is it therefore questionable?