.ON APRIL 2ND a gizmo resembling a snowfall equipment on the deck of the USS Hornet, an obsolete aircraft-carrier anchored in San Francisco Gulf, began producing a haze of salty aerosol particles. The scientific collaboration behind the task, the Marine Cloud Brightening (MCB) program, led by the College of Washington, is looking into whether such aerosols might help to decrease temperature adjustment through a kind of "geoengineering". What does this phrase way-- and why is it thus questionable?