.ON APRIL 2ND a gizmo resembling a snowfall equipment on the deck of the USS Hornet, a nonexistent aircraft-carrier anchored in San Francisco Gulf, began creating a haze of salty spray fragments. The clinical collaboration behind the project, the Marine Cloud Brightening (MCB) programme, led due to the University of Washington, is actually investigating whether such sprays might assist to slow down environment modification through a type of "geoengineering". What does this condition way-- and why is it thus disputable?