.ON APRIL 2ND a device looking like a snowfall machine on the deck of the USS Hornet, a defunct aircraft-carrier tied in San Francisco Bay, started creating a moisture of salty aerosol bits. The clinical partnership behind the venture, the Marine Cloud Brightening (MCB) program, led due to the University of Washington, is looking into whether such sprays may aid to reduce temperature modification by means of a type of “geoengineering”. What does this condition way– as well as why is it thus controversial?