.ON APRIL 2ND a device resembling a snowfall machine on the deck of the USS Hornet, an invalid aircraft-carrier moored in San Francisco Gulf, began creating a haze of salty aerosol fragments. The medical collaboration responsible for the venture, the Marine Cloud Whitening (MCB) program, led by the Educational institution of Washington, is checking out whether such aerosols might help to reduce environment change via a type of “geoengineering”. What performs this term mean– as well as why is it therefore debatable?