.ON APRIL 2ND a device being similar to a snow machine on the deck of the USS Hornet, a nonexistent aircraft-carrier anchored in San Francisco Gulf, started generating a mist of salty aerosol fragments. The clinical partnership behind the job, the Marine Cloud Whitening (MCB) programme, led due to the Educational institution of Washington, is examining whether such sprays might aid to slow down environment modification with a type of “geoengineering”. What performs this term method– and why is it thus disputable?