.ON APRIL 2ND a device looking like a snowfall equipment on the deck of the USS Hornet, a nonexistent aircraft-carrier tied in San Francisco Gulf, started making a moisture of salted aerosol bits. The clinical cooperation behind the job, the Marine Cloud Whitening (MCB) programme, led due to the University of Washington, is actually examining whether such sprays might aid to slow environment improvement with a kind of “geoengineering”. What does this phrase mean– and also why is it therefore disputable?