.ON APRIL 2ND a device appearing like a snow equipment on the deck of the USS Hornet, an obsolete aircraft-carrier tied in San Francisco Gulf, started producing a mist of salted aerosol fragments. The clinical cooperation behind the project, the Marine Cloud Whitening (MCB) programme, led due to the College of Washington, is checking out whether such aerosols may aid to slow climate modification by means of a type of "geoengineering". What performs this phrase mean-- as well as why is it thus disputable?