.ON APRIL 2ND a contraption appearing like a snowfall machine on the deck of the USS Hornet, an obsolete aircraft-carrier moored in San Francisco Bay, began making a mist of salty aerosol bits. The clinical partnership behind the job, the Marine Cloud Brightening (MCB) program, led due to the Educational institution of Washington, is actually investigating whether such aerosols may aid to reduce environment modification via a form of "geoengineering". What performs this condition method-- and also why is it therefore disputable?