.ON APRIL 2ND a contraption being similar to a snowfall machine on the deck of the USS Hornet, a nonexistent aircraft-carrier moored in San Francisco Gulf, started generating a mist of salted spray fragments. The scientific cooperation behind the project, the Marine Cloud Whitening (MCB) program, led by the University of Washington, is actually examining whether such aerosols could assist to slow environment change by means of a form of “geoengineering”. What does this condition way– and why is it thus debatable?