.ON APRIL 2ND a device being similar to a snowfall maker on the deck of the USS Hornet, an inoperative aircraft-carrier anchored in San Francisco Bay, started generating a mist of salty aerosol particles. The scientific collaboration behind the job, the Marine Cloud Brightening (MCB) program, led due to the University of Washington, is actually investigating whether such sprays could assist to slow down climate adjustment through a form of "geoengineering". What performs this phrase mean-- as well as why is it thus disputable?