.ON APRIL 2ND a gizmo being similar to a snowfall maker on the deck of the USS Hornet, a nonexistent aircraft-carrier anchored in San Francisco Bay, began creating a mist of salted aerosol fragments. The clinical cooperation responsible for the venture, the Marine Cloud Brightening (MCB) programme, led due to the Educational institution of Washington, is checking out whether such sprays may aid to reduce weather change by means of a kind of “geoengineering”. What does this phrase way– and why is it therefore questionable?