redOrbit: Global warming, some have argued, can be reversed with a large-scale “geoengineering” fix, such as having a giant blimp spray liquefied sulfur dioxide in the stratosphere or building tens of millions of chemical filter systems in the atmosphere to filter out carbon dioxide. But Richard Turco, a professor in the UCLA Department of Atmospheric and Oceanic Sciences and a member and founding director of UCLA’s Institute of the Environment, sees no evidence that such technological …