Can geoengineering put the freeze on " global warming " ?

Scientists call it "geoengineering," but in plain speak, it means things like this: blasting tons of sulfate particles into the sky to reflect sunlight away from Earth; filling the ocean with iron filings to grow plankton that will suck up carbon; even dimming sunlight with space shades.

Each brings its own set of risks, but in a world fretting about the consequences of global warming, are these ideas whose time has come?

With 2010 tying as the world's warmest year on record and efforts to slow greenhouse gas emissions looking stymied, calls are rising for research into engineering our way out of global warming — everything from launching solar shade spacecraft to genetically engineering green deserts. An international consortium of 12 universities and research institutes on Tuesday, for example, announced plans to pioneer large-scale "ocean fertilization" experiments aimed at using the sea to pull more greenhouse gases out of the sky.