lkypnk writes, "The AP is reporting that Nobel Prize winning scientist Paul Crutzen has suggested deliberately spreading a layer of particulate matter in the upper atmosphere to help reflect some of the sun's energy in an effort to combat global warming. He reminds us that the eruption of the volcano Pinatubo in 1991 cooled the planet by as much as 0.9 degrees; he believes his computer simulations show a similar effect from deliberate injection of sulfur into the atmosphere by humans. Whatever the feasibility of the idea, as the president of the National Environmental Trust has said, 'We are already engaged in an uncontrolled experiment by injecting greenhouse gases into the atmosphere.'" From the article: "'It was meant to startle the policy makers,' said [Crutzen]. 'If they don't take action much more strongly than they have in the past, then in the end we have to do experiments like this.' ... Serious people are taking Crutzen's idea seriously."