(AP) -- If the sun warms the Earth too dangerously, the time may come to draw the shade. The "shade" would be a layer of pollution deliberately spewed into the atmosphere to help cool the planet. This over-the-top idea comes from prominent scientists, among them a Nobel laureate. The reaction here at the U.N. conference on climate change is a mix of caution, curiosity and some resignation to such "massive and drastic" operations, as the chief U.N. climatologist describes them.