redOrbit: A poll of experts finds that a dramatic climate shift such as the death of the Amazon forest or the disappearance of Greenland’s ice is more than 50 percent likely during the next 200 years under the worst case global warming scenarios. The survey of 52 scientists also revealed concerns that long-term global warming would spur drastic changes such as the disintegration of the ice sheet in West Antarctica, something that would raise world sea levels. "There’s concern about the …