LAMONT, Okla. — For decades, a small group of scientific dissenters has been trying to shoot holes in the prevailing science of climate change, offering one reason after another why the outlook simply must be wrong. Over time, nearly every one of their arguments has been knocked down by accumulating evidence, and polls say 97 percent of working climate scientists now see global warming as a serious risk. Yet in recent years, the climate change skeptics have seized on one last argument that cannot be so readily dismissed. Their theory is that clouds will save us. They acknowledge that the...