RedOrbit: If we had a second Earth, we could experiment with its atmosphere to see how increased levels of greenhouse gases would change it, without the risks that come with performing such an experiment. Since we dont, scientists use global climate models. In the virtual Earths of the models, interlocking mathematical equations take the place of our planets atmosphere, water, land and ice. Supercomputers do the math that keeps these virtual worlds turning as many as 100 billion calculations for one modeled...