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 don’t, scientists use global climate models.
In the virtual Earths of the models, interlocking mathematical equations take the place of our planet’s atmosphere, water, land and ice. Supercomputers do the math that keeps these virtual worlds turning — as many as 100 billion calculations for one modeled year in a typical experiment. Groups that project the future of our planet use input from about 30 such climate models, run by governments and organizations worldwide. (more…)