Scientists are saying there's a 9 out of 10 chance that the global average temperature will rise by 3 to 9 degrees Fahrenheit over the next century, and a 4 to 6 degree increase is the most likely scenario. The scientists are reporting on a new probability analysis. The most likely projected increase is five times the one-degree temperature rise observed over the past century. By as early as 2030 the planet is likely to heat up by a degree or two, the scientists say. The study is published in the July 20 issue of the journal Science.