It's getting hotter
Whether it is man-caused or natural -- or a combination of the two, the planet is warming up. A new Universtiy of Arizona study reports that temperatures have been steadily rising over the past decade. "Nine of the 10 warmest years on record have occurred since 1995."

The UA study predicted that the Earth's temperatures would rise by at least 4 degrees by 2100. This would be "comparable to conditions 130,000 years ago when the ice sheets melted."