This story omits key facts. In particular, the story omits data from Earth's more recent history--not 3,000,000 years ago or 122,000 years ago, but a mere 700 to 1,200 years ago. We know that much of the planet was warmer then, during our "Medieval Warming Period" and before the beginning of our "Little Ice Age." The average temperature, at least in the Northern Hemisphere, was approximately 1 degree Celsius warmer than it is today. Advocates of the theory that global warming is caused by human activity like to ignore that we have experienced previous periods of warming that had nothing to do with human emission of greenhouse gases. This bolsters their case that global warming will continue rather than reverse once again for reasons that are unclear. It fact that is exactly what is happening at present, since global warming peaked several years ago.