A Terrifying GIF Of An Ice Age Ripping Through The US Leslie BaehrMay 15, 2014, 12:38 PM The northern ice cap creeps over earth. As we watch glaciers around the world recede, we sometimes hear the argument that these changes are part of the Earth's natural fluctuation. To some extent, they are. We've been in a relatively stable and warm period for at least 15,000 years. And we are unnaturally making the Earth even warmer. Before that, ice ages covered most of the Northern Hemisphere with glaciers. The last of the five major ice ages, called the Pleistocene glaciation, began...