I saw a study done about global warming and the climactic changes in the history of the Earth and IF we do go into an Ice Age again, its likely that it is part of the NATURAL processes of Earth's climactic cycle. For a while now scientists have believed that we are in a warm period of an Ice Age but are in fact still IN an Ice Age. When the global converyor belt (the Oceanic Current system) is shut down which it is want to do every so often in a natural cycle, the ice age cometh.
Ice Ages aren't exactly a bad thing. THe last ice age spurred the growth of human technological advancements in Europe far faster than in other parts of the world. New tools, techniques for adapting to cold weather living and shelters were developed to cope with the cold weather. Will it hurt the global economy? Certainly it will but there is little to NOTHING we can do about it since it is part of the NATURAL cycle of Earth's weather.
For my source I quote The Discovery networks which are owned by the very liberal BBC. They step by step went through the historical evidence of the shift between warm periods and Ice Ages and found the correlation to be STRIKINGLY similar to the current pattern of global weather changes occuring right now. The temperature will go up slowly for a period of time and then within a short time following the Ice Age comes. Now I cant say if any or all of it is true because this is just what I saw on the program and I didnt do the research myself so take it how you will but the brightest scientists in their field gave the report so I tend to believe it.