Don Bogard, isotopic and nuclear geochemistry: Today, when many are concerned about the Earth possibly over-heating through greenhouse warming, it is worthwhile to look into the not very distant past when the Earth over-cooled. Most people have heard of the Ice Age but probably know very little about it. Some may remember climate scientists in the 1970s expressing concern that Earth may be entering a new ice age, because of growing evidence that Earth was cooling (in spite of growing atmospheric carbon dioxide of CO2). What was the ice age, why did it occur, and is it now in our past, or also in our future?
