It’s estimated that the time period known as the Ice Age occurred nearly two million years ago. During the Ice Age, the most recent episodes of global cooling took place. Many of the earth’s temperate zones were alternately covered by glaciers during cool periods and uncovered during warmer interglacial periods when glaciers retreated.
If you think the odds of a second Ice Age are slim to none, you’re wrong. Jen Bischof, research assistant professor in the department of Ocean, Earth and Atmospheric Sciences at Old Dominion University and the author of Ice Drift, Ocean Circulation and Climate Change, believes a new ice age is coming.

INsider: So what exactly is the Ice Age?
Bischof: You can call the entire last 1.6 million years the ice age. It has been consistently cold with intermittent warm periods, such as the one we are currently living in.

IN: Really?
JB: Yes. It’s important to note that of the last 1.6 million years, only 10 percent were as warm as today and 90 percent of the time it was not only much colder in general, but large parts of the northern hemisphere land masses were buried under huge ice shields.

IN: How did the ice age come about?
JB: There are a variety of factors. The primary drivers of changing temperatures on earth are the so-called Milankovitch cycles. The principle is that the earth does not always rotate around the sun the same way. Its orbit becomes more elliptical from time to time, the tilt of its rotational axis changes with respect to the plane around the sun, and the North Pole of the earth’s axis moves in cycles, completing one turn every 23,000 years. The changes in the earth’s rotation cause changes in the amount of solar radiation received by the earth, and this causes temperature changes. The timing of these changes is precisely known and coincides with the ice age cyclically.
It’s important to understand that ice ages form slowly, most likely in the farthest northern and southern lands, at great altitudes, where even in the midst of summer temperatures rarely rise above zero. The gradual accumulation of snow makes the ice grow, and in turn the resulting "whiteness" in the high latitudes leads to an increasing albedo.

IN: What does that mean?
JB: That means incoming radiation is reflected and not converted into heat, amplifying the cooling trend. Only at their very last, after thousands of years of buildup, do ice ages reach their maximum extent.

IN: What were the effects of the last ice age on the earth?
JB: There is no such thing [as] a negative or a positive. It depends on your viewpoint. For example, for the mammoths, the ice ages were a boon. The cold climate suited them just fine. For early humans it was fine, too, because they ate mammoth meat and wore [mammoth] hides. The last ice age quite possibly gave rise to the advent of modern humans, which arrived in central Europe (now France) about 35,000 years ago. Because of the cold conditions, humans had to adapt and become inventive.

IN: Will a second ice age do to the earth?
JB: What will it do? It’s impossible to tell, particularly because any such cooling trend could be completely offset by the human-induced greenhouse effect.

IN: Can the second coming of the ice age be prevented?
JB: There is nothing anyone can do about it. The next ice age could, in fact, be under way. Ice ages build up slowly and we may be in that growth phase. When you look at ice sheets and glaciers of Svalbard, Franz Josef Land and other areas around the Arctic, they are young, new formations, in some cases only 2,000 years old.
In addition, there is no doubt that the man-made gas emissions into our atmosphere will cause changes in the climate, but we just don’t know what these changes will be like. What I am saying is that we can not afford to ignore that there are underlying, naturally occurring climate cycles as well.