John Wheeler: The Ice Age climate was very dry
The glaciers locked up a significant amount of Earth's water, and this caused many places to be very dry.
FARGO — The advance of glaciers during the Ice Age brought drastically different weather to the planet than today's weather. The glaciers locked up a significant amount of Earth's water, and this caused many places to be very dry. This gave rise to a biome known as the "Mammoth Steppe." It stretched from Spain all the way through Europe across Russia and into Alaska (then connected to Asia due to low sea level) and the Yukon before ending at the Laurentide Ice Sheet.
For tens of thousands of years, this region would have been quite arid and treeless, like an African savanna only very cold. Remnants of this biome do actually exist today in parts of Russia and Mongolia. Most of our region except west of the Missouri River and the "drift-less" area of southeastern Minnesota, northeastern Iowa, and southwestern Wisconsin were covered in the ice of the Wisconsin glacier, which extended into central and northern Canada.