An ice age is a long period of time when the whole earth is much colder than usual. Some scientists speak of an ice age when at least one pole of the earth is glaciated. Then there is always ice. Other scientists find that both poles of the earth must be glaciated. Because today the Arctic and Antarctic are under ice, we live in an ice age.
Planet Earth is about four and a half billion years old. A billion is made up of 1000 million. In this long history of the earth, there have been at least five ice ages. In such an ice age it is usually cold. But there are also some times when it is significantly warmer. The cold period in the ice age is called glacial, and the warm period is interglacial. So the interglacial period is between the glacial periods.
Today we live in a geological age called the Quaternary. This quaternary started two and a half million years ago. The Quaternary is an ice age. However, it has cold periods and warm periods. Earth has been in the Holocene for about 11,700 years. This is a warm period. So we live in a warm period in an ice age.
What does the earth look like during an ice age?
When one speaks of the “Ice Age” today, one is probably thinking of the time before our interglacial period: the “last cold period”. Even then, for example, the North Pole was covered by ice, as it is today. But the ice went much further south. Half of Germany was under ice at the time.
Much of the ice was made of water that came from the seas. As a result, less water was left for the seas: the sea level was lower than it is today. That was about 110 meters in Europe.
When the sea is lower, some areas that are now submerged remain on the land. An example is the North Sea: Large parts of this sea were simply land during the Ice Age. Stone Age people lived there. The British Isles were not islands at all, but part of the mainland.
It was colder in Europe and North America. People had to dress warmly or tended to stay in the south. But at that time there were many large mammals, such as mammoths and large cattle. You could hunt them. In the Holocene, our interglacial period, many large mammals became extinct. Researchers today are not sure whether this was caused by nature or whether humans were to blame.