An ice age is the amount of the Earth's water that is locked up on land in the form of glaciers.
According to the scientists, an ice age occurs every 100,000 years. There are five major ice ages in the Earth's history. That are the Andean-Saharan, Huronian, Karoo Ice Age, Cryogenian, and the current Quaternary glaciation.
But, If we entered another ice age currently, it would increase the amount of locked water in the form of glaciers and hence it would have huge consequences for human civilization and the ecosystem.