The Pleistocene, popularly known as the Ice Age, is the geological epoch that lasted from about 2.58 million to 11,700 years ago. It was followed by the Holocene, the epoch we live in today. Together, the Pleistocene and the Holocene make up the Quaternary Period, the most recent chapter of Earth’s history.

The Pleistocene saw a series of glaciations: periods of markedly colder climate when the ice sheets of Earth’s polar regions were far more extensive than they are today. These glaciations have different names in different regions. The most recent, for example, is known as the Vistulian (or Weichselian) in northern Europe, the Würm in the Alps and the Wisconsin in North America. The Vistulian glaciation – named after the Vistula River – lasted from about 115,000 to 11,700 years ago. Its end is taken to mark both the close of the Pleistocene and the beginning of the Holocene.

These glacial periods were separated by intervals of relatively warmer climate, called interglacials. The last of these within the Pleistocene, the Eemian interglacial, lasted from about 130,000 to 115,000 years ago.

Although the retreat of the last ice sheets marks the start of the Holocene as a separate geological epoch, the glacial–interglacial cycle characteristic of the Quaternary is thought to be continuing. On this view, the present warm period is an interglacial phase which, in the natural course of the cycle, could be followed by another period of severe cooling and the advance of ice sheets. The Holocene can therefore be seen as simply the latest interglacial in a long series stretching back through the Quaternary.

Without human influence, the next glaciation would probably naturally begin in about 50,000 years’ time, driven mainly by cyclical changes in Earth’s orbit. Human carbon dioxide emissions, however, could delay its onset by tens of thousands of years – and if concentrations remain high, by even 100,000 years or more.