Pleistocene: how the last glacial era changed the world

The world has experienced multiple glacial eras throughout its history, with the most recent and prominent one being the Pleistocene epoch, which included multiple glaciations and interglacial periods.

Oct 26, 2023 - 18:34
Pleistocene: how the last glacial era changed the world
Image by Stefan Hoffmann / Pixabay

Our world has experienced several glacial eras, also known as ice ages, throughout its history. The term "glacial era" typically refers to periods of extended cold temperatures and the growth of large ice sheets and glaciers.

The most recent and well-known glacial era is the Pleistocene epoch, which spanned from about 26,500 to around 11,700 years ago. Global temperatures experienced significant fluctuations between colder glacial periods and warmer interglacial periods. The overall pattern was one of alternating ice ages and warmer phases.

During the Pleistocene epoch, there were multiple glaciations and interglacial periods, where ice sheets expanded and contracted. The most recent glaciation within the Pleistocene epoch is often referred to as the Last Glacial Maximum, which reached its peak around 20,000 years ago and began to recede around 11,700 years ago, marking the transition to the current interglacial period, known as the Holocene.

During glacial periods, large ice sheets extended over much of North America, Europe, and Asia. These ice sheets caused a reduction in global temperatures due to the reflection of sunlight by the ice, which is known as the albedo effect. Glacial periods were characterized by colder and drier conditions, with lower sea levels as a significant amount of water was stored in the ice sheets.

In contrast, during interglacial periods within the Pleistocene epoch, global temperatures rose, leading to the melting of ice sheets and the retreat of glaciers. These warmer phases were characterized by milder climates, higher sea levels due to the melting ice, and more favorable conditions for the growth of vegetation and the expansion of various ecosystems.

The fluctuations between glacial and interglacial periods during the Pleistocene were primarily driven by changes in Earth's orbit and axial tilt, known as Milankovitch cycles. These changes influenced the distribution of solar energy received by the planet, which in turn affected climate patterns and global temperatures.

So, while the Pleistocene epoch as a whole experienced both colder glacial periods and warmer interglacial periods, the overall pattern was one of temperature fluctuations rather than a continuous rise or fall.

While the Pleistocene epoch is the most recent and well-studied glacial era, there have been other glacial periods in Earth's history before the Pleistocene as well. These earlier periods are associated with different geological epochs and are often collectively referred to as "ice ages."

Valérie Tellier EA Global Coordinator