Approximately 18,000 years ago, the Earth was in the midst of the Last Glacial Maximum (LGM), which was the most recent period of extensive glacial advances during the Pleistocene epoch. During the LGM, there were multiple glacial advances and retreats, as glaciers expanded and contracted in response to changes in global climate.
The number of glacial advances during the Last Glacial Maximum can vary depending on the region and the specific definition of a glacial advance. Glacial advances occur when glaciers grow and advance beyond their previous positions, while glacial retreats happen when glaciers melt and move back. These advances and retreats can occur over various timescales and are influenced by complex interactions between temperature, precipitation, and other environmental factors.
In some regions, there may have been several glacial advances and retreats during the LGM, while in others, the glacial activity may have been more continuous. Additionally, some areas may have experienced multiple glacial advances at different times during the Last Glacial Maximum.
Overall, the Last Glacial Maximum was characterized by widespread glaciation, with ice covering large parts of North America, Europe, and Asia, as well as significant ice sheets in Antarctica. The exact number of glacial advances during this period is challenging to determine precisely, but it is clear that the Earth experienced significant glacial activity during this time.