How did glacial and interglacial cycles during the Quaternary change sea level and environments?

During the Quaternary Period, the Earth experienced repeated cycles of glaciation and interglaciation, which profoundly altered global environments and sea level.21

Sea Level Fluctuations

Glacial periods involved the transfer of massive volumes of water from the oceans to continental ice sheets, causing sea levels to drop significantly—by as much as 100 metres (about 300 feet). Conversely, during interglacial periods, the melting of these ice sheets led to a "glacioeustatic" transgression, where rising seas flooded continental shelves and coastal regions. This process created distinct geological features, such as erosional terraces and beach deposits, and forced the migration of coastal environments.234

Environmental Changes

The expansion of ice sheets into temperate latitudes fundamentally reshaped the landscape and climate:5
* Atmospheric Impact: High ice sheets and cold air domes displaced polar jet streams, steering storms toward glacial margins and creating strong, drying katabatic winds.5
* Terrestrial Shifts: Areas near glaciers developed into cold, periglacial landscapes characterized by permafrost and tundra, while vast, dry grasslands (steppes) formed in more distant regions.5
* Feedback Loops: Changes in vegetation—such as the replacement of forests with tundra—altered the Earth's albedo and heat flux, reinforcing global cooling or warming trends.2