Glacial period
A span of geological time when continental ice sheets expand and global temperatures fall. Glacial periods are colder phases within longer ice ages.
Milankovitch cycles: Long-term variations in Earth's orbit and axial orientation that alter the distribution of incoming sunlight. Changes in seasonal sunlight can initiate or pace ice-sheet expansion.
Last Glacial Period: The most recent glacial period, lasting from about 115,000 to 11,700 years ago. It is the latest well-studied example of continental ice expansion.
Glaciation: The growth and movement of glaciers or ice sheets, and the geological processes they cause. Glaciation describes the ice expansion that characterizes a glacial period.
Glacial landform: A geological feature formed by the erosion or deposition of glacial ice. Landforms preserve the footprints of past ice-sheet movement.
Ice-albedo feedback: A climate feedback in which expanding ice reflects more sunlight, promoting further cooling and ice growth. This amplifying loop helps small cooling shifts produce extensive glaciation.
Last Glacial Maximum: The interval when global ice sheets reached their greatest extent during the Last Glacial Period, around 26,000 to 19,000 years ago. Its peak ice extent offers a snapshot of a mature glacial climate.
Interglacial: A relatively warm interval between glacial periods within an ice age. Interglacials are the warmer phases that interrupt repeated glacial periods.
Sea-level change: A rise or fall in the height of the sea relative to the land or a fixed reference. Water stored in expanding ice sheets lowered global sea level.
Carbon dioxide in Earth's atmosphere: The atmospheric concentration of carbon dioxide, a greenhouse gas that influences Earth's climate. Its decline during glacial cycles strengthens cooling, while rising levels help end glaciations.
Pleistocene: The geological epoch from about 2.58 million to 11,700 years ago, marked by repeated glacial cycles. Most familiar glacial periods of the recent geological past occurred within this epoch.