Knowra Ice age Ice age A geological interval in which Earth has persistent ice sheets and glaciers, alternating with warmer intervals. The current ice age began about 2.6 million years ago and continues today.
Milankovitch cycles : Long-term variations in Earth's orbit and axial orientation that alter the distribution of incoming sunlight. They pace glacial and interglacial cycles by changing seasonal sunlight, especially at high northern latitudes.
Glacial period : A colder interval within an ice age when continental ice sheets expand. It is the icy phase that gives the broader interval its defining landscape.
Last Glacial Maximum : The point of maximum global ice extent during the last glacial period, about 26,000 to 19,000 years ago. It marks the most extensive recent configuration of ice sheets and low sea levels.
Eustatic sea level : The global average sea level, especially as altered by changes in the volume of ocean water. Water stored in continental ice lowers sea level during glacial periods and raises it during melting.
Albedo : The fraction of incoming radiation that a surface reflects rather than absorbs. Expanding bright ice reflects sunlight and reinforces cooling, while retreating ice weakens that feedback.
Interglacial : A relatively warm interval between glacial periods, when ice sheets retreat but do not disappear entirely. Interglacials interrupt glacial conditions without ending the larger ice age.
Younger Dryas : A sudden return to near-glacial conditions in the North Atlantic region about 12,900 to 11,700 years ago. This abrupt cold episode interrupted the warming that ended the last glacial period.
Glacial landform : A landscape feature created by the erosion, transport, or deposition of glacial ice. These landforms preserve the routes and former limits of advancing ice.
Greenhouse gas : An atmospheric gas that absorbs and emits infrared radiation, influencing Earth's surface temperature. Carbon dioxide and methane changes amplify temperature shifts across glacial cycles.
Ice sheet : A continental-scale mass of glacial ice covering more than 50,000 square kilometers. Ice sheets are the largest land-ice features that expand during glacial periods.
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