Glaciers advance and retreat

Artwork depicting a herd of mammoths

About 2.6 million years ago at the start of Pleistocene epoch, large ice sheets up to several kilometres thick began to appear in the northern hemisphere. These ice sheets would advance during cooler glacial periods and retreat during warmer interglacials.

We are living during an interglacial period called the Holocene that started about 11,500 years ago.

Ice ages are powerful evidence of the natural climate change that has occurred on the Earth in the geological past. In the 21st century the effect that humans are having on this natural cycle is an area of active scientific investigation.

Image: Artist's impression of a herd of woolly mammoths, creatures that lived during the last glacial period and went extinct about 10,000 years ago (credit: Christian Darkin/SPL)

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Glaciers advance and retreat

The Quaternary glaciation, also known as the Pleistocene glaciation or the current ice age, is a series of glacial events separated by interglacial events during the Quaternary period from 2.58 Ma (million years ago) to present. During this period, ice sheets expanded, notably from out of Antarctica and Greenland, and fluctuating ice sheets occurred elsewhere (for example, the Laurentide ice sheet). The major effects of the ice age are erosion and deposition of material over large parts of the continents, modification of river systems, creation of millions of lakes, changes in sea level, development of pluvial lakes far from the ice margins, isostatic adjustment of the crust, and abnormal winds. It affected oceans, flooding, and biological communities. The ice sheets themselves, by raising the albedo, affect a major feedback on climate cooling.

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