What is an Ice Age? (with photos)

Neanderthals evolved to survive in the harsh climate of Ice Age Europe.

An Ice Age is a period of time, typically about 30 million but occasionally as long as 300 million years, during which ice sheets cover at least the polar areas of the Earth. Individual Ice Ages have sub-Ice Ages, called glacial (when cold) or interglacial (when warmer) that operate in cycles of 40,000 and 100,000 years. When the term “Ice Age” is used colloquially, it usually refers to these shorter glaciers, periods when the polar ice caps extend significantly beyond the poles and into the heart of continents such as North America and Eurasia. In this sense, “the last Ice Age” refers to what is formally termed “the last glacial period”, which began around 70,000 BP and ended between 15,000 and 10,000 BP. This is the Ice Age experienced by primitive man.

During the most recent ice age, Alaska was connected to Russia by the Bering Land Bridge.

Scientists cannot say exactly what causes the Ice Age, although there are a number of implied variables at play. These include atmospheric composition (greenhouse gases), small changes in the Earth’s orbit known as Milankovitch cycles, the Earth’s albedo (reflectivity), changes in the location and amount of crust at different points on the Earth’s surface, variations in production solar, large meteor impact, the release of methane clathrates and supervolcanism. Short-term cycles (40,000 / 100,000 years) are known to be caused by variations in Earth’s orbit.

The ice covering Greenland indicates that the world is in the midst of an Ice Age that began 40 million years ago.

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As there is ice covering Antarctica and Greenland, we are in the midst of an Ice Age, which began 40 million years ago. Ice ages are very unusual circumstances for Earth; with the exception of six Ice Ages, the Earth’s poles were virtually ice-free. Tree fossils have been found in lands that were only a few hundred kilometers from the poles at the time they lived. Ice ages are as rare as mass extinctions, occurring once every 100 million years or so.

The typical average global temperature when the Earth is not in an Ice Age is around 22 °C (71.6 °F). During the Ice Age, it drops by about 10 °C to an average of 12 °C (53.6 °F). At the poles, the temperature is well below freezing practically all the time.

During the Ice Age, large amounts of water become trapped in ice sheets, lowering the global sea level. During the most recent Ice Age, global sea level was about 30 meters lower than it is now, opening up large sections of land such as the North Sea and connecting Papua New Guinea to Southeast Asia and from Russia to Alaska via Bering Land bridge. Because of the Ice Age, our ancestors were able to cross into the Americas. It would be over 10,000 years before humans who traveled to the Americas were reunited with their distant cousins ​​in Europe, Asia and Africa.

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