Ice Ages

The weather changes all the time. It can change in a matter of minutes. Climate changes more slowly. But even small changes can make a big difference for Earth and its living things. 

Over the Earth's past, the climate has changed. There have been ice ages, which are periods when temperatures are cooler than normal. This causes glaciers to spread to lower latitudes. There have also been interglacials, periods where temperatures are warmer. 

The last major ice age took place in the Pleistocene, which occurred from about 2 million years ago to approximately 10,000 years ago.  During the Pleistocene, Earth's temperature was about 5ºC (9ºF) cooler than today. Glaciers covered much of North America.

Pleistocene glaciers covered a large area of North America. Image courtesy of CK-12. 

The decrease in temperature led to greater amounts of precipitation falling as snow, which caused glaciers to become more widespread. This, in turn, led to drops in sea level. This exposed the shallow continental shelves, including the shelf that connects Asia with Alaska. This is believed to be the route by which Pleistocene hunters crossed into North America. It also caused many organisms to adapt to cooler temperatures. 

Source: Climate Change. Retrieved from http://www.ck12.org/section/Climate-Change-%253A%253Aof%253A%253A-MS-Climate/ on August 27, 2013. 

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Last modified: Monday, 12 February 2018, 11:35 AM