Ice ageFrom Wikipedia, the free encyclopediaJump to: navigation, searchFor other uses, see Ice age (disambiguation). This article or section is missing citations and/or footnotes. This article or section contains insufficiently sourced phrases. Using inline citations helps guard against copyright violations and factual inaccuracies. You may improve the article or discuss this issue on its talk page. Help on using footnotes is available. This article has been tagged since May 2007. Ice sheets expand during an ice age. This image is of the Antarctic ice sheet. Variations in temperature, CO2, and dust from the Vostok ice core over the last 400,000 yearsAn ice age is a period of long-term reduction in the temperature of Earth's climate, resulting in an expansion of the continental ice sheets, polar ice sheets and mountain glaciers ("glaciation"). Glaciologically, ice age is often used to mean a period of ice sheets in the northern and southern hemispheres; by this definition we are still in an ice age (because the Greenland and Antarctic ice sheets still exist). More colloquially, when speaking of the last few million years, ice age is used to refer to colder periods with extensive ice sheets over the North American and Eurasian continents: in this sense, the most recent ice age ended about 10,000 years ago. This article will use the term ice age in the former, glaciological, sense; and glacials for colder periods during ice ages and interglacials for the warmer periods.