In 1815 the carpenter and chamois hunter Jean-Pierre Perraudin (1767–1858) explained erratic boulders in the Val de Bagnes in the Swiss canton of Valais as being due to glaciers previously extending further. Later similar explanations were reported from other regions of the Alps. He reported that the inhabitants of that valley attributed the dispersal of erratic boulders to the glaciers, saying that they had once extended much farther. Two years later he published an account of his journey. In 1742, Pierre Martel (1706–1767), an engineer and geographer living in Geneva, visited the valley of Chamonix in the Alps of Savoy. See also: History of climate change science The amount of anthropogenic greenhouse gases emitted into Earth's oceans and atmosphere is predicted to delay the next glacial period by between 100,000 and 500,000 years, which otherwise would begin in around 50,000 years. By this definition, Earth is in an interglacial period-the Holocene. In glaciology, ice age implies the presence of extensive ice sheets in the northern and southern hemispheres. Individual pulses of cold climate within an ice age are termed glacial periods (or, alternatively, glacials, glaciations, glacial stages, stadials, stades, or colloquially, ice ages), and intermittent warm periods within an ice age are called interglacials or interstadials. Earth is currently in the ice age called Quaternary glaciation. Earth's climate alternates between ice ages and greenhouse periods, during which there are no glaciers on the planet. For other uses, see Ice age (disambiguation).Īn artist's impression of ice age Earth at glacial maximum.Īn ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. For specific recent glacial periods often referred to as the "Ice Age", see Last Glacial Period, Pleistocene, and Quaternary glaciation. This article is about glacial periods in general.
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