Ice age

An ice age is a period of long-term 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. Within a long-term ice age, individual pulses of cold climate are termed "glacial periods" (or alternatively "glacials" or "glaciations" or colloquially as "ice age"), and intermittent warm periods are called "interglacials". Glaciologically, ice age implies the presence of extensive ice sheets in the northern and southern hemispheres. By this definition, we are in an interglacial period—the Holocene—of the ice age that began 2.6 million years ago at the start of the Pleistocene epoch, because the Greenland, Arctic, and Antarctic ice sheets still exist.

Origin of ice age theory

In 1742 Pierre Martel (1706–1767), an engineer and geographer living in Geneva, visited the valley of Chamonix in the Alps of Savoy. Two years later he published an account of his journey. 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. Later similar explanations were reported from other regions of the Alps. 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. An unknown woodcutter from Meiringen in the Bernese Oberland advocated a similar idea in a discussion with the Swiss-German geologist Jean de Charpentier (1786–1855) in 1834. Comparable explanations are also known from the Val de Ferret in the Valais and the Seeland in western Switzerland and in Goethe's scientific work. Such explanations could also be found in other parts of the world. When the Bavarian naturalist Ernst von Bibra (1806–1878) visited the Chilean Andes in 1849–1850, the natives attributed fossil moraines to the former action of glaciers.

Ice age (disambiguation)

An ice age is a geologic period of major glaciation.

Ice Age may also refer to:

Science

Music

Film

2012: Ice Age

2012: Ice Age is a 2011 disaster film produced by the independent film group The Asylum. It is the third and final film in The Asylum's 2012 trilogy, which are mockbusters of the Roland Emmerich film 2012.

Plot

Bill Hart and his son, Nelson drive his daughter Julia to the airport. Bill contacts Dr. Divya who informs Bill a team of scientists he works with has left Iceland. Divya is able to tell Bill an entire range of volcanoes has erupted and a 200-mile long ice shelf is breaking apart before he is killed by the volcanic eruptions. While Bill is distracted, Julia heads into the airport. At his office, Bill is advised to leave Maine and head to the West as soon as he can to avoid the destruction of the glacier. Bill and Nelson head to the Senator’s office and pick up his wife Teri. The glacier travels at high speeds, races towards the East Coast of North America, bringing heavy snow and giant hail. The Air Force attempts to break apart the glacier with aerial attacks, but fails.

Global cooling

Global cooling was a conjecture during the 1970s of imminent cooling of the Earth's surface and atmosphere culminating in a period of extensive glaciation. This hypothesis had little support in the scientific community, but gained temporary popular attention due to a combination of a slight downward trend of temperatures from the 1940s to the early 1970s and press reports that did not accurately reflect the full scope of the scientific climate literature, which showed a larger and faster-growing body of literature projecting future warming due to greenhouse gas emissions. The current scientific opinion on climate change is that the Earth has not durably cooled, but underwent global warming throughout the 20th century.

Introduction: general awareness and concern

In the 1970s, there was increasing awareness that estimates of global temperatures showed cooling since 1945, as well as the possibility of large scale warming due to emissions of greenhouse gases. Of those scientific papers considering climate trends over the 21st century, less than 10% inclined towards future cooling, while most papers predicted future warming. The general public had little awareness of carbon dioxide's effects on climate, but Science News in May 1959 forecast a 25% increase in atmospheric carbon dioxide in the 150 years from 1850 to 2000, with a consequent warming trend. The actual increase in this period was 29%. Paul R. Ehrlich mentioned climate change from greenhouse gases in 1968. By the time the idea of global cooling reached the public press in the mid-1970s temperatures had stopped falling, and there was concern in the climatological community about carbon dioxide's warming effects. In response to such reports, the World Meteorological Organization issued a warning in June 1976 that "a very significant warming of global climate" was probable.