How many ice ages have there been?

Question

..and why do they happen

Answer 1

There are many different schools of thought on whether there have been many ice ages. One theory is that a mega ice age a bout a billion years ago covered the entire planet and its grip was only loosened by internal volcanic activity.

The intelligentia agree on one thing....there has been at least one, the most recent. The trouble with ice ages is that each one wipes away any evidence of a previous one.

The most recent "spate" of ice ages have been caused by the Isthmus of Panama closing and causing a redirection of ocean currents and moist air over the northern hemisphere. As the mosit air reached the cold latitudes, it turned to snow and..bingo.

Contrary to belief, ice ages aren't caused by bad winters, rather not so good summers. The summer temperatures aren't enough to melt winter ice casuing the ice to build up. Over a single lifetime, the climate can change dramatically.

Answer 2

There have been many ice ages in Earth's history. Here is a chart that shows average global temperatures over the last 2 billion years.http://www.scotese.com/climate.htm
During the Ice House periods the earth's climate could have been described as an ice age. There have been at least 4 major Ice House periods, but even within these there were cycles of colder and warmer climate. There is ample evidence to support these cycles of glaciation.


There are a number of factors that affect Earth's climate. The major factor that changes climate over time has been the pattern created by the variation in the Earth's orbit around the sun. The Earth changes in its distance from the sun and in its orientation to the sun as it orbits the sun. The three major variations are called eccentricity, obliquity, and precession.
They produce cycles in climate that are on 400,000 years, 100,000 years, 41,000 years, and 19-23,000 year frequencies. As the earth moves further away from the sun, ice ages are initiated and continue until the earth has moved back towards the sun. To see some diagrams of these orbital cycles of Earth check these websites:
http://www.uwsp.edu/geO/faculty/lemke/geol370/lecture_notes/16_causes_of_climatic_change.html
and
http://deschutes.gso.uri.edu/~rutherfo/milankovitch.html

Answer 3

You need your book for this. It depends on your definition of ice age. Was the "little" ice age of the middle ages, an Ice age. Can we really know how many ice ages there were 1 billion years ago?

Answer 4

There has been just one ice age
http://www.creationontheweb.com/content/view/3011/

Some scientists claim that there have been many ice ages, but there is no evidence for this - it is based on evolutionary thinking.

The key question is - what causes an ice age. You need warm seas and cold continents to create massive amounts of precipitation falling as snow. The slow and gradual evolutionary scenarios to explain the ice age do not work.

The global flood as described in the Bible does provide a simple mechanism for the ice age. The oceans would have been warm due to not subterranean water (the "fountains of the deep", and massive volcanic activity would have resulted in dust clouds reflecting back much heat from the sun.

Of course this explanation is discarded my some for religious (secular humanist/atheist) reasons.

Much info at the link above.