# Ice Ages **URL:** \ **Category:** Factual Questions\ **Created:** [May 30, 2009, 11:48pm UTC](https://boards.straightdope.com/t/ice-ages/498212 "2009-05-30T23:48:39Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![rawensley](https://avatars.discourse-cdn.com/v4/letter/r/f0a364/32.png) [@rawensley](https://boards.straightdope.com/u/rawensley)\ **Post date:** [May 30, 2009, 11:48pm UTC](https://boards.straightdope.com/t/ice-ages/498212/1 "2009-05-30T23:48:39Z")
How does an ice age form? replies please ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [May 31, 2009, 6:08am UTC](https://boards.straightdope.com/t/ice-ages/498212/2 "2009-05-31T06:08:41Z")
As I understand it, what happens is that for any of a number of reasons ( the Sun cooling off a bit, for example, or just random climate fluctuations going a bit farther than average ) the normal cooling down of winter passes a critical point. More ice and snow forms than usual, more plants die than usual; that means more sunlight is reflected and less carbon dioxide produced. That results in more cooling, which results in more ice and snow and more die offs, which produces yet more cooling, and so on. Eventually a new semi-stable climate is reached that lasts for thousands of years until something sets off a warming trend. And technically, we are in an ice age right now; we have ice at the poles. This is an interglacial, a period in an ice age when the ice sheets are mostly at the poles. ---
**Author:** ![janeslogin](https://avatars.discourse-cdn.com/v4/letter/j/df788c/32.png) [@janeslogin](https://boards.straightdope.com/u/janeslogin)\ **Post date:** [May 31, 2009, 3:34pm UTC](https://boards.straightdope.com/t/ice-ages/498212/3 "2009-05-31T15:34:43Z")
There are big academic books on this. The University of Alaska has a great collection. Fascinating stuff. Most variations in the textbooks are attributed to wobble in the rotation of the earth causing the sunlight to strike a more or less direct angles. ---
**Author:** ![Alka\_Seltzer](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alka\_Seltzer](https://boards.straightdope.com/u/Alka_Seltzer)\ **Post date:** [May 31, 2009, 4:10pm UTC](https://boards.straightdope.com/t/ice-ages/498212/4 "2009-05-31T16:10:15Z")
This article explains some of the factors that affect climate: [http://en.wikipedia.org/wiki/Milankovich\_cycles](http://en.wikipedia.org/wiki/Milankovich_cycles) Climate is imperfectly understood, as there are all kinds of positive and negative feedback mechanisms. Der Trihs mentioned advancing snowlines as an example of positive feedback, but things get more complicated when life is involved. ---
**Author:** ![janeslogin](https://avatars.discourse-cdn.com/v4/letter/j/df788c/32.png) [@janeslogin](https://boards.straightdope.com/u/janeslogin)\ **Post date:** [December 1, 2009, 11:16pm UTC](https://boards.straightdope.com/t/ice-ages/498212/5 "2009-12-01T23:16:24Z")
This is a test. Just testing what happens if one puts a reply on an old thread. OK. It moves the thread to the top again. My curiosity has been satiated, this time. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [December 1, 2009, 11:45pm UTC](https://boards.straightdope.com/t/ice-ages/498212/6 "2009-12-01T23:45:13Z")
Watch and see what else happens… ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [December 1, 2009, 11:47pm UTC](https://boards.straightdope.com/t/ice-ages/498212/7 "2009-12-01T23:47:35Z")
Zombie. Nothing new added. Closed.