What causes ice ages?

Answer 1

This is very complicated (it involves lots of factors) but I will try and put it simply.

The most important factor is that for some considerable (geologic) time the composition of Earths atmosphere has been changing. The amount of CO2 in it has been decreasing. The CO2 has been gradually 'locked up' in limestone. As CO2 is a greenhouse gas, it presence in the air keeps the Earth warm. When there is too little of it in the air the Earth cools significantly and the planet becomes susceptible to other factors that affect it temperature.

The most important of these secondary factors is Earth's orbital cycles and its axial tilt. The Sun is the source of heat keeping the planet warm and as the Earth orbits the Sun, at various stages of the orbit the amount of the Sun's heat hitting the sea/land varies. (see related link below).

The next factor is the process by which heat is distributed round the world and the reflectivity of the Earth's surface. The equatorial areas are heated by the Sun most and the Poles least. This in turn heats the air and water near the equator and the ocean currents and Earth's weather system then carry hot air and water to the poles and cold air and water back. In the ocean these currents are vast and are called the ocean conveyor. Changes to these are involved in Ice ages.

Also the air currents bring precipitation to the poles as snow. Snow is white and reflects the Sun's energy back into space and this means as an Ice age starts and snow settles the planet cools fast. Conversely when snow melts the planet can warm very quickly.

OK the above are the factors and mechanisms involved in Earth's Ice age cycle. The key is that because of CO2 loss the average temperature of the planet has cooled enough to allow Ice ages to happen. The current configuration of the continents and the Earth's axial tilt means that the variations in Earth orbit round the Sun causes phases of warmer and cooler times and Earth's atmosphere and ocean in response to this amplify the heating/cooling effect resulting in an Ice Age cycle.

Cause of the Ice AgeThe cause of ice ages remains controversial for both the large-scale ice age periods and the smaller ebb and flow of glacial/interglacial periods within an ice age. The general consensus is that it is a combination of several important factors: atmospheric composition (the relative amounts of water vapor, carbon dioxide, methane, sulfur dioxide, and various other gases and particulates in the atmosphere), changes in the Earth's orbit around the Sun known as Milankovitch cycles (and possibly the Sun's orbit around the galaxy), the motion of tectonic plates resulting in changes in the relative location and amount of continental and oceanic crust on the Earth's surface, variations in solar output, the orbital dynamics of the Earth-Moon system, the impact of relatively large meteorites, and eruptions of supervolcanoes.
An Ice Age starts every 100,000 years! Scientist have proven this by they dig holes in snow in the Arctic and they can tell by the shape of the ice what the temperature was from up to 2 million years ago!

BTW this is from kailey a 10 year old!

Answer 2

Ice age is from when there is a dramatically drop of temperature for quite some time. It's when the Earth experiences such cold drops of climate.