Editing Ice age (section)

===Position of the continents===
The geological record appears to show that ice ages start when the continents are in [[Continental drift|positions]] which block or reduce the flow of warm water from the equator to the poles and thus allow ice sheets to form. The ice sheets increase Earth's [[albedo|reflectivity]] and thus reduce the absorption of solar radiation. With less radiation absorbed the atmosphere cools; the cooling allows the ice sheets to grow, which further increases reflectivity in a [[positive feedback]] loop. The ice age continues until the reduction in weathering causes an increase in the [[greenhouse effect]].

There are three main contributors from the layout of the continents that obstruct the movement of warm water to the poles:<ref>Lee Hannah, ''Climate Change Biology'', 2nd ed. (Amsterdam: Academic Press, 2014), 23–28. {{ISBN|012799923X}}</ref>

* A continent sits on top of a pole, as [[Antarctica]] does today.
* A polar sea is almost land-locked, as the Arctic Ocean is today.
* A supercontinent covers most of the equator, as [[Rodinia]] did during the [[Cryogenian]] period.

Since today's Earth has a continent over the South Pole and an almost land-locked ocean over the North Pole, geologists believe that Earth will continue to experience glacial periods in the geologically near future.

Some scientists believe that the [[Himalayas]] are a major factor in the current ice age, because these mountains have increased Earth's total rainfall and therefore the rate at which carbon dioxide is washed out of the atmosphere, decreasing the greenhouse effect.<ref name="Raymo 649–653"/> The Himalayas' formation started about 70 million years ago when the [[Indo-Australian Plate]] collided with the [[Eurasian Plate]], and the Himalayas are still rising by about 5&nbsp;mm per year because the Indo-Australian plate is still moving at 67&nbsp;mm/year. The history of the Himalayas broadly fits the long-term decrease in Earth's average temperature since the [[Eocene|mid-Eocene]], 40 million years ago.