Why Ice Ages Freeze Earth Every 100,000 Years

Every 100,000 years on our planet, an Ice Age occurs. During this time, temperatures plummet, leaving the world icy and cold. Now, scientists may have discovered why this is; they've learned exactly why our climate changes in such a drastic manner.

Ice ages and warm periods have alternated on our planet fairly regularly. What is most interesting, though, is the timing of these alternations. The ice ages, for example, occur once every 100,000 years. At that time, vast areas of North America, Europe and Asia are buried under thick ice sheets. When this ice recedes, it leaves behind glacial moraines, evidence of the past climate. While this evidence clearly shows that these events occur, though, they don't show scientists why.

That why the researchers used computer simulations in order to delve a bit deeper into the question of why ice ages occur. They combined ice-sheet simulation with an existing climate model. This allowed them to calculate the glaciation of the northern hemisphere for the last 400,000 years.

So what did they find? It turns out that the ice and warm periods interchange depending on the alternating influence of continental ice sheets and climate.

"If an entire continent is covered in a layer of ice that is 2,000 to 3,000 meters thick, the topography is completely different," said Heinz Blatter, one of the researchers, in a news release. "This and the different albedo of glacial ice compared to ice-free earth lead to considerable changes in the surface temperature and the air circulation in the atmosphere."

Feedback effects especially have great influence on this 100,000 year cycle. The general climate of the Earth greatly depends on the size of ice sheets. For example, in the case of smaller continental ice sheets that are still forming, periods with a warmer climate are less likely to melt this. This is a different story with a large ice sheet that stretches into lower geographic latitudes; a brief warm period is likely to melt it.

The cycle is also due to the Earth's orbit and its resulting insolation. Our planet's elliptical orbit around the sun changes in a cycle of around 100,000 years, which helps explain the regular cycle of ice ages.

The findings reveal a little bit more about how ice ages form and give way to warm periods. This could reveal what earth may be in store for in the future in addition to helping scientists learn more about our planet's past.

The findings are published in the journal Nature.