At the start of the 20th century, Serbian mathematician and physicist Milutin Milanković decided to use math to determine how Earth’s ice ages had occurred.

First, he calculated how the amount of sun that Earth receives—its insolation—determines its temperature.

Then, he identified and explained Earth’s different climate zones based on their insolation.

Finally, he built a mathematical model to discover if Earth’s insolation is affected by three variations: a changing elliptical path around the Sun; a change in the tilt of Earth’s axis; and a wobble on that axis.

Though they cycle at vastly different time intervals, Milanković wondered if these variations could be shaping Earth’s long-term climate.

He worked the problem out with pen and paper while under house arrest during World War I, demonstrating how these cyclical variations interacted to reduce or amplify the effects of insolation, causing long cooler glacial and shorter warmer interglacial periods.

Milanković had calculated back 600,000 years, and his results lined up exactly with the geological record!

With this work, he founded the science of planetary climatology, modeling the climate of Earth and other planets over 100 years ago. His work is the basis of modern weather forecasting.

Human civilization developed in the most recent warm interglacial period of the last 10,000 years. But one day again, the ice man cometh!