The earliest known major ice age, which gripped the young Earth almost two billion years ago.
One of the most extreme ice ages ever, in which the entire planet may have been covered with ice from pole to equator.
An ice age during the Ordovician and Silurian that coincided with one of the largest mass extinctions in Earth's history.
A prolonged ice age during the Carboniferous and Permian that drastically changed the appearance of the supercontinent Gondwana.
The beginning of the earth's current long-term cooling, with the first permanent ice sheet on Antarctica.
The start of the series of ice ages and interglacials that have alternately affected the northern hemisphere to this day.
The coldest point of the last ice age, when enormous ice sheets covered North America and Northern Europe and sea levels were metres lower.
The rapid warming that melted the ice sheets and ushered in the current, relatively stable climatic era.
The current era, in which human emissions of greenhouse gases threaten to disrupt the natural rhythm of ice ages and interglacial periods.
A speculative look at a distant future in which the earth, after centuries of human-induced warming, may nonetheless enter a new ice age.
Mammoths, woolly rhinoceroses and cave lions populated the cold steppes of Eurasia, while Homo sapiens had spread across virtually the entire globe and reached North America via the then-dry Bering land bridge. Neanderthals had by then gone extinct. Large parts of what is now the Netherlands, Germany and Scandinavia lay under kilometres-thick ice or consisted of bare tundra marked by permafrost.