Uncover the lost world and giant beasts of frozen Earth

For most of Earth’s history, the planet has been free of ice, even at the poles. However, for the last 2.4 billion years, Earth has been cycling in and out of freezing ice ages. For millions of years at a time, temperat u res plum met and large areas of the g lobe become trapped under sheets of ice. These glacial periods start gradually. Snow falls during the w inter, and fails to melt in the su m mer, and over time, layer upon layer is built up. The white surface reflec ts sunlight back into space, and a c ycle of cooling begins.

Vast glaciers for m at the poles, creeping inwards towards the equator, and Earth’s water is locked away into slowly mov ing ice. As it creeps along, it carves great scars into the landscape beneath. When Earth’s water freezes, sea levels d rop, revealing land once h idden beneath the oceans. Winds and currents change direction, and even those places untouched by ice u ndergo significant climate change.

There have been at least five ice ages so far, the first of which transformed the entire planet into a giant snowball. However, within these periods of extreme chill, there have been occasional bursts of warmth. During each ice age, the Earth c ycles in and out of glaciation, freezing for tens of thousands of years, thawing temporarily, and then freezing again. As the glaciers warm, water floods back across the land, filling valleys and carving out new tracks in the landscape. Sea levels rise, and winds and currents shift. In fac t, we are in the middle of an ice age right now – but we are in a temporar y thaw that began around 11,000 years ago. These warm periods are known as ‘interglacials’ and we don’t know exactly how long they last for. Ice sheets still cover Antarctica and Greenland, trapping 75 per cent of Earth’s fresh water, and when these finally melt, it will mark the end of the current ice age. Until then, join us as we delve into the histor y of ice on Earth.