0:00 The wind was howling like a hungry dog outside the tent, and the snow was piling up against the canvas, two feet deep in an hour.0:10 What an absolute glory of an evening for a venture!0:14 In our last expedition, we peered into the silent craters of the Moon to uncover how cosmic chaos shaped the skies, but tonight, pet, our compass points right back home.0:28 Pull your chair in closer to the fire, now.0:31 We're journeying twenty thousand years into the past, when the Earth itself decided to put on a coat of blue frost and never take it off.0:42 Back then, the great northern world didn't have green boreens or soft bogland.0:48 An immense sheet of ice, miles thick, marched down across whole continents.0:54 It swallowed rivers whole and locked up so much water that the very oceans dropped.1:01 You could have walked dry-shod across places where deep waves roll today.1:07 Now, imagine stepping out onto that endless white steppe.1:11 Your boots crunch against gravel and frosted grass.1:16 You look up, and the ground starts to shudder under your toes.1:21 Out of the blizzard looms a beast the size of a hay barn, draped in shaggy red hair that sweeps the snow.1:29 A woolly mammoth!1:30 Two great tusks curving outward like sickles, ten feet long, sweeping drifts aside just to find a mouthful of dry moss.1:40 And keeping pace in the shadows of the rocks?1:44 A saber-toothed cat, its amber eyes locked on the herd, armed with two curved daggers for teeth, built purely for ambush in the frozen scrub.1:55 Every single creature had a secret trick to survive the bite of the frost.2:01 Thick fat beneath the hide, double coats of woolly fur, and ears shrunk small so the cold couldn't steal their body heat.2:11 It wasn't a wasteland, you see.2:13 It was a thriving kingdom carved entirely out of frost!2:17 Whisht now...2:19 listen.2:19 How do we know any of this when not a single soul was there with a notebook?2:25 That's the finest mystery of the lot!2:28 Modern explorers don't just hike over the land; we drill right into its heart.2:34 High up in Greenland, scientists pull up ice cores, giant cylinders of ancient frost extracted from miles down.2:43 Trapped inside that frozen glass are tiny air bubbles.2:48 Literal pockets of ancient wind, sealed away like letters in a bottle!2:53 By testing that air, we can smell the exact atmosphere of the past and track the very winter the world began to warm.3:03 Then you have the bone detectives.3:05 A shovel hits something hard beneath the Siberian mud, and suddenly you aren't looking at rock.3:13 You're brushing clean a mammoth tooth, ridged like the tread of an enormous boot, or lifting the skull of an ancient cat from a bed of black tar.3:25 Every layer of earth is a page in the grandest expedition journal ever written.3:31 The great chill eventually broke, of course.3:35 The glaciers retreated, carving out our valleys and pouring back into the sea.3:41 The mammoths are gone, God rest them, leaving only their bones behind.3:47 But the adventure never ended.3:49 Whenever you hold a stone smoothed by a glacier, you're holding a ticket to that magnificent, thundering world of ice.3:58 Drink up your warm milk, now.4:01 The turf is burning down to grey ash, and your own warm bed is waiting.
