"This is our planet, the Earth." "It's unique in the solar system, perhaps even in the universe." "My name is Iain Stewart and I want to show you how our planet works." "I am exploring ice." "Ice may be nothing more than frozen water but it holds extraordinary power." "Since human beings have been on the planet, nothing has done more than ice to shape our world." "It has carved the landscape, unleashed terrible catastrophes and ice has helped drive the climate of the whole planet." "It's even changed the course of human evolution, yet it may also threaten our future." "Only now are we beginning to understand the power of this remarkable substance." "Welcome to the world of ice." "The Alps." "One of the world's great mountain ranges." "Its peaks reach almost three miles into the sky." "It's a vertical landscape of snow and ice where even waterfalls can freeze." "If you want to understand the power of ice to transform our world, this is a great place to begin." "This is amazing stuff, you know, because... (GRUNTING) ...it's so solid and it can hold my weight." "It really is surprising how solid ice is, or I hope it is." "I find it astonishing that hundreds of tons of cascading water can be stopped dead in its tracks." "But this frozen waterfall is nothing compared to the ice that's all around me in the form of glaciers." "I'm climbing right next to one of the largest in France, the Argentiere." "Glaciers are ice at its most powerful." "They're nature's bulldozers, capable of completely reshaping the landscape." "Thing is, that giant icicle I've just climbed up is made of frozen water, it formed this year, whereas that glacial ice up there, formed over thousands of years in a completely different way." "Glaciers are not formed from frozen water." "They are made from snow." "Every snowflake is formed from dozens of delicate ice crystals." "No one has ever found two that are the same." "Individual snowflakes may be fragile but put enough together and they create one of the most awe-inspiring sights in nature." "Every year around a million avalanches thunder down the Earth's mountains." "But however devastating avalanches may appear to us, when it comes to reshaping the Earth, they barely even scratch the surface." "When snow turns into ice, it becomes so powerful it can change our world." "On this ice cliff you can actually see the transformation of snow into ice as it happens." "Each year's snowfall creates distinct layers many feet deep." "Now, above me is the fresh snow from this winter, and down here, this brown line is the melt from the summer before." "So as you go down through these layers, the snow gets older and older." "It's kind of like the rings of a tree with each layer being a new layer of snowfall, and it's the weight of all those snowfalls building up that starts to compress the individual snowflakes together." "The further down the layers you go, the harder the snow becomes until you reach here." "This is a really distinctive set of snow." "It's called neve and it formed several years ago." "It's really hard, I mean, I have to dig at it with my ice axe." "It's amazing stuff." "It's kind of like a bubbly fiberglass." "It's beautiful." "The more the snow is compressed, the more air is forced out of it." "Removing air is what turns fluffy snow into rock hard ice." "This is it." "I've come down about 20 meters to the base of the cliff and this is pure glacial ice." "All those snowflake crystals in there have been squeezed down and it gives this weird texture." "I mean, it's just frozen water but it's like solid rock." "Look at that." "And it's got this glassy feel to it." "It's almost transparent." "When enough ice forms, it slowly starts to slide downhill and becomes a glacier." "And over the last couple million years, it's ice that has been a dominant force shaping our world, even changing the climate." "Recorded from deep within the ice, these are the sounds of a glacier groaning and creaking as it slides down the mountain." "(RUMBLING)" "(CREAKING)" "They may move too slowly for the human eye to appreciate, but as a speeded-up film of the Argentiere glacier shows, ice is very much on the move." "Instruments underneath the Argentiere reveal that it's traveling at about a foot and a half a day." "Here in Europe, ice is confined to high mountain ranges." "But in the polar regions, it's cold enough for ice to cover vast areas of land." "In Antarctica, a single ice sheet buries a continent bigger than the United States." "The ice sheet can reach a staggering two and a half miles thick so only the peaks of high mountains, called nunataks, can poke through." "This is a world where ice doesn't so much carve out a landscape, it is the landscape." "This ice world is so huge that some of its greatest wonders can only be seen from space." "These are mega dunes of ice, carved by centuries of relentless winds." "Each dune is three miles from the next." "Together they cover an area about the size of California." "The polar ice even creates its own climate." "The air is so cold that it holds almost no moisture so Antarctica is the driest continent on Earth." "But beneath the ice is another even more magical world, one that's been lost for more than 1 0 million years." "This satellite image reveals a huge area of flat ice, flat because it's floating on top of an enormous lake." "It's called Lake Vostok." "It lies beneath nearly two miles of ice." "The lake has been isolated from the rest of the planet for millions of years." "It may even be home to forms of life we've never seen." "And thanks to radar now, for the first time, it's possible to see the complete landscape that lies buried beneath Antarctica's ice." "It's a strange and unfamiliar world of islands and mountains that's never been seen by humans." "We may take it for granted that snow and ice are very much part of our world and that glaciers and ice sheets seem to be a permanent feature of the landscape but, in fact, nothing could be further from the truth." "As far as Earth is concerned, ice is pretty unusual." "For most of our planet's long history, about 90% of it, there's been virtually no ice at all." "Even the dinosaurs that hung around for 200 million years never saw anything like this." "Our current era is actually an unusual time in Earth's history." "It's called an ice age, an era when ice sheets covered large areas of the planet." "It began around three million years ago." "when the continents of North and South America collided." "The result, a warm ocean current that flowed around the equator was cut off" "so now the warm water traveled north." "Today we know this current as the Gulf Stream." "Strange as it may appear it seems this warm current is what tipped the planet into an ice age." "Its warm waters brought more moisture to the cold northern regions of the planet, so more snow fell, and ice began to build up." "Slowly the Northern Hemisphere iced over triggering a global cooling." "In the last million years, the ice has advanced and retreated 1 0 times in a cycle, aided by small changes in the Earth's orbit." "Although a few million years is just the blink of an eye in the planet's life, this recent ice age has had an extraordinary influence on our world, and on us." "It changed the climate across the planet." "In doing so, it helped drive human evolution." "Most obviously, it physically carved much of the world we know today." "Yosemite National Park in California shows just how powerful ice is at shaping the landscape on a gigantic scale." "Rising up from the valley floor is an icon of nature." "And a climber's Mecca, El Capitan." "For Leo Holding, an extreme climber nothing quite matches this." "And it's the ice that has made El Cap into perhaps the greatest challenge in rock climbing." "HOLDING:" "We call El Cap the Big Daddy." "This is 1,000 meters high and it's damn near vertical the whole way." "Your initial reaction is terror." "The scale of it is really intimidating, even to extremely experienced climbers." "There's basically no easy way up it." "It's the hardest cliff to climb in the world." "The rock face is almost vertical." "The ice took a mountain of granite and over tens of thousands of years, sliced one side of it away, which is why this cliff is so steep." "I've been climbing for the last few hundred feet." "Crack's about to run out." "When the cracks run out, you get into these blank faces that are almost impossible to climb." "In fact, you can see it's so smooth, the rock, you hold on to virtually nothing." "STEWART:" "The glacier moved across the granite, grinding it with a force of hundreds of pounds on every square inch." "It buffed the rock to a high polish." "(GRUNTING)" "Whoa !" "I' m slipping, I' m slipping." "I' m right at the limit of friction." "(GASPING)" "Oh, it's just so smooth and slippery." "You have to keep your weight close into the wall." "(THUNDER RUMBLING)" "STEWART:" "Bad weather is closing in." "Even a little rain on such smooth rock is potentially lethal." "It's getting really wet and this glassy rock is just turning into an ice rink." "In fact, I might fall off here." "Oh, my God !" "There's quite a good chance I' m going to fall off." "STEW ART:" "It would be reckless to continue climbing." "Oh !" "Leo must find one of the few refuges El Cap has to offer." "Even when it's raining, it's just such an awesome sensation to be up here." "Okay, Dave, I' m safe." "Brilliant, what an awesome climb." "Magical place." "It's like Mother Nature created this place for rock climbers." "Some climbers prepare to spend the night on El Capitan, hoping to climb the next day." "It's easy to imagine that the ice age shaped only remote mountain ranges but it also left a legacy that has affected millions of people." "Take, for example, Manhattan." "When you look at it from a distance, it's actually got a very distinctive profile." "There are two clusters of skyscrapers with much lower buildings in the middle." "This is a direct result of the ice age." "Twenty thousand years ago, this part of America was at the edge of a vast ice sheet." "It covered much of the Northern Hemisphere." "In some places, the ice would have towered over any modern skyscraper." "When it retreated, just as in Yosemite, the ice left behind these boulders and rock smoothed and polished by ice." "The ice exposed a hard bedrock called schist, solid enough for sinking deep foundations" "to support tall buildings." "Without this bedrock, New York could not have been built so high." "The one part of the skyline that dips is the one place where the ice sheet deposited loose sand and gravel," "no good for building towering skyscrapers." "Ice has bulldozed and carved the world we know on a colossal scale." "But what is it that gives something as brittle as ice supremacy over the hardest and most resilient rocks to be found on the planet?" "To find out, you need to see inside a glacier." "The Svartisen Glacier in Norway is one of the few places on Earth where ice can really be seen in action." "It's thanks to this glacier that scientists are starting to understand the secrets of ice's great power." "Deep beneath the glacier in a chamber at the end, scientists come face to face with ice." "Then it's two days of of hard work using hot water to melt a cave big enough to get inside the glacier and see it in all its glory." "Here's the ice tunnel." "Watch your head !" "Miriam Jackson's a glaciologist." "She spends up to three weeks at a time down here." "Look at that!" "STEWART:" "It's beautiful!" "It's amazing, isn't it?" "It's absolutely beautiful." "This is like a piece of art." "It is, isn't it?" "Wow!" "You've got to remember there's 200 meters of ice over us now." "200 meters?" "JACKSON :" "Yes, we' re at the bottom of the glacier and the ice is over us." "It's also closing in on us." "As we speak, it's contracting in?" "Yeah." "We couldn't stand here for 48 hours, the ice would close in on us." "We' d be stuck fossilized in the ice, like a big ice cube." "It's down here, right at the very bottom of the glacier that you can see how it carves out great landscapes and can slice through solid rock." "It's not the ice itself that does all the damage." "It's the debris that it picks up along the way that makes glaciers act like giant sandpaper." "In effect, the ice uses the rock against itself." "But the ice cave has another surprise." "Have you seen this?" "It's an air bubble, is it?" "It's not an air bubble, this is water here." "Oh, look at that!" "So, we opened this up when we were melting, but before then, it was totally enclosed in the ice." "These water pockets apparently make the ice less brittle, so it can bend around obstacles in the landscape." "A glacier is not the solid mass that it first appears." "Seeing it from the inside has given me a completely different perspective." "It seems almost alive." "As if to prove the point, the ice invades the space we've left behind." "In just three days, our magical ice cave disappears." "From space you can really see how fluid ice is." "On the west coast of Greenland, glaciers flow around the contours of a landscape hidden beneath the ice." "A false color image reveals the blue ice of the Malaspina Glacier in Alaska." "It flows through a gap in the mountains and spreads out like syrup for more than 30 miles." "This is part of the Lambert Glacier in Antarctica." "It's one of the longest glaciers on Earth." "You can follow its flow lines as it bends and twists on its slow-motion descent." "Ice is soft and bendy, yet it's also powerful enough to destroy almost everything in its path." "But while glaciers usually take tens of thousands of years to sculpt the landscape, occasionally, they can trigger a devastating change that happens in just a few hours." "You can see the aftermath of one such event in the northwest corner of the United States." "It's a land of gorges, canyons and barren rock covering thousands of square miles." "It's known as the Scablands." "Vic Baker is a geologist who has spent 40 years trying to discover exactly what took place here." "The landscape creates this impression of something fantastic that happened, and as you drive through it, you can have a sense that you' re following the path of that great catastrophe." "Around 1 6,000 years ago, a giant lake formed, Lake Missoula, that was held back by nothing more than a wall of ice, a part of what's known as the Cordilleran ice sheet." "Behind me would be the ice dam that was holding in glacial Lake Missoula, and it was holding back a phenomenal amount of water." "STEW ART:" "As the huge mass of water built up behind the dam year after year the dam began to weaken." "Until the ice gave way in a catastrophic failure." "A mass of water larger than lakes Eerie and Ontario combined." "The force of water rushing forward was like releasing a bomb." "It generated a shockwave of air." "First thing, you' d see dust and wind, and you' d feel rumbling." "STEWART:" "An enormous flood quickly followed." "Lake Missoula's water had begun a fast and furious journey across the American continent." "BAKER:" "It would be moving very fast." "We' re driving at just about the same speed as the water." "STEWART:" "It would have torn through the landscape with the energy equivalent of 60 Amazon Rivers." "It would have ripped up everything in its path." "You can imagine water a hundred meters above your head, all dark, filled with sediment and all kinds of debris, large rocks, trees, woolly mammoths, anything." "I think it would be absolutely terrifying." "STEW ART:" "The water cut into the land up to 650 feet deep, excavating billions of tons of solid rock." "It would probably be described as a kind of giant monster." "STEW ART:" "In just days, it smashed a path from source to ocean, for hundreds of miles," "leaving behind a colossal canyon." "And when the flood reached the sea, it sent sediment shooting out vast distances across the ocean floor." "The ice age flood had left behind extraordinary scars on the landscape." "This was once a waterfall several times the width of Niagara." "These are giant ripples formed by the turbulent flood water." "And huge potholes were created by whirlpools that drilled straight down into the rock." "The flood was so vast, it's difficult to imagine a catastrophe on this scale occurring today." "But we now know that as the ice advanced and retreated during the ice age, there were lots of floods on this scale in many parts of the world." "Since humans evolved, it's ice, through glaciers, ice sheets and floods, that has been the dominant force shaping our planet." "But the greatest influence of ice relies on far more than brute force." "That's because ice has some unusual properties that have a profound effect on the Earth's climate." "I am on the west coast of Greenland in what's known as Iceberg Alley." "This is the biggest iceberg factory in the world." "I've never been up this close to icebergs before." "I know they' re chunks of glacier that fall off the front of the ice sheet and they float here, but when you get this close, they' re like majestic beautiful ships flowing silently by." "This is known as an iceberg nursery." "Most substances are denser when solid than when liquid which means they sink." "Ice is an exception." "Because it expands when it freezes, it becomes less dense and so it floats." "It's also dazzlingly bright, which makes it highly reflective, and this combination has a dramatic effect on the Earth's climate." "These two qualities, floating and reflecting, make ice uniquely powerful on Earth." "Ice turns these polar regions into two giant reflectors, and they don't just reflect light but heat." "Land and sea are dark so they absorb the Sun's warmth, but ice reflects it straight back out to space." "It's called the albedo effect." "Filmed for a year from a satellite above the North Pole, you can see how the Arctic sea ice grows and shrinks with the seasons." "This changes the amount of energy absorbed by the Earth, and this in turn can influence the climate right across the planet." "So the amount of ice cover can have a dramatic effect on climate worldwide, one that may even have affected the path of human evolution." "Fossils found all over Africa show how in the last three million years there appear to have been two great evolutionary leaps forward." "The first was the appearance of an ape man with a larger brain." "Then later came the evolution ofHomo erectus, who was the first to make sophisticated stone tools." "But what caused these rapid changes has always been a bit of a mystery." "It now seems that they tie in with the two greatest advances of the ice sheets." "Each time the ice advanced, more of the Sun's energy was reflected from the planet." "This contributed to more extreme climatic conditions around the world." "In East Africa, home to our ancestors, the climate became unstable and unpredictable." "In this fast-changing world, those who adapted best thrived." "Both big brains and new weapons gave our ancestors an edge." "Eventually, out of the climatic turmoil modern humans began to emerge." "If it wasn't for the recent ice age helping to drive climate change in East Africa, we might not be here at all." "So what does the future hold for the planet's ice, now that the Earth's climate is warming?" "A good place to find out is Greenland." "Greenland is an island covered by the second largest ice sheet on the planet." "On the west coast is the massive Jakobshavn Glacier." "It's become the front line in scientists` attempts to understand what's happening to the world's ice today." "Until as recently as 1997, the glacier was relatively stable." "But since then, it's changed dramatically." "In the last five years, it's retreated over six miles." "It might seem strange, but the reason the glacier's retreated so much is because it's started flowing faster." "The Jakobshavn Glacier is now moving at over 130 feet a day, the fastest in the world." "The faster it flows, the thinner it becomes." "This weakens the ice, causing it to break up." "The result, the fjord is jam-packed with ice that has broken off the front of the glacier and is drifting off to sea." "Filmed over three months, it's possible to see just how much of Jakobshavn`s ice is floating away." "These are worrying signs and they're completely changing our understanding of Greenland's ice." "And it's not only the Jakobshavn Glacier there are other big glaciers along this coast that are also speeding up." "This could lead to the eventual disappearance of all of Greenland's ice, 1 0% of the world's total." "If that were to happen, it could raise sea levels by at least 20 feet, which would flood many of the most highly populated regions of the world." "Florida would be one of the worst places to suffer." "The northern coast of Europe would be barely recognizable." "Much of London would disappear." "So, not surprisingly, scientists are eager to find out what's happening to Greenland's ice as global temperatures continue to rise." "KONRAD STEFFEN :" "Well, the landscape is very special, as you can see, and on top of it, it never gets dark." "STEWART:" "Yeah, the Sun, it's fantastic." "I've joined up with Konnie Steffen." "We're on a part of the ice sheet that's connected to the Jakobshavn Glacier." "Konnie`s trying to understand what's causing the ice to speed up and break off into the sea, and whether it's related to climate change." "The ice moved fast, at first by 10%, then by 2002, 30-40% and it produced more water, like this river." "And this water is probably the explanation why the ice here starts to move faster." "STEW ART:" "Each summer as a result of rising temperatures, more and more melt water is forming lakes and rivers on the surface of the ice." "And this is where all the water flows, into deep shafts called moulins." "No one knows for sure where the water ends up when it disappears into the moulins, but Konnie believes it flows straight to the base of the glacier." "If he's right, this could explain why the glacier is moving so fast." "So far no one has been able to prove if the melt water actually does reach the bedrock and lubricate the ice sheet," "or if it simply flows through the ice, never reaching the bottom at all." "Now Konnie and his team hope to solve this mystery." "They're using a camera built by NASA designed to withstand extreme temperatures." "It could finally answer the question of whether the increased amount of water is actually speeding up the flow of ice." "If it is, then he will have made a direct connection between climate change and the disappearing glacier." "This is the first time it's gone down a natural moulin?" "This is the first, and maybe the last." "STEWART:" "They've got nearly 1,300 feet of cable, which Konnie believes is long enough to lower the camera all the way to the bedrock." "Sixty meters." "This is amazing." "Seventy meters." "Seventy meters." "Finally, nearly 330 feet down, we've reached melt water." "Now it's a lot, yeah." "It's a good sign that the camera's on the right track." "But if this water does reach the very bottom of the ice, there's still a long way to go." "I think it's stuck." "I think it's stuck." "The camera seems to have reached a bend in the moulin and it's not moving." "It's hit a ledge." "STEFFEN :" "We have to pull it back." "It could be just a kink in the moulin or it could be the water never reaches the bedrock." "For the moment, it will have to remain a mystery." "Konnie and his team will have to redesign the camera and return next summer." "But wherever this water ends up, it's clear that more surface ice is melting." "Scientists have mapped the area of the Greenland ice sheet that experiences surface melting in summer." "As recently as the 1 990s, it was a relatively small area around the edges of the ice sheet." "But by 2005, the melt Zone had massively expanded." "This would be bad enough on its own but if the melt water is also causing the glaciers to accelerate into the sea, it could have very serious consequences." "There seems to be no doubt that Greenland's ice is moving and changing faster than we ever conceived of even five years ago." "What's more, because this process continues every summer, the whole ice cap loses elevation, which means it'll be sitting in warmer temperatures and that, of course, means more melting, more of these moulins and so an even faster demise." "And it isn't only Greenland's ice that's under threat." "Around the world, it's the same story." "This is the Columbia Glacier in Alaska." "Like Jakobshavn, this is a fast moving glacier that ends up in the sea." "It's about a mile and a half wide and about half a mile thick." "But just 20 years ago, it was nearly twice as thick." "The line around the valley shows where the ice used to reach." "It's like a high tide mark." "This change has had a devastating effect." "Where the glacier meets the ocean, the result is clear." "Chunks of ice are falling into the sea 30 times faster than before." "As the ice gets thinner the process accelerates." "Since 1980, the Columbia has retreated over nine miles." "In fact, in the past 50 years, glaciers have been shrinking all over the world." "The floating ice shelves that surround Antarctica are also disintegrating." "This one collapsed in just five weeks, destroying an area of ice in excess of 1,100 square miles." "There is now no doubt that the world's ice is in retreat." "It's melting at a phenomenal rate, and it's likely to accelerate over the next few years." "It's still not possible to say for certain how much ice on the planet will vanish, or how fast." "For the planet, being without ice will be nothing unusual" "But for humans, the loss of ice will transform the appearance of the planet." "It will be the most visible change on the Earth since the dawn of civilization."