"Of all the planets in our universe, there is only one we know can support life." "just the right distance from its sun with a perfect climate." "It's been called the lucky planet." "About five billion years ago, a huge asteroid crashed into Earth tilting it at an angle of exactly 23 and a half degrees to the sun." "This cataclysmic accident turned out to be nothing short of a miracle." "Without that crucial tilt, everything would have been different." "For it created the seasons, the extremes of climate, hot and cold, and landscapes of spectacular beauty." "The perfect conditions for life on Earth." "All life on Earth is built on chance and powered by the sun." "But the delicate balances of our world are faltering, as the planet struggles to support our growing demands." "This is the time to take stock of what we have and what we stand to lose." "We follow a year on Earth, joining our fellow creatures as they battle to raise their young in a world that is rapidly changing." "January, the high Arctic, and there has been no sun for over a month." "At this time of year, it's permanent night." "Male polar bears are on winter patrol, but there is little to eat." "Every living thing is just waiting." "February, and the sun makes its first appearance over the horizon." "This female bear has been underground in her den the whole winter." "She toboggans down the slope." "Perhaps it's just to clean her fur, but it looks like sheer joy." "She hasn't been alone down there." "Her cubs were born underground." "They're two months old, but this is the very first time they've seen the light of day." "They're drawn to their mother's calls, but these slopes are not the easiest place to take your first steps." "The cubs haven't been fed this morning." "The mother has delayed their first meal on this special day." "Hunger will draw them to her." "It's the beginning of their training." "Milk is the only food the cubs have known since they were born deaf and blind beneath the snow." "The mother hasn't eaten for five months, and has lost half her body weight." "She's giving the last of her reserves to her cubs." "She can't leave yet in search of food." "She's trapped on these slopes until the cubs find their feet." "It's a trial female bears have always endured." "Every year at this time, female bears need food desperately." "They know they must get down to their hunting grounds on the ice." "What they can't know, is there's a problem waiting for them there." "A new problem." "our planet is warming and the sea ice is melting earlier every year." "This is the only place the bears can hunt for seals." "If they don't make it there before the ice breaks up, their families will starve." "So far this year, the ice holds firm, firm enough to support the male polar bear, the father of the cubs, as he searches for his prey." "He won't help the female." "Instinct makes him fend for himself alone." "Ten days later, and the starving mother is trying to lead her young down to the sea ice." "They've found their feet now, but they still don't share her sense of urgency." "At last, everyone seems ready for the journey, but it may already be too late." "A few miles from the coast, the ice is already breaking unp." "She is leading them into an increasingly dangerous new world." "It's unlikely both of her cubs will survive their first year out on the ice." "March, and munch of the north remains snow-bound." "A thousand miles south of the bears, stunted conifers are still locked in ice." "They mark the tree line of our planet and the start of the Taiga Forest." "This vast belt of trees forms an almost unbroken circle around the north of the globe." "It's one of the last great wildernesses." "These conifers have needle-shaped leaves - virtually inedible - so the forest supports very little animal life." "In this silent world, the snow is rarely marred by footprints, and those who do live here are so hard to glimpse, they're like spirits." "The lynx roams hundreds of miles in search of prey." "It may never visit the same patch of forest twice." "This creature is the very essence of wilderness." "There are as many trees here as in all the world's rain forests combined - one third of all the trees on Earth." "As spring creeps up from the south, the Taiga is unveiled." "It's now that this forest produces so munch oxygen that it refreshes the atmosphere of the entire planet." "April, and life starts returning to the far north." "Visitors flock to this haven from all over our planet." "They've come to make the most of the brief flush of spring food and to have their young." "In this changing world every new generation is precious." "Caribou travel north following the form - more than three million in vast herds crossing the tundra." "Some herds travel more than two thousand miles every year in search of fresh pasture." "It's the longest overland migration on Earth, totally dependant on vast open spaces." "They are constantly on the move." "If newborn calves are to keep up, they must be on their feet and running the day they're born." "but these vast herds don't travel alone." "Wolves shadow them all along the way..." "and they're hungry." "At first, the attack seems casual, random, but this running of the herd is a tactic to generate panic." "In the chaos, the young can be separated from their mothers." "Now it's easier to target an individual calf." "The calf may be young but it's capable of outrunning the wolf, if it manages to keep its footing." "By this stage, the odds are even." "Either the caribou will make a mistake, or after a mile or so, the wolf will give unp." "April in the Arctic, and already the sun never sets." "but further south, the sun works its magic in more gradual familiar ways." "These are the forests that we know well." "The broadleaf woodlands of Europe and North America." "More than any other, these have been crowded out by towns and farmland." "Only fragments remain." "Summers are longer here and deciduous trees can flourish." "They're far more edible than conifers, so these forests bustle with life." "Spring has also come early for the mandarin ducks." "The female is leaving her nest high in the treetops." "It's her job to lead the way." "It's a long way down for a maiden flight." "A few calls of encouragement are needed here." "There are still two missing." "Only two days old and already one great adventure behind them." "What will the rest of the year hold for our planet's latest recruits?" "This is the legacy we've inherited, thanks to that all-important tilt of the Earth's axis - the rhythm of the seasons." "The transformations of our world year on year," "a seasonal cycle that seems increasingly unreliable." "but there are parts of our world that have no seasons." "May, in the tropics, but there is no spring." "Here the sun shines for 12 hours a day every day of the year." "This is what allows the jungle to grow unchecked and support so munch life." "Rainforest now covers a third of the area it once did - a mere 3% of our planet's surface - and yet, it contains more than half of all the plants and animals on Earth." "The rain forests of New Guinea are especially precious - home to 42 different kinds of birds of paradise, each more extraordinary than the last." "This is a particularly rich forest, so the six-plumed bird of paradise has no problem finding food." "He can concentrate on more important tasks, like tidying up his display area." "He's obsessed with housework." "Everything has to be spick and span." "Finally, the stage is set." "It's a virtuoso performance." "Unfortunately, no-one was watching." "This contender is called the superb bird of paradise." "This magician has a special trick." "First, he advertises his show, calling to attract a female." "With the audience in place, the show can begin." "She just has to have been impressed with that." "She retires a little way off to consider her verdict." "After all that effort, can she still have doubts?" "You can't help feeling deflated when even your best wasn't good enough." "3% of our planet, 50% of its plants and animals - nowhere is there more at stake." "These tropical forests enjoy 12 hours of sunshine all year round, but they also need lots of rainfall." "As weather patterns change, there are already signs that these forests are starting to dry." "Deserts cover one third of the land's surface on Planet Earth, and they're getting bigger every year." "This is a land where only few can survive - only a special few " "and the challenges are becoming greater than ever." "June in the Kalahari Desert of Southern Africa." "It's the dry season here, and thousands of elephants have started the desperate trek for food and water." "Using ancient route-ways handed down through the generations, all are making their way to the Okavango, a vast inland delta in the heart of the desert." "At the moment it is dry, but water should come." "Buffalo join the great trek." "All across Southern Africa, millions of animals are on the move, on the same life or death quest for water." "This tiny calf struggles to keep up." "Its mother's instinct is to care for it, but her need for water is so desperate, she may be forced to leave it behind." "Dust storms make the going tough all the way." "They've become separated from the herd." "This is a dangerous place to lose your way." "There's sanctuary a few miles ahead - a small patch of woodland." "They daren't rest until they reach it." "The rest of the herd have escaped the storm, but they would all be at risk if they waited for the mother and the calf." "Finally, the stragglers emerge from the dust." "Blinded by sand, the calf barely has the strength to go on." "The storm has died down." "but not all the animals have been so lucky." "One youngster got lost." "Thirsty and exhausted, it follows the tracks of its mother, but in the wrong direction." "Where dust meets water, the march of the deserts is halted." "Sand dunes give way to prairies and savannah." "Grass is a great unsung hero of our planet." "It keeps deserts in check and fuels many of Earth's great spectacles." "The great game herds of East Africa all rely on this one miraculous plant." "Every day on wide open plains the world over, a timeless ritual plays itself out - the drama of hunter and hunted." "This is the circle of life that most of us, in our urban lives, have lost touch with." "The elephants have been marching now for two weeks." "The little calf and its mother have caught up with their herd, but they're desperately thirsty now." "Perhaps spurred on by a memory from the past, the matriarch leads the herd to a temporary water hole - one that may have saved her life years ago." "The elephants have to share the water with others." "These are uneasy alliances." "By day, the elephants dominate the water hole." "In the night time, the balance of power shifts." "The calf and its mother are most at risk." "They're closer to the lions than they can know." "In the darkness, an elephant's vision is little better than our own." "Lions can see easily." "The cats are ravenously hungry and the elephants sense the danger." "The lions bide their time." "It's the calves they're after." "As the lions rally, the elephants herd their young together, forming a protective circle to keep them away from the predators." "The cats have to find an opening in this defensive wall of hide." "The calves are too well protected." "The lions will have to take a risk, change their tactics." "Normally, a solitary lion would stand no chance against this elephant, but the whole pride is here - 30 of them - and they're specialist elephant hunters." "For the survivors, the Okavango Delta is still many miles away." "As the deserts grow, and traditional migration routes are blocked by farms and fences, elephants must trek ever greater distances." "The sun that scorches the desert also brings water to the land." "As it beats down on tropical seas, moisture rises from the warming oceans powering our global weather system." "Moist winds from the Indian oceans sweep north towards the Himalayas." "As the air rises, so it cools and the water falls as snow." "The scene is set for one of nature's most challenging migrations." "Each year, thousands of demoiselle cranes try to escape the harsh winters in Mongolia, by flying south to the warmer climes of India." "To get there, they have to cross the highest mountain range on Earth, the Himalayas." "As the sun heats these great slopes, warm air rises from the valleys, turning, by late morning, to ferocious winds." "The cranes hit violent turbulence." "They'll have to turn back or risk certain death." "The sun's rays weaken in the afternoon and the turbulence falls away, but it's too late for today." "A new day, a new chance." "The adults must guide their young on this hazardous trip." "It's early morning and the warm air is already rising fast." "They use the thermals to gain height." "Soon it'll get stormy again, maybe too stormy to go on." "In the final ascent, every wing beat is a desperate battle against the freezing winds." "At last, they've made it." "They've conquered the highest peaks on Earth." "On the other side there's sanctuary for the winter." "The sun melts the snow and the waters go on their way again - the start of their long journey back to the oceans." "This is the great unending cycle." "sunlight and fresh water bringing life to every corner of Planet Earth." "For generations, humans and animals alike come to depend on the great rivers and their seemingly endless flow." "After months of drought, the rivers begin to flow again in the Kalahari." "The buffalo reach the end of their long journey." "As the water sweeps through desert lands, the Okavango is transformed into a fertile paradise." "This is an Africa we rarely see - a lush water world totally reliant on a seasonal flood, originating from a tropical ocean thousands of miles away." "Many animals are quite at home in the flood, but there are some more apprehensive bathers." "After weeks of marching, the elephants are exhausted." "They struggle to stay focussed on the road ahead." "The matriarch can smell the water, and encourages the herd to make one last effort." "After so many weeks, many hundreds of miles, they've arrived." "Like the elephants, these waters have travelled great distances to reach here." "And all along the way, their flow is threatened by extraction for towns and farmland." "In its long life, the calf will make this journey many times." "Whether the flood will always arrive is far from certain." "The seasonal cycle that drives the lives of elephants on land, is just as important in the oceans." "It's July and the humpback whales are in their breeding grounds in the tropics." "This calf is no more than a few weeks old and as he begins to tire, his mother supports him close to the surface, so that he can breathe." "These shallow equatorial waters make good nurseries - they're warm and calm and there are few predators." "The playful calf is now drinking 600 litres of milk a day, but its mother is starving." "There's nothing for her to eat in these crystal clear waters." "To find food, she will have to lead her calf on an epic 4,000-mile journey to richer feeding grounds at the southern extremes of our planet." "This is the longest migration by any marine mammal, and it depends entirely on a healthy ocean all along the way." "out in the open ocean, the whales meet others searching for food." "Dolphins are closing in on their prey." "A hundred sailfish join in the attack." "Reaching almost 70 miles an hour, they are the cheetahs of the sea." "Mother and calf swim on south through the vast open oceans." "They have to cross half the globe, from the equator all the way to the edge of Antarctica." "The tropical seas are a long way behind them now." "They're heading for stormy seasonal waters." "Strong winds and currents draw nutrients up from the depths and life blooms wherever the sun's rays can penetrate." "The mother knows there are even richer feeding grounds further south, and hurries her calf through these dangerous waters." "The great white shark." "Great whites attack whale calves, but they're not the victims today." "These magnificent predators, at the very top of the food chain, are a vital part of a healthy ocean... and yet we slaughter almost a hundred million of them every year." "Their populations are in freefall." "August in the Arctic and the ice is vanishing fast." "The two cubs cannot cope with the shifting platform and their hungry mother is forced to lead them back to shore." "out to sea, the ice is now too thin to support the cubs' father." "Glacial melt waters pour from the land, mix with the sea, and speed up the thaw." "Each year, as the climate warms, there is less and less ice in the Arctic." "This is a disaster for polar bears." "Without a solid platform, they struggle to hunt the seals they need to survive." "How will the father make it through the year now that the ice is almost gone?" "September and the whales are 3,000 miles from the equator." "The waters are getting colder and rougher." "Mother and calf must stay close." "So as not to lose track of each other, they slap their fins on the surface." "They can hear these sound signals above the roar of the ocean." "The far south... at last." "October, and the whales are entering polar waters." "Summer is drawing to a close in the north, but here it is only just beginning." "As the sun melts the ice, life returns." "The whales have finally reached Antarctica in time for the summer." "Adelie penguins... and they're in a hurry to reach their nesting grounds." "December and the sun does not set." "The Antarctic summer is all too short, but for a few brief months its warmth unlocks sheltered bays." "In the depths, something stirs." "At last, after their 4,000-mile journey, the humpback whales can feed." "They harvest krill, shrimps that begin to swarm here as soon as the ice retreats." "Now, at last, the mother can replenish her reserves as she and her calf join the rest of the team." "The whales create a spiralling net of bubbles, concentrating the krill into one gigantic feast." "They work round the clock, for the boom will be short-lived." "Summer is fading fast and they'll soon have to return to tropical waters." "These whales, and most of the life in Antarctica, ultimately depend on krill." "Without it, the far south would be almost deserted." "but krill depend on ice and ice is in decline." "Winter in Antarctica and the greatest seasonal change on our planet is underway." "The sun begins to retreat." "Soon the continent will be plunged back into darkness." "The Aurora Australia illuminates the southern skies, but these spectacular lights bring no warmth to the wilderness of ice." "Back in the north of the planet, where our story began, the sea ice has completely disappeared." "our male polar bear is in great danger now." "If he doesn't find land soon in this vast ocean, he will drown." "After many days at sea, the exhausted bear is drawn by the pungent smells of the colony." "He has lost half his body weight." "He's desperate for food, but walrus are munch larger than his unseal prey." "It's the pups he'll have to get to." "The powerful adults can do terrible damage with their huge tusks." "The walrus sense the danger." "The adults close ranks around their young." "He tests the barrier." "It stands firm." "He may be the world's biggest land carnivore, but it looks like he's met his match and he's badly weakened by starvation." "A pup hides behind its mother." "If he can just prize her off." "With the herd retreating to the safety of the water, the bear has little time left." "He tries again." "And again, in sheer frustration now." "He has to avoid the lethal tusks at all costs." "It slips from his grasp." "It's only when bears are on the verge of starvation that they'll risk attacking such dangerous prey." "This one took the gamble... and lost." "The walrus are calm again." "The bear is no longer a threat." "Unable to feed, he can't survive." "As the global climate continues to warm, and the arctic ice melts sooner every year, more of his kind will come to this sad end." "A year has passed and the two bear cubs have beaten the odds." "They've left their mother... and are thriving." "Their ever-shifting world is changing faster by the day, but for now, they're keeping one step ahead." "Their father's adventurous spirit lives on in these magnificent youngsters - the next generation and proof of the resilience of life." "The polar bear has become an emblem for the state of our planet and for all the creatures who are struggling to live alongside uns." "Finally, we've begun to understand how precarious is the state of our once lucky planet." "If we are to go on sharing Earth with such a rich variety of life, and preserve its fragile balance for our own children, now, more than ever... it is in our hands."