1 00:00:47,333 --> 00:00:49,369 Of all the planets in our universe, 2 00:00:49,413 --> 00:00:52,849 there is only one we know can support life. 3 00:00:53,653 --> 00:00:57,885 just the right distance from its sun with a perfect climate. 4 00:00:58,693 --> 00:01:01,924 lt's been called the lucky planet. 5 00:01:06,813 --> 00:01:11,648 About five billion years ago, a huge asteroid crashed into Earth 6 00:01:11,693 --> 00:01:16,721 tilting it at an angle of exactly 23 and a half degrees to the sun. 7 00:01:19,213 --> 00:01:23,525 This cataclysmic accident turned out to be nothing short of a miracle. 8 00:01:24,933 --> 00:01:27,367 Without that crucial tilt, 9 00:01:27,413 --> 00:01:29,404 everything would have been different. 10 00:01:31,293 --> 00:01:37,243 For it created the seasons, the extremes of climate, hot and cold, 11 00:01:37,293 --> 00:01:40,285 and landscapes of spectacular beauty. 12 00:01:53,373 --> 00:01:57,286 The perfect conditions for life on Earth. 13 00:02:22,013 --> 00:02:26,484 All life on Earth is built on chance and powered by the sun. 14 00:02:27,733 --> 00:02:30,850 But the delicate balances of our world are faltering, 15 00:02:30,893 --> 00:02:34,568 as the planet struggles to support our growing demands. 16 00:02:35,573 --> 00:02:40,727 This is the time to take stock of what we have and what we stand to lose. 17 00:02:42,853 --> 00:02:44,764 We follow a year on Earth, 18 00:02:44,813 --> 00:02:48,567 joining our fellow creatures as they battle to raise their young 19 00:02:48,613 --> 00:02:51,411 in a world that is rapidly changing. 20 00:03:11,253 --> 00:03:14,165 January, the high Arctic, 21 00:03:14,213 --> 00:03:17,046 and there has been no sun for over a month. 22 00:03:18,053 --> 00:03:21,363 At this time of year, it's permanent night. 23 00:03:30,693 --> 00:03:35,209 Male polar bears are on winter patrol, but there is little to eat. 24 00:03:35,253 --> 00:03:36,652 (Bear grunting) 25 00:03:38,173 --> 00:03:41,085 Every living thing is just waiting. 26 00:04:20,293 --> 00:04:21,965 February, 27 00:04:22,013 --> 00:04:25,801 and the sun makes its first appearance over the horizon. 28 00:04:45,413 --> 00:04:49,486 This female bear has been underground in her den the whole winter. 29 00:04:52,133 --> 00:04:54,044 She toboggans down the slope. 30 00:04:55,893 --> 00:04:58,453 Perhaps it's just to clean her fur, 31 00:04:58,493 --> 00:05:00,882 but it looks like sheer joy. 32 00:05:09,573 --> 00:05:11,564 She hasn't been alone down there. 33 00:05:11,613 --> 00:05:14,411 Her cubs were born underground. 34 00:05:16,333 --> 00:05:17,732 (Mewling) 35 00:05:22,253 --> 00:05:23,527 They're two months old, 36 00:05:23,573 --> 00:05:26,963 but this is the very first time they've seen the light of day. 37 00:05:27,013 --> 00:05:28,207 (Mewling) 38 00:05:28,253 --> 00:05:30,608 (Soft grunts) 39 00:05:32,013 --> 00:05:33,002 (Mewling) 40 00:05:36,933 --> 00:05:39,128 They're drawn to their mother's calls, 41 00:05:40,133 --> 00:05:44,092 but these slopes are not the easiest place to take your first steps. 42 00:05:44,133 --> 00:05:45,122 (Mewling) 43 00:06:27,893 --> 00:06:30,965 The cubs haven't been fed this morning. 44 00:06:31,013 --> 00:06:34,608 The mother has delayed their first meal on this special day. 45 00:06:35,613 --> 00:06:38,047 Hunger will draw them to her. 46 00:06:38,093 --> 00:06:40,482 lt's the beginning of their training. 47 00:07:08,693 --> 00:07:11,287 Milk is the only food the cubs have known 48 00:07:11,333 --> 00:07:15,611 since they were born deaf and blind beneath the snow. 49 00:07:19,973 --> 00:07:22,487 The mother hasn't eaten for five months, 50 00:07:22,533 --> 00:07:24,922 and has lost half her body weight. 51 00:07:25,853 --> 00:07:28,970 She's giving the last of her reserves to her cubs. 52 00:07:29,013 --> 00:07:31,652 She can't leave yet in search of food. 53 00:07:31,693 --> 00:07:36,050 She's trapped on these slopes until the cubs find their feet. 54 00:07:37,653 --> 00:07:41,248 lt's a trial female bears have always endured. 55 00:07:46,373 --> 00:07:51,493 Every year at this time, female bears need food desperately. 56 00:07:51,533 --> 00:07:55,572 They know they must get down to their hunting grounds on the ice. 57 00:07:55,613 --> 00:08:01,165 What they can't know, is there's a problem waiting for them there. 58 00:08:01,213 --> 00:08:02,612 A new problem. 59 00:08:03,933 --> 00:08:08,882 our planet is warming and the sea ice is melting earlier every year. 60 00:08:08,933 --> 00:08:12,209 This is the only place the bears can hunt for seals. 61 00:08:12,253 --> 00:08:15,529 lf they don't make it there before the ice breaks up, 62 00:08:15,573 --> 00:08:17,962 their families will starve. 63 00:08:23,333 --> 00:08:26,370 So far this year, the ice holds firm, 64 00:08:26,413 --> 00:08:31,328 firm enough to support the male polar bear, the father of the cubs, 65 00:08:31,373 --> 00:08:33,682 as he searches for his prey. 66 00:08:35,133 --> 00:08:37,124 He won't help the female. 67 00:08:37,173 --> 00:08:40,483 lnstinct makes him fend for himself alone. 68 00:08:56,733 --> 00:08:58,166 Ten days later, 69 00:08:58,213 --> 00:09:02,252 and the starving mother is trying to lead her young down to the sea ice. 70 00:09:02,293 --> 00:09:04,284 They've found their feet now, 71 00:09:04,333 --> 00:09:07,962 but they still don't share her sense of urgency. 72 00:09:11,973 --> 00:09:13,167 (Soft barks) 73 00:09:15,093 --> 00:09:16,287 (Mewling) 74 00:09:37,293 --> 00:09:38,282 (Mewling) 75 00:10:03,253 --> 00:10:06,211 At last, everyone seems ready for the journey, 76 00:10:07,213 --> 00:10:09,522 but it may already be too late. 77 00:10:13,493 --> 00:10:15,484 (Cracking sounds) 78 00:10:20,813 --> 00:10:25,284 A few miles from the coast, the ice is already breaking unp. 79 00:10:55,893 --> 00:11:00,045 She is leading them into an increasingly dangerous new world. 80 00:11:01,013 --> 00:11:06,326 lt's unlikely both of her cubs will survive their first year out on the ice. 81 00:11:07,693 --> 00:11:09,684 (Cracking sounds) 82 00:11:11,853 --> 00:11:13,844 (Cracking sounds) 83 00:11:22,413 --> 00:11:25,007 March, and munch of the north remains snow-bound. 84 00:11:30,613 --> 00:11:33,081 A thousand miles south of the bears, 85 00:11:33,133 --> 00:11:36,250 stunted conifers are still locked in ice. 86 00:11:37,253 --> 00:11:42,725 They mark the tree line of our planet and the start of the Taiga Forest. 87 00:11:42,773 --> 00:11:48,769 This vast belt of trees forms an almost unbroken circle around the north of the globe. 88 00:11:48,813 --> 00:11:51,964 lt's one of the last great wildernesses. 89 00:11:58,293 --> 00:12:01,569 These conifers have needle-shaped leaves - 90 00:12:01,613 --> 00:12:03,410 virtually inedible - 91 00:12:03,453 --> 00:12:07,890 so the forest supports very little animal life. 92 00:12:14,813 --> 00:12:19,648 ln this silent world, the snow is rarely marred by footprints, 93 00:12:19,693 --> 00:12:25,529 and those who do live here are so hard to glimpse, they're like spirits. 94 00:12:40,333 --> 00:12:44,963 The lynx roams hundreds of miles in search of prey. 95 00:12:45,013 --> 00:12:48,483 lt may never visit the same patch of forest twice. 96 00:12:57,613 --> 00:13:01,686 This creature is the very essence of wilderness. 97 00:13:12,253 --> 00:13:17,566 There are as many trees here as in all the world's rain forests combined - 98 00:13:20,413 --> 00:13:24,531 one third of all the trees on Earth. 99 00:13:28,413 --> 00:13:33,646 As spring creeps up from the south, the Taiga is unveiled. 100 00:13:34,653 --> 00:13:37,963 lt's now that this forest produces so munch oxygen 101 00:13:38,013 --> 00:13:42,609 that it refreshes the atmosphere of the entire planet. 102 00:13:58,533 --> 00:14:02,606 April, and life starts returning to the far north. 103 00:14:10,453 --> 00:14:13,968 Visitors flock to this haven from all over our planet. 104 00:14:14,013 --> 00:14:18,131 They've come to make the most of the brief flush of spring food 105 00:14:18,173 --> 00:14:20,164 and to have their young. 106 00:14:27,158 --> 00:14:29,308 ln this changing world 107 00:14:29,358 --> 00:14:32,191 every new generation is precious. 108 00:14:44,878 --> 00:14:46,277 (Playful growling) 109 00:14:59,958 --> 00:15:03,348 Caribou travel north following the form - 110 00:15:03,398 --> 00:15:08,472 more than three million in vast herds crossing the tundra. 111 00:15:22,918 --> 00:15:27,196 Some herds travel more than two thousand miles every year 112 00:15:27,238 --> 00:15:29,229 in search of fresh pasture. 113 00:15:35,198 --> 00:15:38,270 lt's the longest overland migration on Earth, 114 00:15:38,318 --> 00:15:42,311 totally dependant on vast open spaces. 115 00:15:47,798 --> 00:15:50,187 They are constantly on the move. 116 00:15:50,238 --> 00:15:52,035 lf newborn calves are to keep up, 117 00:15:52,078 --> 00:15:55,753 they must be on their feet and running the day they're born. 118 00:16:25,158 --> 00:16:28,036 but these vast herds don't travel alone. 119 00:16:32,838 --> 00:16:37,832 Wolves shadow them all along the way... and they're hungry. 120 00:17:07,398 --> 00:17:10,549 At first, the attack seems casual, random, 121 00:17:10,598 --> 00:17:14,910 but this running of the herd is a tactic to generate panic. 122 00:17:19,398 --> 00:17:22,629 ln the chaos, the young can be separated from their mothers. 123 00:17:33,358 --> 00:17:36,555 Now it's easier to target an individual calf. 124 00:17:47,078 --> 00:17:50,673 The calf may be young but it's capable of outrunning the wolf, 125 00:17:50,718 --> 00:17:52,709 if it manages to keep its footing. 126 00:18:06,198 --> 00:18:08,154 By this stage, the odds are even. 127 00:18:08,198 --> 00:18:10,473 Either the caribou will make a mistake, 128 00:18:10,518 --> 00:18:13,396 or after a mile or so, the wolf will give unp. 129 00:18:56,278 --> 00:19:01,068 April in the Arctic, and already the sun never sets. 130 00:19:06,238 --> 00:19:12,347 but further south, the sun works its magic in more gradual familiar ways. 131 00:19:23,598 --> 00:19:25,190 (Birdsong) 132 00:19:33,558 --> 00:19:34,957 (Birdsong) 133 00:20:13,198 --> 00:20:15,758 These are the forests that we know well. 134 00:20:15,798 --> 00:20:19,234 The broadleaf woodlands of Europe and North America. 135 00:20:19,278 --> 00:20:24,955 More than any other, these have been crowded out by towns and farmland. 136 00:20:24,998 --> 00:20:26,989 Only fragments remain. 137 00:20:27,038 --> 00:20:28,630 (Birdsong) 138 00:20:37,598 --> 00:20:41,671 Summers are longer here and deciduous trees can flourish. 139 00:20:41,718 --> 00:20:44,630 They're far more edible than conifers, 140 00:20:44,678 --> 00:20:48,227 so these forests bustle with life. 141 00:20:53,718 --> 00:20:57,791 Spring has also come early for the mandarin ducks. 142 00:20:59,798 --> 00:21:02,551 The female is leaving her nest high in the treetops. 143 00:21:02,598 --> 00:21:04,668 lt's her job to lead the way. 144 00:21:09,598 --> 00:21:12,988 lt's a long way down for a maiden flight. 145 00:21:13,038 --> 00:21:14,027 (Quacks) 146 00:21:15,958 --> 00:21:18,552 A few calls of encouragement are needed here. 147 00:22:05,158 --> 00:22:07,149 There are still two missing. 148 00:22:33,478 --> 00:22:38,074 Only two days old and already one great adventure behind them. 149 00:22:39,078 --> 00:22:43,356 What will the rest of the year hold for our planet's latest recruits? 150 00:23:10,038 --> 00:23:12,506 This is the legacy we've inherited, 151 00:23:12,558 --> 00:23:17,348 thanks to that all-important tilt of the Earth's axis - 152 00:23:17,398 --> 00:23:19,389 the rhythm of the seasons. 153 00:23:44,318 --> 00:23:48,596 The transformations of our world year on year, 154 00:24:01,558 --> 00:24:05,631 a seasonal cycle that seems increasingly unreliable. 155 00:24:15,998 --> 00:24:19,229 but there are parts of our world that have no seasons. 156 00:24:41,078 --> 00:24:44,832 May, in the tropics, but there is no spring. 157 00:24:45,838 --> 00:24:50,912 Here the sun shines for 1 2 hours a day every day of the year. 158 00:24:50,958 --> 00:24:54,109 This is what allows the jungle to grow unchecked 159 00:24:54,158 --> 00:24:56,718 and support so munch life. 160 00:25:02,558 --> 00:25:06,437 Rainforest now covers a third of the area it once did - 161 00:25:06,478 --> 00:25:09,436 a mere 3% of our planet's surface - 162 00:25:09,478 --> 00:25:15,155 and yet, it contains more than half of all the plants and animals on Earth. 163 00:25:15,198 --> 00:25:17,348 (Bird and animal calls) 164 00:26:07,438 --> 00:26:09,633 (Bird and animal calls) 165 00:26:14,798 --> 00:26:18,234 The rain forests of New Guinea are especially precious - 166 00:26:18,278 --> 00:26:22,590 home to 42 different kinds of birds of paradise, 167 00:26:22,638 --> 00:26:25,232 each more extraordinary than the last. 168 00:26:30,438 --> 00:26:32,998 (Cawing) 169 00:26:35,958 --> 00:26:37,755 (Squeaking echoes) 170 00:26:53,838 --> 00:26:56,113 (Cawing) 171 00:26:56,718 --> 00:26:58,868 (Cawing) 172 00:27:06,798 --> 00:27:09,596 This is a particularly rich forest, 173 00:27:09,638 --> 00:27:14,029 so the six-plumed bird of paradise has no problem finding food. 174 00:27:14,078 --> 00:27:17,229 He can concentrate on more important tasks, 175 00:27:17,278 --> 00:27:19,314 like tidying up his display area. 176 00:27:20,478 --> 00:27:22,548 He's obsessed with housework. 177 00:27:23,198 --> 00:27:25,553 Everything has to be spick and span. 178 00:27:36,678 --> 00:27:38,748 Finally, the stage is set. 179 00:28:00,798 --> 00:28:03,187 lt's a virtuoso performance. 180 00:28:03,238 --> 00:28:06,150 Unfortunately, no-one was watching. 181 00:28:06,198 --> 00:28:08,189 (Cawing) 182 00:28:09,558 --> 00:28:13,312 This contender is called the superb bird of paradise. 183 00:28:14,118 --> 00:28:17,030 This magician has a special trick. 184 00:28:17,078 --> 00:28:19,831 First, he advertises his show, 185 00:28:19,878 --> 00:28:22,073 calling to attract a female. 186 00:28:24,038 --> 00:28:25,790 With the audience in place, 187 00:28:25,838 --> 00:28:27,476 the show can begin. 188 00:28:42,238 --> 00:28:44,957 She just has to have been impressed with that. 189 00:28:44,998 --> 00:28:48,308 She retires a little way off to consider her verdict. 190 00:28:50,518 --> 00:28:53,430 After all that effort, can she still have doubts? 191 00:28:56,398 --> 00:29:01,233 You can't help feeling deflated when even your best wasn't good enough. 192 00:29:05,918 --> 00:29:11,948 3% of our planet, 50% of its plants and animals - 193 00:29:13,398 --> 00:29:15,673 nowhere is there more at stake. 194 00:29:19,318 --> 00:29:23,630 These tropical forests enjoy 1 2 hours of sunshine all year round, 195 00:29:23,678 --> 00:29:26,636 but they also need lots of rainfall. 196 00:29:31,678 --> 00:29:34,988 As weather patterns change, there are already signs 197 00:29:35,038 --> 00:29:37,313 that these forests are starting to dry. 198 00:30:17,838 --> 00:30:19,635 (Howling wind) 199 00:30:37,318 --> 00:30:41,027 Deserts cover one third of the land's surface on Planet Earth, 200 00:30:41,078 --> 00:30:44,070 and they're getting bigger every year. 201 00:31:18,598 --> 00:31:21,749 This is a land where only few can survive - 202 00:31:21,798 --> 00:31:24,471 only a special few - 203 00:31:25,478 --> 00:31:28,276 and the challenges are becoming greater than ever. 204 00:31:47,118 --> 00:31:50,588 June in the Kalahari Desert of Southern Africa. 205 00:31:55,958 --> 00:31:57,357 (Trumpeting) 206 00:31:57,958 --> 00:31:59,949 lt's the dry season here, 207 00:31:59,998 --> 00:32:04,469 and thousands of elephants have started the desperate trek for food and water. 208 00:32:23,958 --> 00:32:28,270 Using ancient route-ways handed down through the generations, 209 00:32:28,318 --> 00:32:33,267 all are making their way to the Okavango, 210 00:32:33,318 --> 00:32:36,310 a vast inland delta in the heart of the desert. 211 00:32:37,318 --> 00:32:41,789 At the moment it is dry, but water should come. 212 00:32:46,758 --> 00:32:49,477 Buffalo join the great trek. 213 00:32:49,518 --> 00:32:53,670 All across Southern Africa, millions of animals are on the move, 214 00:32:53,718 --> 00:32:57,677 on the same life or death quest for water. 215 00:33:25,238 --> 00:33:28,355 This tiny calf struggles to keep unp. 216 00:33:29,078 --> 00:33:31,273 lts mother's instinct is to care for it, 217 00:33:31,318 --> 00:33:34,355 but her need for water is so desperate, 218 00:33:34,398 --> 00:33:37,117 she may be forced to leave it behind. 219 00:33:56,758 --> 00:34:00,307 Dust storms make the going tough all the way. 220 00:34:04,398 --> 00:34:05,626 (Trumpeting) 221 00:34:06,558 --> 00:34:09,630 They've become separated from the herd. 222 00:34:09,678 --> 00:34:12,317 This is a dangerous place to lose your way. 223 00:34:31,478 --> 00:34:35,391 There's sanctuary a few miles ahead - a small patch of woodland. 224 00:34:35,438 --> 00:34:38,111 They daren't rest until they reach it. 225 00:34:50,798 --> 00:34:53,312 The rest of the herd have escaped the storm, 226 00:34:53,358 --> 00:34:56,714 but they would all be at risk if they waited for the mother and the calf. 227 00:35:08,838 --> 00:35:11,989 Finally, the stragglers emerge from the dust. 228 00:35:20,598 --> 00:35:25,353 Blinded by sand, the calf barely has the strength to go on. 229 00:35:55,318 --> 00:35:57,229 The storm has died down. 230 00:35:59,318 --> 00:36:02,628 but not all the animals have been so lucky. 231 00:36:02,678 --> 00:36:05,033 One youngster got lost. 232 00:36:07,718 --> 00:36:14,794 Thirsty and exhausted, it follows the tracks of its mother, but in the wrong direction. 233 00:36:32,038 --> 00:36:36,429 Where dust meets water, the march of the deserts is halted. 234 00:36:41,558 --> 00:36:44,868 Sand dunes give way to prairies and savannah. 235 00:36:45,878 --> 00:36:49,666 Grass is a great unsung hero of our planet. 236 00:36:49,718 --> 00:36:55,668 lt keeps deserts in check and fuels many of Earth's great spectacles. 237 00:37:24,358 --> 00:37:30,035 The great game herds of East Africa all rely on this one miraculous plant. 238 00:38:03,118 --> 00:38:06,747 Every day on wide open plains the world over, 239 00:38:06,798 --> 00:38:10,029 a timeless ritual plays itself out - 240 00:38:10,078 --> 00:38:13,309 the drama of hunter and hunted. 241 00:38:52,118 --> 00:38:58,637 This is the circle of life that most of us, in our urban lives, have lost touch with. 242 00:40:51,238 --> 00:40:54,036 The elephants have been marching now for two weeks. 243 00:41:00,838 --> 00:41:04,467 The little calf and its mother have caught up with their herd, 244 00:41:04,518 --> 00:41:06,713 but they're desperately thirsty now. 245 00:41:17,078 --> 00:41:19,638 Perhaps spurred on by a memory from the past, 246 00:41:19,678 --> 00:41:23,466 the matriarch leads the herd to a temporary water hole - 247 00:41:23,518 --> 00:41:26,908 one that may have saved her life years ago. 248 00:42:15,598 --> 00:42:18,954 The elephants have to share the water with others. 249 00:42:18,998 --> 00:42:21,831 These are uneasy alliances. 250 00:42:30,918 --> 00:42:32,146 (Growls) 251 00:42:33,238 --> 00:42:34,227 (Trumpeting) 252 00:42:34,278 --> 00:42:35,267 (Growling) 253 00:42:39,398 --> 00:42:42,868 By day, the elephants dominate the water hole. 254 00:42:43,598 --> 00:42:44,997 (Thunder) 255 00:42:50,998 --> 00:42:54,673 ln the night time, the balance of power shifts. 256 00:42:58,358 --> 00:42:59,552 (Trumpeting) 257 00:43:02,758 --> 00:43:04,669 The calf and its mother are most at risk. 258 00:43:05,638 --> 00:43:08,277 They're closer to the lions than they can know. 259 00:43:14,758 --> 00:43:16,350 (Elephant growls) 260 00:43:17,478 --> 00:43:21,027 ln the darkness, an elephant's vision is little better than our own. 261 00:43:23,718 --> 00:43:26,312 Lions can see easily. 262 00:43:31,558 --> 00:43:33,116 (Elephant growls) 263 00:43:33,158 --> 00:43:34,671 (Lions growl) 264 00:43:36,798 --> 00:43:38,117 (Trumpets) 265 00:43:39,158 --> 00:43:41,353 The cats are ravenously hungry 266 00:43:41,398 --> 00:43:43,707 and the elephants sense the danger. 267 00:43:47,478 --> 00:43:48,593 (Elephant growls) 268 00:43:50,398 --> 00:43:51,592 (Trumpeting) 269 00:43:55,478 --> 00:43:56,467 (Elephant growls) 270 00:43:56,518 --> 00:43:58,509 The lions bide their time. 271 00:44:07,478 --> 00:44:09,912 lt's the calves they're after. 272 00:44:20,398 --> 00:44:21,797 (Elephant growls) 273 00:44:34,438 --> 00:44:35,996 (Squealing and growling) 274 00:44:41,718 --> 00:44:43,117 (Lions growling) 275 00:44:43,158 --> 00:44:46,867 As the lions rally, the elephants herd their young together, 276 00:44:46,918 --> 00:44:50,672 forming a protective circle to keep them away from the predators. 277 00:45:03,678 --> 00:45:07,990 The cats have to find an opening in this defensive wall of hide. 278 00:45:12,918 --> 00:45:14,556 (Elephants growl) 279 00:45:23,278 --> 00:45:24,552 (Lion growls) 280 00:45:25,998 --> 00:45:27,192 (Trumpeting) 281 00:45:37,078 --> 00:45:39,638 (Growls) 282 00:45:45,678 --> 00:45:47,987 (Growling) 283 00:45:51,158 --> 00:45:52,955 (All lions growling) 284 00:46:02,718 --> 00:46:04,788 The calves are too well protected. 285 00:46:04,838 --> 00:46:09,070 The lions will have to take a risk, change their tactics. 286 00:46:11,518 --> 00:46:15,830 Normally, a solitary lion would stand no chance against this elephant, 287 00:46:15,878 --> 00:46:19,314 but the whole pride is here - 30 of them - 288 00:46:19,358 --> 00:46:21,918 and they're specialist elephant hunters. 289 00:46:23,998 --> 00:46:26,068 (Elephant growls) 290 00:46:32,158 --> 00:46:33,750 (Elephant growls) 291 00:46:46,318 --> 00:46:47,910 (Elephant squeals) 292 00:46:53,558 --> 00:46:54,957 (Thunderclap ) 293 00:47:07,798 --> 00:47:12,633 For the survivors, the Okavango Delta is still many miles away. 294 00:47:25,798 --> 00:47:31,794 As the deserts grow, and traditional migration routes are blocked by farms and fences, 295 00:47:31,838 --> 00:47:34,910 elephants must trek ever greater distances. 296 00:47:46,078 --> 00:47:50,754 The sun that scorches the desert also brings water to the land. 297 00:47:51,678 --> 00:47:54,272 As it beats down on tropical seas, 298 00:47:54,318 --> 00:47:59,597 moisture rises from the warming oceans powering our global weather system. 299 00:48:46,478 --> 00:48:51,347 Moist winds from the Indian oceans sweep north towards the Himalayas. 300 00:48:53,838 --> 00:48:58,866 As the air rises, so it cools and the water falls as snow. 301 00:49:13,158 --> 00:49:17,197 The scene is set for one of nature’s most challenging migrations. 302 00:49:20,718 --> 00:49:26,953 Each year, thousands of demoiselle cranes try to escape the harsh winters in Mongolia, 303 00:49:26,998 --> 00:49:30,786 by flying south to the warmer climes of lndia. 304 00:49:37,798 --> 00:49:42,474 To get there, they have to cross the highest mountain range on Earth, 305 00:49:43,478 --> 00:49:45,070 the Himalayas. 306 00:49:57,798 --> 00:50:02,872 As the sun heats these great slopes, warm air rises from the valleys, 307 00:50:02,918 --> 00:50:06,706 turning, by late morning, to ferocious winds. 308 00:50:20,238 --> 00:50:22,832 The cranes hit violent turbulence. 309 00:50:26,478 --> 00:50:30,517 They'll have to turn back or risk certain death. 310 00:51:02,678 --> 00:51:07,627 The sun's rays weaken in the afternoon and the turbulence falls away, 311 00:51:07,678 --> 00:51:09,714 but it's too late for today. 312 00:51:41,478 --> 00:51:44,038 A new day, a new chance. 313 00:51:45,038 --> 00:51:48,553 The adults must guide their young on this hazardous trip. 314 00:51:55,558 --> 00:52:00,029 lt's early morning and the warm air is already rising fast. 315 00:52:00,078 --> 00:52:03,354 They use the thermals to gain height. 316 00:52:13,078 --> 00:52:16,957 Soon it'll get stormy again, maybe too stormy to go on. 317 00:52:35,878 --> 00:52:42,397 ln the final ascent, every wing beat is a desperate battle against the freezing winds. 318 00:53:10,278 --> 00:53:15,272 At last, they've made it. They've conquered the highest peaks on Earth. 319 00:53:16,758 --> 00:53:20,910 On the other side there's sanctuary for the winter. 320 00:53:40,478 --> 00:53:44,835 The sun melts the snow and the waters go on their way again - 321 00:53:45,838 --> 00:53:49,035 the start of their long journey back to the oceans. 322 00:54:49,038 --> 00:54:51,472 This is the great unending cycle. 323 00:54:51,518 --> 00:54:56,956 sunlight and fresh water bringing life to every corner of Planet Earth. 324 00:55:25,238 --> 00:55:28,833 For generations, humans and animals alike 325 00:55:28,878 --> 00:55:33,633 come to depend on the great rivers and their seemingly endless flow. 326 00:56:45,638 --> 00:56:50,189 After months of drought, the rivers begin to flow again in the Kalahari. 327 00:56:50,238 --> 00:56:53,708 The buffalo reach the end of their long journey. 328 00:57:00,678 --> 00:57:03,272 As the water sweeps through desert lands, 329 00:57:03,318 --> 00:57:07,755 the Okavango is transformed into a fertile paradise. 330 00:57:29,798 --> 00:57:32,551 This is an Africa we rarely see - 331 00:57:32,598 --> 00:57:37,797 a lush water world totally reliant on a seasonal flood, 332 00:57:37,838 --> 00:57:42,593 originating from a tropical ocean thousands of miles away. 333 00:58:02,278 --> 00:58:04,746 Many animals are quite at home in the flood, 334 00:58:04,798 --> 00:58:08,427 but there are some more apprehensive bathers. 335 00:58:13,118 --> 00:58:14,312 (Grumbling) 336 00:58:19,918 --> 00:58:21,397 (Squeaking) 337 00:58:29,198 --> 00:58:30,187 (Grunts) 338 00:58:34,718 --> 00:58:35,707 (Grunts) 339 00:58:42,438 --> 00:58:43,427 (Squeaks) 340 00:58:46,358 --> 00:58:47,347 (Squeaks) 341 00:59:19,838 --> 00:59:24,150 After weeks of marching, the elephants are exhausted. 342 00:59:25,158 --> 00:59:27,991 They struggle to stay focussed on the road ahead. 343 00:59:37,518 --> 00:59:39,156 (Soft growls) 344 00:59:39,198 --> 00:59:40,597 (Calf squeaks) 345 00:59:45,278 --> 00:59:47,667 The matriarch can smell the water, 346 00:59:47,718 --> 00:59:51,313 and encourages the herd to make one last effort. 347 00:59:53,238 --> 00:59:54,432 (Calf squeals) 348 01:00:22,358 --> 01:00:24,394 After so many weeks, 349 01:00:24,438 --> 01:00:27,555 many hundreds of miles, 350 01:00:27,598 --> 01:00:29,395 they've arrived. 351 01:00:30,398 --> 01:00:31,797 (Trumpeting) 352 01:00:32,758 --> 01:00:34,555 (Trumpeting) 353 01:00:57,718 --> 01:00:59,117 (Trumpeting) 354 01:01:15,798 --> 01:01:17,197 (Trumpeting) 355 01:01:29,038 --> 01:01:30,027 (Soft growls) 356 01:01:34,438 --> 01:01:39,796 Like the elephants, these waters have travelled great distances to reach here. 357 01:01:40,958 --> 01:01:46,510 And all along the way, their flow is threatened by extraction for towns and farmland. 358 01:01:47,518 --> 01:01:51,875 ln its long life, the calf will make this journey many times. 359 01:01:53,398 --> 01:01:57,914 Whether the flood will always arrive is far from certain. 360 01:02:16,158 --> 01:02:20,231 The seasonal cycle that drives the lives of elephants on land, 361 01:02:20,278 --> 01:02:23,634 is just as important in the oceans. 362 01:02:46,158 --> 01:02:48,149 (Whale song) 363 01:03:10,398 --> 01:03:15,836 lt's July and the humpback whales are in their breeding grounds in the tropics. 364 01:03:35,438 --> 01:03:38,236 This calf is no more than a few weeks old 365 01:03:38,278 --> 01:03:40,348 and as he begins to tire, 366 01:03:40,398 --> 01:03:44,789 his mother supports him close to the surface, so that he can breathe. 367 01:04:04,278 --> 01:04:07,827 These shallow equatorial waters make good nurseries - 368 01:04:07,878 --> 01:04:11,666 they're warm and calm and there are few predators. 369 01:04:26,198 --> 01:04:31,397 The playful calf is now drinking 600 litres of milk a day, 370 01:04:31,438 --> 01:04:33,429 but its mother is starving. 371 01:04:33,478 --> 01:04:37,187 There's nothing for her to eat in these crystal clear waters. 372 01:04:57,958 --> 01:05:03,874 To find food, she will have to lead her calf on an epic 4,000-mile journey 373 01:05:03,918 --> 01:05:08,673 to richer feeding grounds at the southern extremes of our planet. 374 01:05:13,198 --> 01:05:16,747 This is the longest migration by any marine mammal, 375 01:05:16,798 --> 01:05:21,553 and it depends entirely on a healthy ocean all along the way. 376 01:05:50,678 --> 01:05:54,990 out in the open ocean, the whales meet others searching for food. 377 01:06:05,958 --> 01:06:08,426 Dolphins are closing in on their prey. 378 01:06:16,998 --> 01:06:19,592 A hundred sailfish join in the attack. 379 01:06:23,398 --> 01:06:27,835 Reaching almost 70 miles an hour, they are the cheetahs of the sea. 380 01:07:12,038 --> 01:07:16,554 Mother and calf swim on south through the vast open oceans. 381 01:07:16,598 --> 01:07:18,509 They have to cross half the globe, 382 01:07:18,558 --> 01:07:22,631 from the equator all the way to the edge of Antarctica. 383 01:07:31,478 --> 01:07:34,276 The tropical seas are a long way behind them now. 384 01:07:34,318 --> 01:07:37,196 They're heading for stormy seasonal waters. 385 01:07:38,398 --> 01:07:42,994 Strong winds and currents draw nutrients up from the depths 386 01:07:43,038 --> 01:07:47,077 and life blooms wherever the sun's rays can penetrate. 387 01:08:34,078 --> 01:08:37,787 The mother knows there are even richer feeding grounds further south, 388 01:08:37,838 --> 01:08:41,717 and hurries her calf through these dangerous waters. 389 01:08:57,798 --> 01:08:59,789 The great white shark. 390 01:09:12,078 --> 01:09:14,433 Great whites attack whale calves, 391 01:09:15,438 --> 01:09:17,668 but they're not the victims today. 392 01:10:24,158 --> 01:10:28,674 These magnificent predators, at the very top of the food chain, 393 01:10:28,718 --> 01:10:31,790 are a vital part of a healthy ocean... 394 01:10:32,798 --> 01:10:37,076 and yet we slaughter almost a hundred million of them every year. 395 01:10:38,638 --> 01:10:41,232 Their populations are in freefall. 396 01:11:10,318 --> 01:11:11,910 (Creaking) 397 01:11:21,958 --> 01:11:26,588 August in the Arctic and the ice is vanishing fast. 398 01:11:27,638 --> 01:11:30,675 The two cubs cannot cope with the shifting platform 399 01:11:30,718 --> 01:11:34,233 and their hungry mother is forced to lead them back to shore. 400 01:11:39,398 --> 01:11:40,797 (Soft growls) 401 01:11:47,038 --> 01:11:52,317 out to sea, the ice is now too thin to support the cubs' father. 402 01:12:12,958 --> 01:12:18,351 Glacial melt waters pour from the land, mix with the sea, and speed up the thaw. 403 01:12:29,318 --> 01:12:34,153 Each year, as the climate warms, there is less and less ice in the Arctic. 404 01:12:35,158 --> 01:12:38,036 This is a disaster for polar bears. 405 01:12:38,078 --> 01:12:43,198 Without a solid platform, they struggle to hunt the seals they need to survive. 406 01:12:54,318 --> 01:12:55,433 (Growls) 407 01:13:00,238 --> 01:13:01,227 (Growls) 408 01:13:18,078 --> 01:13:22,629 How will the father make it through the year now that the ice is almost gone? 409 01:13:29,518 --> 01:13:33,477 September and the whales are 3,000 miles from the equator. 410 01:13:33,518 --> 01:13:36,908 The waters are getting colder and rougher. 411 01:13:37,918 --> 01:13:40,148 Mother and calf must stay close. 412 01:13:49,118 --> 01:13:53,475 So as not to lose track of each other, they slap their fins on the surface. 413 01:13:53,518 --> 01:13:57,557 They can hear these sound signals above the roar of the ocean. 414 01:14:35,158 --> 01:14:37,797 The far south...at last. 415 01:14:56,078 --> 01:15:00,310 October, and the whales are entering polar waters. 416 01:15:00,358 --> 01:15:05,591 Summer is drawing to a close in the north, but here it is only just beginning. 417 01:15:17,438 --> 01:15:21,556 As the sun melts the ice, life returns. 418 01:15:34,478 --> 01:15:39,950 The whales have finally reached Antarctica in time for the summer. 419 01:15:44,518 --> 01:15:46,315 Adelie penguins... 420 01:15:47,198 --> 01:15:50,395 and they're in a hurry to reach their nesting grounds. 421 01:16:18,198 --> 01:16:21,031 December and the sun does not set. 422 01:16:26,118 --> 01:16:28,996 The Antarctic summer is all too short, 423 01:16:29,038 --> 01:16:34,351 but for a few brief months its warmth unlocks sheltered bays. 424 01:16:49,678 --> 01:16:52,556 ln the depths, something stirs. 425 01:17:19,718 --> 01:17:25,827 At last, after their 4,000-mile journey, the humpback whales can feed. 426 01:17:34,678 --> 01:17:40,947 They harvest krill, shrimps that begin to swarm here as soon as the ice retreats. 427 01:17:55,438 --> 01:17:58,714 Now, at last, the mother can replenish her reserves 428 01:17:58,758 --> 01:18:02,467 as she and her calf join the rest of the team. 429 01:18:08,278 --> 01:18:11,748 The whales create a spiralling net of bubbles, 430 01:18:11,798 --> 01:18:15,473 concentrating the krill into one gigantic feast. 431 01:18:26,638 --> 01:18:29,789 They work round the clock, for the boom will be short-lived. 432 01:18:29,838 --> 01:18:35,356 Summer is fading fast and they'll soon have to return to tropical waters. 433 01:18:40,998 --> 01:18:46,834 These whales, and most of the life in Antarctica, ultimately depend on krill. 434 01:18:47,838 --> 01:18:51,877 Without it, the far south would be almost deserted. 435 01:18:53,158 --> 01:18:57,993 but krill depend on ice and ice is in decline. 436 01:19:08,438 --> 01:19:10,633 Winter in Antarctica 437 01:19:10,678 --> 01:19:14,034 and the greatest seasonal change on our planet is underway. 438 01:19:32,918 --> 01:19:35,227 The sun begins to retreat. 439 01:19:37,118 --> 01:19:41,031 Soon the continent will be plunged back into darkness. 440 01:19:49,758 --> 01:19:54,957 The Aurora Australia illuminates the southern skies, 441 01:19:54,998 --> 01:20:00,709 but these spectacular lights bring no warmth to the wilderness of ice. 442 01:20:36,958 --> 01:20:40,507 Back in the north of the planet, where our story began, 443 01:20:40,558 --> 01:20:43,994 the sea ice has completely disappeared. 444 01:21:00,158 --> 01:21:02,718 our male polar bear is in great danger now. 445 01:21:04,438 --> 01:21:08,989 lf he doesn't find land soon in this vast ocean, he will drown. 446 01:21:34,238 --> 01:21:36,229 (Grunts and growls) 447 01:21:56,598 --> 01:21:58,475 After many days at sea, 448 01:21:58,518 --> 01:22:03,512 the exhausted bear is drawn by the pungent smells of the colony. 449 01:22:13,918 --> 01:22:16,512 He has lost half his body weight. 450 01:22:16,558 --> 01:22:18,833 He's desperate for food, 451 01:22:18,878 --> 01:22:22,234 but walrus are munch larger than his unseal prey. 452 01:22:27,998 --> 01:22:29,989 lt's the pups he'll have to get to. 453 01:22:30,038 --> 01:22:34,589 The powerful adults can do terrible damage with their huge tusks. 454 01:22:38,798 --> 01:22:40,789 (Grunting and growling) 455 01:23:13,158 --> 01:23:15,274 The walrus sense the danger. 456 01:23:16,358 --> 01:23:18,667 The adults close ranks around their young. 457 01:23:21,718 --> 01:23:23,390 He tests the barrier. 458 01:23:26,998 --> 01:23:28,351 lt stands firm. 459 01:23:31,758 --> 01:23:34,226 He may be the world's biggest land carnivore, 460 01:23:34,278 --> 01:23:39,147 but it looks like he's met his match and he's badly weakened by starvation. 461 01:23:47,558 --> 01:23:49,833 A pup hides behind its mother. 462 01:23:52,998 --> 01:23:55,228 lf he can just prize her off. 463 01:24:18,158 --> 01:24:20,513 With the herd retreating to the safety of the water, 464 01:24:20,558 --> 01:24:22,469 the bear has little time left. 465 01:24:25,438 --> 01:24:26,666 He tries again. 466 01:24:26,718 --> 01:24:27,912 (Growling) 467 01:24:29,238 --> 01:24:31,035 (Walrus growls) 468 01:24:38,598 --> 01:24:41,317 And again, in sheer frustration now. 469 01:25:11,278 --> 01:25:14,793 He has to avoid the lethal tusks at all costs. 470 01:25:14,838 --> 01:25:16,237 (Walrus growls) 471 01:25:17,758 --> 01:25:19,157 (Howls) 472 01:25:40,758 --> 01:25:42,988 lt slips from his grasp. 473 01:25:59,198 --> 01:26:02,156 lt's only when bears are on the verge of starvation 474 01:26:02,198 --> 01:26:05,429 that they'll risk attacking such dangerous prey. 475 01:26:16,278 --> 01:26:17,267 (Grunts) 476 01:26:17,318 --> 01:26:19,673 This one took the gamble...and lost. 477 01:26:37,478 --> 01:26:39,469 The walrus are calm again. 478 01:26:40,678 --> 01:26:42,669 The bear is no longer a threat. 479 01:26:46,278 --> 01:26:50,112 Unable to feed, he can't survive. 480 01:27:05,238 --> 01:27:08,116 As the global climate continues to warm, 481 01:27:08,158 --> 01:27:11,514 and the arctic ice melts sooner every year, 482 01:27:11,558 --> 01:27:14,948 more of his kind will come to this sad end. 483 01:27:38,198 --> 01:27:42,510 A year has passed and the two bear cubs have beaten the odds. 484 01:27:49,198 --> 01:27:52,315 They've left their mother...and are thriving. 485 01:28:22,238 --> 01:28:26,436 Their ever-shifting world is changing faster by the day, 486 01:28:26,478 --> 01:28:30,107 but for now, they're keeping one step ahead. 487 01:28:31,278 --> 01:28:36,511 Their father's adventurous spirit lives on in these magnificent youngsters - 488 01:28:37,598 --> 01:28:42,114 the next generation and proof of the resilience of life. 489 01:29:11,798 --> 01:29:16,269 The polar bear has become an emblem for the state of our planet 490 01:29:16,318 --> 01:29:19,993 and for all the creatures who are struggling to live alongside uns. 491 01:29:52,398 --> 01:29:54,958 Finally, we've begun to understand 492 01:29:54,998 --> 01:30:00,152 how precarious is the state of our once lucky planet. 493 01:30:01,878 --> 01:30:06,668 lf we are to go on sharing Earth with such a rich variety of life, 494 01:30:06,718 --> 01:30:10,870 and preserve its fragile balance for our own children, 495 01:30:10,918 --> 01:30:12,909 now, more than ever... 496 01:30:14,038 --> 01:30:16,029 it is in our hands.