1 00:00:49,333 --> 00:00:51,456 Of all the planets in our universe, 2 00:00:51,502 --> 00:00:55,085 there is only one we know can support life. 3 00:00:55,923 --> 00:01:00,336 just the right distance from its sun with a perfect climate. 4 00:01:01,179 --> 00:01:04,548 lt's been called the lucky planet. 5 00:01:09,647 --> 00:01:14,689 About five billion years ago, a huge asteroid crashed into Earth 6 00:01:14,736 --> 00:01:19,979 tilting it at an angle of exactly 23 and a half degrees to the sun. 7 00:01:22,579 --> 00:01:27,075 This cataclysmic accident turned out to be nothing short of a miracle. 8 00:01:28,544 --> 00:01:31,082 Without that crucial tilt, 9 00:01:31,130 --> 00:01:33,206 everything would have been different. 10 00:01:35,176 --> 00:01:41,380 For it created the seasons, the extremes of climate, hot and cold, 11 00:01:41,434 --> 00:01:44,554 and landscapes of spectacular beauty. 12 00:01:58,203 --> 00:02:02,283 The perfect conditions for life on Earth. 13 00:02:28,070 --> 00:02:32,732 All life on Earth is built on chance and powered by the sun. 14 00:02:34,035 --> 00:02:37,285 But the delicate balances of our world are faltering, 15 00:02:37,331 --> 00:02:41,163 as the planet struggles to support our growing demands. 16 00:02:42,211 --> 00:02:47,585 This is the time to take stock of what we have and what we stand to lose. 17 00:02:49,803 --> 00:02:51,795 We follow a year on Earth, 18 00:02:51,847 --> 00:02:55,761 joining our fellow creatures as they battle to raise their young 19 00:02:55,810 --> 00:02:58,727 in a world that is rapidly changing. 20 00:03:19,420 --> 00:03:22,456 January, the high Arctic, 21 00:03:22,507 --> 00:03:25,461 and there has been no sun for over a month. 22 00:03:26,512 --> 00:03:29,963 At this time of year, it's permanent night. 23 00:03:39,694 --> 00:03:44,403 Male polar bears are on winter patrol, but there is little to eat. 24 00:03:44,449 --> 00:03:45,907 (Bear grunting) 25 00:03:47,494 --> 00:03:50,530 Every living thing is just waiting. 26 00:04:31,419 --> 00:04:33,162 February, 27 00:04:33,213 --> 00:04:37,163 and the sun makes its first appearance over the horizon. 28 00:04:57,616 --> 00:05:01,863 This female bear has been underground in her den the whole winter. 29 00:05:04,624 --> 00:05:06,616 She toboggans down the slope. 30 00:05:08,545 --> 00:05:11,214 Perhaps it's just to clean her fur, 31 00:05:11,256 --> 00:05:13,747 but it looks like sheer joy. 32 00:05:22,811 --> 00:05:24,887 She hasn't been alone down there. 33 00:05:24,939 --> 00:05:27,856 Her cubs were born underground. 34 00:05:29,861 --> 00:05:31,319 (Mewling) 35 00:05:36,035 --> 00:05:37,363 They're two months old, 36 00:05:37,411 --> 00:05:40,946 but this is the very first time they've seen the light of day. 37 00:05:40,999 --> 00:05:42,244 (Mewling) 38 00:05:42,292 --> 00:05:44,747 (Soft grunts) 39 00:05:46,213 --> 00:05:47,244 (Mewling) 40 00:05:51,344 --> 00:05:53,633 They're drawn to their mother's calls, 41 00:05:54,681 --> 00:05:58,809 but these slopes are not the easiest place to take your first steps. 42 00:05:58,852 --> 00:05:59,883 (Mewling) 43 00:06:44,488 --> 00:06:47,691 The cubs haven't been fed this morning. 44 00:06:47,742 --> 00:06:51,491 The mother has delayed their first meal on this special day. 45 00:06:52,539 --> 00:06:55,077 Hunger will draw them to her. 46 00:06:55,125 --> 00:06:57,616 lt's the beginning of their training. 47 00:07:27,036 --> 00:07:29,741 Milk is the only food the cubs have known 48 00:07:29,790 --> 00:07:34,251 since they were born deaf and blind beneath the snow. 49 00:07:38,800 --> 00:07:41,421 The mother hasn't eaten for five months, 50 00:07:41,470 --> 00:07:43,961 and has lost half her body weight. 51 00:07:44,932 --> 00:07:48,182 She's giving the last of her reserves to her cubs. 52 00:07:48,227 --> 00:07:50,979 She can't leave yet in search of food. 53 00:07:51,022 --> 00:07:55,565 She's trapped on these slopes until the cubs find their feet. 54 00:07:57,238 --> 00:08:00,987 lt's a trial female bears have always endured. 55 00:08:06,331 --> 00:08:11,670 Every year at this time, female bears need food desperately. 56 00:08:11,712 --> 00:08:15,924 They know they must get down to their hunting grounds on the ice. 57 00:08:15,967 --> 00:08:21,756 What they can't know, is there's a problem waiting for them there. 58 00:08:21,807 --> 00:08:23,265 A new problem. 59 00:08:24,644 --> 00:08:29,805 our planet is warming and the sea ice is melting earlier every year. 60 00:08:29,858 --> 00:08:33,274 This is the only place the bears can hunt for seals. 61 00:08:33,320 --> 00:08:36,736 lf they don't make it there before the ice breaks up, 62 00:08:36,783 --> 00:08:39,274 their families will starve. 63 00:08:44,875 --> 00:08:48,042 So far this year, the ice holds firm, 64 00:08:48,087 --> 00:08:53,212 firm enough to support the male polar bear, the father of the cubs, 65 00:08:53,260 --> 00:08:55,667 as he searches for his prey. 66 00:08:57,181 --> 00:08:59,257 He won't help the female. 67 00:08:59,308 --> 00:09:02,759 lnstinct makes him fend for himself alone. 68 00:09:19,707 --> 00:09:21,201 Ten days later, 69 00:09:21,250 --> 00:09:25,462 and the starving mother is trying to lead her young down to the sea ice. 70 00:09:25,505 --> 00:09:27,581 They've found their feet now, 71 00:09:27,632 --> 00:09:31,416 but they still don't share her sense of urgency. 72 00:09:35,600 --> 00:09:36,845 (Soft barks) 73 00:09:38,853 --> 00:09:40,098 (Mewling) 74 00:10:02,005 --> 00:10:03,036 (Mewling) 75 00:10:29,077 --> 00:10:32,161 At last, everyone seems ready for the journey, 76 00:10:33,207 --> 00:10:35,614 but it may already be too late. 77 00:10:39,756 --> 00:10:41,832 (Cracking sounds) 78 00:10:47,390 --> 00:10:52,052 A few miles from the coast, the ice is already breaking unp. 79 00:11:23,973 --> 00:11:28,302 She is leading them into an increasingly dangerous new world. 80 00:11:29,313 --> 00:11:34,853 lt's unlikely both of her cubs will survive their first year out on the ice. 81 00:11:36,279 --> 00:11:38,355 (Cracking sounds) 82 00:11:40,617 --> 00:11:42,693 (Cracking sounds) 83 00:11:51,630 --> 00:11:54,335 March, and munch of the north remains snow-bound. 84 00:12:00,181 --> 00:12:02,754 A thousand miles south of the bears, 85 00:12:02,809 --> 00:12:06,059 stunted conifers are still locked in ice. 86 00:12:07,106 --> 00:12:12,812 They mark the tree line of our planet and the start of the Taiga Forest. 87 00:12:12,863 --> 00:12:19,115 This vast belt of trees forms an almost unbroken circle around the north of the globe. 88 00:12:19,161 --> 00:12:22,447 lt's one of the last great wildernesses. 89 00:12:29,048 --> 00:12:32,464 These conifers have needle-shaped leaves - 90 00:12:32,510 --> 00:12:34,384 virtually inedible - 91 00:12:34,429 --> 00:12:39,056 so the forest supports very little animal life. 92 00:12:46,276 --> 00:12:51,318 ln this silent world, the snow is rarely marred by footprints, 93 00:12:51,365 --> 00:12:57,451 and those who do live here are so hard to glimpse, they're like spirits. 94 00:13:12,889 --> 00:13:17,717 The lynx roams hundreds of miles in search of prey. 95 00:13:17,770 --> 00:13:21,388 lt may never visit the same patch of forest twice. 96 00:13:30,910 --> 00:13:35,157 This creature is the very essence of wilderness. 97 00:13:46,177 --> 00:13:51,717 There are as many trees here as in all the world's rain forests combined - 98 00:13:54,687 --> 00:13:58,981 one third of all the trees on Earth. 99 00:14:03,030 --> 00:14:08,487 As spring creeps up from the south, the Taiga is unveiled. 100 00:14:09,537 --> 00:14:12,988 lt's now that this forest produces so munch oxygen 101 00:14:13,041 --> 00:14:17,833 that it refreshes the atmosphere of the entire planet. 102 00:14:34,441 --> 00:14:38,688 April, and life starts returning to the far north. 103 00:14:46,872 --> 00:14:50,537 Visitors flock to this haven from all over our planet. 104 00:14:50,584 --> 00:14:54,878 They've come to make the most of the brief flush of spring food 105 00:14:54,923 --> 00:14:56,999 and to have their young. 106 00:15:04,293 --> 00:15:06,535 ln this changing world 107 00:15:06,587 --> 00:15:09,541 every new generation is precious. 108 00:15:22,772 --> 00:15:24,230 (Playful growling) 109 00:15:38,498 --> 00:15:42,033 Caribou travel north following the form - 110 00:15:42,086 --> 00:15:47,377 more than three million in vast herds crossing the tundra. 111 00:16:02,442 --> 00:16:06,903 Some herds travel more than two thousand miles every year 112 00:16:06,947 --> 00:16:09,023 in search of fresh pasture. 113 00:16:15,249 --> 00:16:18,452 lt's the longest overland migration on Earth, 114 00:16:18,502 --> 00:16:22,666 totally dependant on vast open spaces. 115 00:16:28,389 --> 00:16:30,880 They are constantly on the move. 116 00:16:30,933 --> 00:16:32,807 lf newborn calves are to keep up, 117 00:16:32,852 --> 00:16:36,684 they must be on their feet and running the day they're born. 118 00:17:07,350 --> 00:17:10,351 but these vast herds don't travel alone. 119 00:17:15,359 --> 00:17:20,567 Wolves shadow them all along the way... and they're hungry. 120 00:17:51,400 --> 00:17:54,686 At first, the attack seems casual, random, 121 00:17:54,737 --> 00:17:59,233 but this running of the herd is a tactic to generate panic. 122 00:18:03,914 --> 00:18:07,283 ln the chaos, the young can be separated from their mothers. 123 00:18:18,473 --> 00:18:21,807 Now it's easier to target an individual calf. 124 00:18:32,781 --> 00:18:36,530 The calf may be young but it's capable of outrunning the wolf, 125 00:18:36,577 --> 00:18:38,653 if it manages to keep its footing. 126 00:18:52,720 --> 00:18:54,759 By this stage, the odds are even. 127 00:18:54,806 --> 00:18:57,178 Either the caribou will make a mistake, 128 00:18:57,225 --> 00:19:00,226 or after a mile or so, the wolf will give unp. 129 00:19:44,946 --> 00:19:49,941 April in the Arctic, and already the sun never sets. 130 00:19:55,333 --> 00:20:01,703 but further south, the sun works its magic in more gradual familiar ways. 131 00:20:13,437 --> 00:20:15,097 (Birdsong) 132 00:20:23,824 --> 00:20:25,282 (Birdsong) 133 00:21:05,163 --> 00:21:07,832 These are the forests that we know well. 134 00:21:07,874 --> 00:21:11,457 The broadleaf woodlands of Europe and North America. 135 00:21:11,503 --> 00:21:17,423 More than any other, these have been crowded out by towns and farmland. 136 00:21:17,468 --> 00:21:19,544 Only fragments remain. 137 00:21:19,596 --> 00:21:21,256 (Birdsong) 138 00:21:30,608 --> 00:21:34,855 Summers are longer here and deciduous trees can flourish. 139 00:21:34,905 --> 00:21:37,941 They're far more edible than conifers, 140 00:21:37,992 --> 00:21:41,693 so these forests bustle with life. 141 00:21:47,419 --> 00:21:51,666 Spring has also come early for the mandarin ducks. 142 00:21:53,760 --> 00:21:56,630 The female is leaving her nest high in the treetops. 143 00:21:56,680 --> 00:21:58,838 lt's her job to lead the way. 144 00:22:03,980 --> 00:22:07,515 lt's a long way down for a maiden flight. 145 00:22:07,567 --> 00:22:08,598 (Quacks) 146 00:22:10,612 --> 00:22:13,317 A few calls of encouragement are needed here. 147 00:23:01,921 --> 00:23:03,997 There are still two missing. 148 00:23:31,455 --> 00:23:36,247 Only two days old and already one great adventure behind them. 149 00:23:37,295 --> 00:23:41,756 What will the rest of the year hold for our planet's latest recruits? 150 00:24:09,582 --> 00:24:12,155 This is the legacy we've inherited, 151 00:24:12,210 --> 00:24:17,205 thanks to that all-important tilt of the Earth's axis - 152 00:24:17,257 --> 00:24:19,333 the rhythm of the seasons. 153 00:24:45,331 --> 00:24:49,792 The transformations of our world year on year, 154 00:25:03,310 --> 00:25:07,557 a seasonal cycle that seems increasingly unreliable. 155 00:25:18,368 --> 00:25:21,737 but there are parts of our world that have no seasons. 156 00:25:44,523 --> 00:25:48,437 May, in the tropics, but there is no spring. 157 00:25:49,487 --> 00:25:54,778 Here the sun shines for 1 2 hours a day every day of the year. 158 00:25:54,827 --> 00:25:58,113 This is what allows the jungle to grow unchecked 159 00:25:58,164 --> 00:26:00,833 and support so munch life. 160 00:26:06,924 --> 00:26:10,969 Rainforest now covers a third of the area it once did - 161 00:26:11,012 --> 00:26:14,096 a mere 3% of our planet's surface - 162 00:26:14,140 --> 00:26:20,060 and yet, it contains more than half of all the plants and animals on Earth. 163 00:26:20,106 --> 00:26:22,348 (Bird and animal calls) 164 00:27:14,584 --> 00:27:16,873 (Bird and animal calls) 165 00:27:22,260 --> 00:27:25,843 The rain forests of New Guinea are especially precious - 166 00:27:25,889 --> 00:27:30,385 home to 42 different kinds of birds of paradise, 167 00:27:30,436 --> 00:27:33,141 each more extraordinary than the last. 168 00:27:38,570 --> 00:27:41,239 (Cawing) 169 00:27:44,327 --> 00:27:46,201 (Squeaking echoes) 170 00:28:02,973 --> 00:28:05,345 (Cawing) 171 00:28:05,976 --> 00:28:08,218 (Cawing) 172 00:28:16,488 --> 00:28:19,405 This is a particularly rich forest, 173 00:28:19,450 --> 00:28:24,029 so the six-plumed bird of paradise has no problem finding food. 174 00:28:24,080 --> 00:28:27,366 He can concentrate on more important tasks, 175 00:28:27,418 --> 00:28:29,541 like tidying up his display area. 176 00:28:30,755 --> 00:28:32,913 He's obsessed with housework. 177 00:28:33,591 --> 00:28:36,046 Everything has to be spick and span. 178 00:28:47,649 --> 00:28:49,807 Finally, the stage is set. 179 00:29:12,803 --> 00:29:15,294 lt's a virtuoso performance. 180 00:29:15,347 --> 00:29:18,383 Unfortunately, no-one was watching. 181 00:29:18,434 --> 00:29:20,510 (Cawing) 182 00:29:21,938 --> 00:29:25,852 This contender is called the superb bird of paradise. 183 00:29:26,693 --> 00:29:29,729 This magician has a special trick. 184 00:29:29,780 --> 00:29:32,650 First, he advertises his show, 185 00:29:32,700 --> 00:29:34,989 calling to attract a female. 186 00:29:37,039 --> 00:29:38,866 With the audience in place, 187 00:29:38,916 --> 00:29:40,624 the show can begin. 188 00:29:56,019 --> 00:29:58,854 She just has to have been impressed with that. 189 00:29:58,897 --> 00:30:02,348 She retires a little way off to consider her verdict. 190 00:30:04,653 --> 00:30:07,689 After all that effort, can she still have doubts? 191 00:30:10,785 --> 00:30:15,827 You can't help feeling deflated when even your best wasn't good enough. 192 00:30:20,713 --> 00:30:27,001 3% of our planet, 50% of its plants and animals - 193 00:30:28,514 --> 00:30:30,886 nowhere is there more at stake. 194 00:30:34,688 --> 00:30:39,184 These tropical forests enjoy 1 2 hours of sunshine all year round, 195 00:30:39,235 --> 00:30:42,319 but they also need lots of rainfall. 196 00:30:47,577 --> 00:30:51,028 As weather patterns change, there are already signs 197 00:30:51,081 --> 00:30:53,453 that these forests are starting to dry. 198 00:31:35,716 --> 00:31:37,590 (Howling wind) 199 00:31:56,031 --> 00:31:59,898 Deserts cover one third of the land's surface on Planet Earth, 200 00:31:59,952 --> 00:32:03,072 and they're getting bigger every year. 201 00:32:39,080 --> 00:32:42,366 This is a land where only few can survive - 202 00:32:42,417 --> 00:32:45,204 only a special few - 203 00:32:46,255 --> 00:32:49,172 and the challenges are becoming greater than ever. 204 00:33:08,822 --> 00:33:12,440 June in the Kalahari Desert of Southern Africa. 205 00:33:18,041 --> 00:33:19,499 (Trumpeting) 206 00:33:20,127 --> 00:33:22,203 lt's the dry season here, 207 00:33:22,254 --> 00:33:26,916 and thousands of elephants have started the desperate trek for food and water. 208 00:33:47,241 --> 00:33:51,737 Using ancient route-ways handed down through the generations, 209 00:33:51,788 --> 00:33:56,949 all are making their way to the Okavango, 210 00:33:57,002 --> 00:34:00,122 a vast inland delta in the heart of the desert. 211 00:34:01,173 --> 00:34:05,835 At the moment it is dry, but water should come. 212 00:34:11,018 --> 00:34:13,853 Buffalo join the great trek. 213 00:34:13,896 --> 00:34:18,225 All across Southern Africa, millions of animals are on the move, 214 00:34:18,276 --> 00:34:22,404 on the same life or death quest for water. 215 00:34:51,147 --> 00:34:54,397 This tiny calf struggles to keep up. 216 00:34:55,152 --> 00:34:57,441 lts mother's instinct is to care for it, 217 00:34:57,488 --> 00:35:00,655 but her need for water is so desperate, 218 00:35:00,700 --> 00:35:03,535 she may be forced to leave it behind. 219 00:35:24,018 --> 00:35:27,719 Dust storms make the going tough all the way. 220 00:35:31,985 --> 00:35:33,265 (Trumpeting) 221 00:35:34,238 --> 00:35:37,441 They've become separated from the herd. 222 00:35:37,492 --> 00:35:40,244 This is a dangerous place to lose your way. 223 00:36:00,226 --> 00:36:04,306 There's sanctuary a few miles ahead - a small patch of woodland. 224 00:36:04,356 --> 00:36:07,143 They daren't rest until they reach it. 225 00:36:20,374 --> 00:36:22,995 The rest of the herd have escaped the storm, 226 00:36:23,044 --> 00:36:26,543 but they would all be at risk if they waited for the mother and the calf. 227 00:36:39,187 --> 00:36:42,473 Finally, the stragglers emerge from the dust. 228 00:36:51,451 --> 00:36:56,409 Blinded by sand, the calf barely has the strength to go on. 229 00:37:27,659 --> 00:37:29,651 The storm has died down. 230 00:37:31,830 --> 00:37:35,281 but not all the animals have been so lucky. 231 00:37:35,334 --> 00:37:37,789 One youngster got lost. 232 00:37:40,590 --> 00:37:47,969 Thirsty and exhausted, it follows the tracks of its mother, but in the wrong direction. 233 00:38:05,953 --> 00:38:10,532 Where dust meets water, the march of the deserts is halted. 234 00:38:15,881 --> 00:38:19,332 Sand dunes give way to prairies and savannah. 235 00:38:20,386 --> 00:38:24,336 Grass is a great unsung hero of our planet. 236 00:38:24,390 --> 00:38:30,594 lt keeps deserts in check and fuels many of Earth's great spectacles. 237 00:39:00,515 --> 00:39:06,435 The great game herds of East Africa all rely on this one miraculous plant. 238 00:39:40,936 --> 00:39:44,720 Every day on wide open plains the world over, 239 00:39:44,774 --> 00:39:48,143 a timeless ritual plays itself out - 240 00:39:48,194 --> 00:39:51,563 the drama of hunter and hunted. 241 00:40:32,036 --> 00:40:38,834 This is the circle of life that most of us, in our urban lives, have lost touch with. 242 00:42:36,261 --> 00:42:39,178 The elephants have been marching now for two weeks. 243 00:42:46,273 --> 00:42:50,057 The little calf and its mother have caught up with their herd, 244 00:42:50,110 --> 00:42:52,399 but they're desperately thirsty now. 245 00:43:03,209 --> 00:43:05,878 Perhaps spurred on by a memory from the past, 246 00:43:05,920 --> 00:43:09,870 the matriarch leads the herd to a temporary water hole - 247 00:43:09,925 --> 00:43:13,460 one that may have saved her life years ago. 248 00:44:04,237 --> 00:44:07,736 The elephants have to share the water with others. 249 00:44:07,782 --> 00:44:10,736 These are uneasy alliances. 250 00:44:20,213 --> 00:44:21,493 (Growls) 251 00:44:22,633 --> 00:44:23,664 (Trumpeting) 252 00:44:23,717 --> 00:44:24,748 (Growling) 253 00:44:29,057 --> 00:44:32,675 By day, the elephants dominate the water hole. 254 00:44:33,437 --> 00:44:34,895 (Thunder) 255 00:44:41,154 --> 00:44:44,986 ln the night time, the balance of power shifts. 256 00:44:48,829 --> 00:44:50,074 (Trumpeting) 257 00:44:53,418 --> 00:44:55,410 The calf and its mother are most at risk. 258 00:44:56,421 --> 00:44:59,173 They're closer to the lions than they can know. 259 00:45:05,932 --> 00:45:07,592 (Elephant growls) 260 00:45:08,769 --> 00:45:12,470 ln the darkness, an elephant's vision is little better than our own. 261 00:45:15,276 --> 00:45:17,981 Lions can see easily. 262 00:45:23,452 --> 00:45:25,076 (Elephant growls) 263 00:45:25,121 --> 00:45:26,698 (Lions growl) 264 00:45:28,917 --> 00:45:30,292 (Trumpets) 265 00:45:31,378 --> 00:45:33,667 The cats are ravenously hungry 266 00:45:33,714 --> 00:45:36,121 and the elephants sense the danger. 267 00:45:40,054 --> 00:45:41,216 (Elephant growls) 268 00:45:43,099 --> 00:45:44,344 (Trumpeting) 269 00:45:48,397 --> 00:45:49,428 (Elephant growls) 270 00:45:49,482 --> 00:45:51,558 The lions bide their time. 271 00:46:00,911 --> 00:46:03,449 lt's the calves they're after. 272 00:46:14,385 --> 00:46:15,843 (Elephant growls) 273 00:46:29,027 --> 00:46:30,651 (Squealing and growling) 274 00:46:36,619 --> 00:46:38,077 (Lions growling) 275 00:46:38,121 --> 00:46:41,988 As the lions rally, the elephants herd their young together, 276 00:46:42,042 --> 00:46:45,956 forming a protective circle to keep them away from the predators. 277 00:46:59,520 --> 00:47:04,016 The cats have to find an opening in this defensive wall of hide. 278 00:47:09,156 --> 00:47:10,864 (Elephants growl) 279 00:47:19,960 --> 00:47:21,288 (Lion growls) 280 00:47:22,797 --> 00:47:24,042 (Trumpeting) 281 00:47:34,351 --> 00:47:37,020 (Growls) 282 00:47:43,320 --> 00:47:45,727 (Growling) 283 00:47:49,035 --> 00:47:50,909 (All lions growling) 284 00:48:01,090 --> 00:48:03,248 The calves are too well protected. 285 00:48:03,301 --> 00:48:07,714 The lions will have to take a risk, change their tactics. 286 00:48:10,267 --> 00:48:14,763 Normally, a solitary lion would stand no chance against this elephant, 287 00:48:14,814 --> 00:48:18,397 but the whole pride is here - 30 of them - 288 00:48:18,443 --> 00:48:21,112 and they're specialist elephant hunters. 289 00:48:23,282 --> 00:48:25,440 (Elephant growls) 290 00:48:31,792 --> 00:48:33,452 (Elephant growls) 291 00:48:46,559 --> 00:48:48,219 (Elephant squeals) 292 00:48:54,109 --> 00:48:55,567 (Thunderclap ) 293 00:49:08,959 --> 00:49:14,001 For the survivors, the Okavango Delta is still many miles away. 294 00:49:27,731 --> 00:49:33,983 As the deserts grow, and traditional migration routes are blocked by farms and fences, 295 00:49:34,030 --> 00:49:37,233 elephants must trek ever greater distances. 296 00:49:48,880 --> 00:49:53,756 The sun that scorches the desert also brings water to the land. 297 00:49:54,720 --> 00:49:57,425 As it beats down on tropical seas, 298 00:49:57,473 --> 00:50:02,978 moisture rises from the warming oceans powering our global weather system. 299 00:50:51,869 --> 00:50:56,946 Moist winds from the Indian oceans sweep north towards the Himalayas. 300 00:50:59,544 --> 00:51:04,787 As the air rises, so it cools and the water falls as snow. 301 00:51:19,692 --> 00:51:23,904 The scene is set for one of nature�s most challenging migrations. 302 00:51:27,576 --> 00:51:34,078 Each year, thousands of demoiselle cranes try to escape the harsh winters in Mongolia, 303 00:51:34,125 --> 00:51:38,075 by flying south to the warmer climes of lndia. 304 00:51:45,388 --> 00:51:50,264 To get there, they have to cross the highest mountain range on Earth, 305 00:51:51,311 --> 00:51:52,971 the Himalayas. 306 00:52:06,245 --> 00:52:11,536 As the sun heats these great slopes, warm air rises from the valleys, 307 00:52:11,585 --> 00:52:15,535 turning, by late morning, to ferocious winds. 308 00:52:29,647 --> 00:52:32,352 The cranes hit violent turbulence. 309 00:52:36,154 --> 00:52:40,366 They'll have to turn back or risk certain death. 310 00:53:13,906 --> 00:53:19,067 The sun's rays weaken in the afternoon and the turbulence falls away, 311 00:53:19,120 --> 00:53:21,243 but it's too late for today. 312 00:53:54,368 --> 00:53:57,037 A new day, a new chance. 313 00:53:58,081 --> 00:54:01,746 The adults must guide their young on this hazardous trip. 314 00:54:09,052 --> 00:54:13,714 lt's early morning and the warm air is already rising fast. 315 00:54:13,766 --> 00:54:17,182 They use the thermals to gain height. 316 00:54:27,323 --> 00:54:31,368 Soon it'll get stormy again, maybe too stormy to go on. 317 00:54:51,100 --> 00:54:57,898 ln the final ascent, every wing beat is a desperate battle against the freezing winds. 318 00:55:26,974 --> 00:55:32,182 At last, they've made it. They've conquered the highest peaks on Earth. 319 00:55:33,732 --> 00:55:38,061 On the other side there's sanctuary for the winter. 320 00:55:58,468 --> 00:56:03,011 The sun melts the snow and the waters go on their way again - 321 00:56:04,058 --> 00:56:07,392 the start of their long journey back to the oceans. 322 00:57:09,967 --> 00:57:12,505 This is the great unending cycle. 323 00:57:12,553 --> 00:57:18,224 sunlight and fresh water bringing life to every corner of Planet Earth. 324 00:57:47,718 --> 00:57:51,467 For generations, humans and animals alike 325 00:57:51,514 --> 00:57:56,472 come to depend on the great rivers and their seemingly endless flow. 326 00:59:11,564 --> 00:59:16,310 After months of drought, the rivers begin to flow again in the Kalahari. 327 00:59:16,361 --> 00:59:19,979 The buffalo reach the end of their long journey. 328 00:59:27,248 --> 00:59:29,953 As the water sweeps through desert lands, 329 00:59:30,002 --> 00:59:34,629 the Okavango is transformed into a fertile paradise. 330 00:59:57,616 --> 01:00:00,486 This is an Africa we rarely see - 331 01:00:00,536 --> 01:00:05,957 a lush water world totally reliant on a seasonal flood, 332 01:00:06,001 --> 01:00:10,959 originating from a tropical ocean thousands of miles away. 333 01:00:31,488 --> 01:00:34,061 Many animals are quite at home in the flood, 334 01:00:34,116 --> 01:00:37,900 but there are some more apprehensive bathers. 335 01:00:42,793 --> 01:00:44,038 (Grumbling) 336 01:00:49,884 --> 01:00:51,426 (Squeaking) 337 01:00:59,562 --> 01:01:00,593 (Grunts) 338 01:01:05,319 --> 01:01:06,350 (Grunts) 339 01:01:13,370 --> 01:01:14,401 (Squeaks) 340 01:01:17,458 --> 01:01:18,489 (Squeaks) 341 01:01:52,372 --> 01:01:56,868 After weeks of marching, the elephants are exhausted. 342 01:01:57,920 --> 01:02:00,874 They struggle to stay focussed on the road ahead. 343 01:02:10,810 --> 01:02:12,518 (Soft growls) 344 01:02:12,562 --> 01:02:14,020 (Calf squeaks) 345 01:02:18,903 --> 01:02:21,394 The matriarch can smell the water, 346 01:02:21,447 --> 01:02:25,196 and encourages the herd to make one last effort. 347 01:02:27,204 --> 01:02:28,449 (Calf squeals) 348 01:02:57,572 --> 01:02:59,695 After so many weeks, 349 01:02:59,741 --> 01:03:02,991 many hundreds of miles, 350 01:03:03,036 --> 01:03:04,910 they've arrived. 351 01:03:05,956 --> 01:03:07,414 (Trumpeting) 352 01:03:08,417 --> 01:03:10,291 (Trumpeting) 353 01:03:34,447 --> 01:03:35,905 (Trumpeting) 354 01:03:53,302 --> 01:03:54,760 (Trumpeting) 355 01:04:07,109 --> 01:04:08,140 (Soft growls) 356 01:04:12,741 --> 01:04:18,328 Like the elephants, these waters have travelled great distances to reach here. 357 01:04:19,540 --> 01:04:25,329 And all along the way, their flow is threatened by extraction for towns and farmland. 358 01:04:26,381 --> 01:04:30,924 ln its long life, the calf will make this journey many times. 359 01:04:32,513 --> 01:04:37,222 Whether the flood will always arrive is far from certain. 360 01:04:56,249 --> 01:05:00,496 The seasonal cycle that drives the lives of elephants on land, 361 01:05:00,545 --> 01:05:04,044 is just as important in the oceans. 362 01:05:27,535 --> 01:05:29,611 (Whale song) 363 01:05:52,813 --> 01:05:58,484 lt's July and the humpback whales are in their breeding grounds in the tropics. 364 01:06:18,927 --> 01:06:21,844 This calf is no more than a few weeks old 365 01:06:21,888 --> 01:06:24,046 and as he begins to tire, 366 01:06:24,099 --> 01:06:28,678 his mother supports him close to the surface, so that he can breathe. 367 01:06:49,003 --> 01:06:52,704 These shallow equatorial waters make good nurseries - 368 01:06:52,757 --> 01:06:56,707 they're warm and calm and there are few predators. 369 01:07:11,862 --> 01:07:17,283 The playful calf is now drinking 600 litres of milk a day, 370 01:07:17,327 --> 01:07:19,403 but its mother is starving. 371 01:07:19,454 --> 01:07:23,321 There's nothing for her to eat in these crystal clear waters. 372 01:07:44,983 --> 01:07:51,152 To find food, she will have to lead her calf on an epic 4,000-mile journey 373 01:07:51,199 --> 01:07:56,157 to richer feeding grounds at the southern extremes of our planet. 374 01:08:00,876 --> 01:08:04,577 This is the longest migration by any marine mammal, 375 01:08:04,631 --> 01:08:09,589 and it depends entirely on a healthy ocean all along the way. 376 01:08:39,963 --> 01:08:44,459 out in the open ocean, the whales meet others searching for food. 377 01:08:55,897 --> 01:08:58,470 Dolphins are closing in on their prey. 378 01:09:07,411 --> 01:09:10,116 A hundred sailfish join in the attack. 379 01:09:14,085 --> 01:09:18,712 Reaching almost 70 miles an hour, they are the cheetahs of the sea. 380 01:10:04,809 --> 01:10:09,518 Mother and calf swim on south through the vast open oceans. 381 01:10:09,565 --> 01:10:11,557 They have to cross half the globe, 382 01:10:11,609 --> 01:10:15,856 from the equator all the way to the edge of Antarctica. 383 01:10:25,082 --> 01:10:27,999 The tropical seas are a long way behind them now. 384 01:10:28,044 --> 01:10:31,045 They're heading for stormy seasonal waters. 385 01:10:32,299 --> 01:10:37,091 Strong winds and currents draw nutrients up from the depths 386 01:10:37,138 --> 01:10:41,350 and life blooms wherever the sun's rays can penetrate. 387 01:11:30,365 --> 01:11:34,232 The mother knows there are even richer feeding grounds further south, 388 01:11:34,286 --> 01:11:38,331 and hurries her calf through these dangerous waters. 389 01:11:55,102 --> 01:11:57,178 The great white shark. 390 01:12:09,994 --> 01:12:12,449 Great whites attack whale calves, 391 01:12:13,498 --> 01:12:15,823 but they're not the victims today. 392 01:13:25,163 --> 01:13:29,872 These magnificent predators, at the very top of the food chain, 393 01:13:29,918 --> 01:13:33,121 are a vital part of a healthy ocean... 394 01:13:34,173 --> 01:13:38,634 and yet we slaughter almost a hundred million of them every year. 395 01:13:40,264 --> 01:13:42,969 Their populations are in freefall. 396 01:14:13,301 --> 01:14:14,961 (Creaking) 397 01:14:25,440 --> 01:14:30,268 August in the Arctic and the ice is vanishing fast. 398 01:14:31,364 --> 01:14:34,531 The two cubs cannot cope with the shifting platform 399 01:14:34,576 --> 01:14:38,241 and their hungry mother is forced to lead them back to shore. 400 01:14:43,628 --> 01:14:45,086 (Soft growls) 401 01:14:51,595 --> 01:14:57,100 out to sea, the ice is now too thin to support the cubs' father. 402 01:15:18,626 --> 01:15:24,250 Glacial melt waters pour from the land, mix with the sea, and speed up the thaw. 403 01:15:35,687 --> 01:15:40,729 Each year, as the climate warms, there is less and less ice in the Arctic. 404 01:15:41,777 --> 01:15:44,778 This is a disaster for polar bears. 405 01:15:44,822 --> 01:15:50,161 Without a solid platform, they struggle to hunt the seals they need to survive. 406 01:16:01,758 --> 01:16:02,920 (Growls) 407 01:16:07,932 --> 01:16:08,963 (Growls) 408 01:16:26,537 --> 01:16:31,283 How will the father make it through the year now that the ice is almost gone? 409 01:16:38,467 --> 01:16:42,595 September and the whales are 3,000 miles from the equator. 410 01:16:42,638 --> 01:16:46,173 The waters are getting colder and rougher. 411 01:16:47,227 --> 01:16:49,552 Mother and calf must stay close. 412 01:16:58,907 --> 01:17:03,450 So as not to lose track of each other, they slap their fins on the surface. 413 01:17:03,496 --> 01:17:07,708 They can hear these sound signals above the roar of the ocean. 414 01:17:46,920 --> 01:17:49,672 The far south...at last. 415 01:18:08,737 --> 01:18:13,150 October, and the whales are entering polar waters. 416 01:18:13,200 --> 01:18:18,657 Summer is drawing to a close in the north, but here it is only just beginning. 417 01:18:31,012 --> 01:18:35,306 As the sun melts the ice, life returns. 418 01:18:48,782 --> 01:18:54,488 The whales have finally reached Antarctica in time for the summer. 419 01:18:59,253 --> 01:19:01,127 Adelie penguins... 420 01:19:02,047 --> 01:19:05,381 and they're in a hurry to reach their nesting grounds. 421 01:19:34,376 --> 01:19:37,330 December and the sun does not set. 422 01:19:42,635 --> 01:19:45,636 The Antarctic summer is all too short, 423 01:19:45,681 --> 01:19:51,221 but for a few brief months its warmth unlocks sheltered bays. 424 01:20:07,205 --> 01:20:10,206 ln the depths, something stirs. 425 01:20:38,533 --> 01:20:44,903 At last, after their 4,000-mile journey, the humpback whales can feed. 426 01:20:54,134 --> 01:21:00,671 They harvest krill, shrimps that begin to swarm here as soon as the ice retreats. 427 01:21:15,783 --> 01:21:19,199 Now, at last, the mother can replenish her reserves 428 01:21:19,246 --> 01:21:23,113 as she and her calf join the rest of the team. 429 01:21:29,174 --> 01:21:32,792 The whales create a spiralling net of bubbles, 430 01:21:32,845 --> 01:21:36,677 concentrating the krill into one gigantic feast. 431 01:21:48,321 --> 01:21:51,607 They work round the clock, for the boom will be short-lived. 432 01:21:51,658 --> 01:21:57,412 Summer is fading fast and they'll soon have to return to tropical waters. 433 01:22:03,296 --> 01:22:09,382 These whales, and most of the life in Antarctica, ultimately depend on krill. 434 01:22:10,429 --> 01:22:14,641 Without it, the far south would be almost deserted. 435 01:22:15,977 --> 01:22:21,019 but krill depend on ice and ice is in decline. 436 01:22:31,912 --> 01:22:34,201 Winter in Antarctica 437 01:22:34,248 --> 01:22:37,747 and the greatest seasonal change on our planet is underway. 438 01:22:57,441 --> 01:22:59,848 The sun begins to retreat. 439 01:23:01,821 --> 01:23:05,901 Soon the continent will be plunged back into darkness. 440 01:23:15,003 --> 01:23:20,424 The Aurora Australia illuminates the southern skies, 441 01:23:20,467 --> 01:23:26,422 but these spectacular lights bring no warmth to the wilderness of ice. 442 01:24:04,226 --> 01:24:07,927 Back in the north of the planet, where our story began, 443 01:24:07,980 --> 01:24:11,563 the sea ice has completely disappeared. 444 01:24:28,420 --> 01:24:31,089 our male polar bear is in great danger now. 445 01:24:32,883 --> 01:24:37,629 lf he doesn't find land soon in this vast ocean, he will drown. 446 01:25:03,961 --> 01:25:06,037 (Grunts and growls) 447 01:25:27,279 --> 01:25:29,236 After many days at sea, 448 01:25:29,281 --> 01:25:34,489 the exhausted bear is drawn by the pungent smells of the colony. 449 01:25:45,341 --> 01:25:48,046 He has lost half his body weight. 450 01:25:48,094 --> 01:25:50,466 He's desperate for food, 451 01:25:50,514 --> 01:25:54,013 but walrus are munch larger than his unseal prey. 452 01:26:00,024 --> 01:26:02,100 lt's the pups he'll have to get to. 453 01:26:02,152 --> 01:26:06,898 The powerful adults can do terrible damage with their huge tusks. 454 01:26:11,287 --> 01:26:13,363 (Grunting and growling) 455 01:26:47,120 --> 01:26:49,326 The walrus sense the danger. 456 01:26:50,457 --> 01:26:52,864 The adults close ranks around their young. 457 01:26:56,047 --> 01:26:57,790 He tests the barrier. 458 01:27:01,553 --> 01:27:02,963 lt stands firm. 459 01:27:06,517 --> 01:27:09,090 He may be the world's biggest land carnivore, 460 01:27:09,145 --> 01:27:14,222 but it looks like he's met his match and he's badly weakened by starvation. 461 01:27:22,994 --> 01:27:25,366 A pup hides behind its mother. 462 01:27:28,667 --> 01:27:30,992 lf he can just prize her off. 463 01:27:54,906 --> 01:27:57,361 With the herd retreating to the safety of the water, 464 01:27:57,408 --> 01:27:59,400 the bear has little time left. 465 01:28:02,498 --> 01:28:03,778 He tries again. 466 01:28:03,832 --> 01:28:05,077 (Growling) 467 01:28:06,460 --> 01:28:08,334 (Walrus growls) 468 01:28:16,222 --> 01:28:19,057 And again, in sheer frustration now. 469 01:28:50,302 --> 01:28:53,967 He has to avoid the lethal tusks at all costs. 470 01:28:54,015 --> 01:28:55,473 (Walrus growls) 471 01:28:57,060 --> 01:28:58,518 (Howls) 472 01:29:21,046 --> 01:29:23,371 lt slips from his grasp. 473 01:29:40,276 --> 01:29:43,360 lt's only when bears are on the verge of starvation 474 01:29:43,404 --> 01:29:46,773 that they'll risk attacking such dangerous prey. 475 01:29:58,088 --> 01:29:59,119 (Grunts) 476 01:29:59,172 --> 01:30:01,627 This one took the gamble...and lost. 477 01:30:20,196 --> 01:30:22,272 The walrus are calm again. 478 01:30:23,534 --> 01:30:25,610 The bear is no longer a threat. 479 01:30:29,374 --> 01:30:33,372 Unable to feed, he can't survive. 480 01:30:49,146 --> 01:30:52,147 As the global climate continues to warm, 481 01:30:52,191 --> 01:30:55,690 and the arctic ice melts sooner every year, 482 01:30:55,737 --> 01:30:59,272 more of his kind will come to this sad end. 483 01:31:23,519 --> 01:31:28,015 A year has passed and the two bear cubs have beaten the odds. 484 01:31:34,990 --> 01:31:38,240 They've left their mother...and are thriving. 485 01:32:09,446 --> 01:32:13,823 Their ever-shifting world is changing faster by the day, 486 01:32:13,868 --> 01:32:17,652 but for now, they're keeping one step ahead. 487 01:32:18,874 --> 01:32:24,331 Their father's adventurous spirit lives on in these magnificent youngsters - 488 01:32:25,464 --> 01:32:30,173 the next generation and proof of the resilience of life. 489 01:33:01,130 --> 01:33:05,792 The polar bear has become an emblem for the state of our planet 490 01:33:05,844 --> 01:33:09,676 and for all the creatures who are struggling to live alongside uns. 491 01:33:43,470 --> 01:33:46,139 Finally, we've begun to understand 492 01:33:46,182 --> 01:33:51,556 how precarious is the state of our once lucky planet. 493 01:33:53,356 --> 01:33:58,351 lf we are to go on sharing Earth with such a rich variety of life, 494 01:33:58,404 --> 01:34:02,733 and preserve its fragile balance for our own children, 495 01:34:02,784 --> 01:34:04,860 now, more than ever... 496 01:34:06,038 --> 01:34:08,114 it is in our hands.