1 00:00:35,400 --> 00:00:39,860 There is only one planet in the universe, as far as we know, 2 00:00:39,860 --> 00:00:42,100 where there is life. 3 00:00:42,100 --> 00:00:43,500 The Earth. 4 00:00:43,500 --> 00:00:44,940 Our home. 5 00:00:46,780 --> 00:00:48,620 The perfect planet. 6 00:00:52,700 --> 00:00:54,940 Life here is only possible 7 00:00:54,940 --> 00:00:59,260 because of a unique balance of natural forces. 8 00:01:03,660 --> 00:01:08,100 Energy from the sun powers the living world. 9 00:01:08,100 --> 00:01:10,940 GRUNTING 10 00:01:10,940 --> 00:01:14,420 THUNDER CRASHES 11 00:01:14,420 --> 00:01:18,540 Weather systems transport fresh water around the globe. 12 00:01:23,940 --> 00:01:26,420 And powerful ocean currents 13 00:01:26,420 --> 00:01:29,620 circulate life's essential nutrients. 14 00:01:33,940 --> 00:01:38,820 This series will reveal how these global forces have worked together 15 00:01:38,820 --> 00:01:42,820 to create our planet's fragile life-support system. 16 00:01:46,900 --> 00:01:50,580 One of these forces is so important 17 00:01:50,580 --> 00:01:54,780 that life would never have even started without it. 18 00:02:16,820 --> 00:02:19,580 Across the surface of our planet, 19 00:02:19,580 --> 00:02:23,620 there are over 1,500 active volcanoes. 20 00:02:35,140 --> 00:02:39,180 This is the most active - Kilauea in Hawaii. 21 00:02:54,780 --> 00:02:59,260 Here, magma - liquid rock from the planet's hot interior - 22 00:02:59,260 --> 00:03:03,060 bursts out through fractures in the Earth's crust, 23 00:03:03,060 --> 00:03:06,700 and it's been flowing for months. 24 00:03:17,300 --> 00:03:20,580 Nothing can stand in the lava's way. 25 00:03:31,700 --> 00:03:35,220 Volcanoes are certainly destructive. 26 00:03:35,220 --> 00:03:39,260 But without these powerful underground forces, 27 00:03:39,260 --> 00:03:41,860 there would be no breathable atmosphere. 28 00:03:44,020 --> 00:03:45,900 No oceans. 29 00:03:51,140 --> 00:03:52,820 No land. 30 00:03:54,420 --> 00:03:56,020 No life. 31 00:03:58,940 --> 00:04:02,100 We can't control volcanoes, 32 00:04:02,100 --> 00:04:05,860 but they're vital for all living things on Planet Earth. 33 00:04:05,860 --> 00:04:09,260 RUMBLING 34 00:04:14,220 --> 00:04:18,420 This is Ol Doinyo Lengai in Tanzania. 35 00:04:21,300 --> 00:04:23,940 It's one of Africa's most active volcanoes, 36 00:04:23,940 --> 00:04:28,580 and has erupted over 15 times in the last 100 years. 37 00:04:33,500 --> 00:04:37,140 On its northern flank lies Lake Natron, 38 00:04:37,140 --> 00:04:39,660 400 square miles in extent, 39 00:04:39,660 --> 00:04:44,020 and one of the world's most corrosive bodies of water. 40 00:04:48,660 --> 00:04:50,780 The water wells up from deep below, 41 00:04:50,780 --> 00:04:55,420 carrying such a concentration of chemicals that it can burn skin. 42 00:05:08,460 --> 00:05:11,220 But one animal thrives here. 43 00:05:16,300 --> 00:05:18,740 Volcano birds. 44 00:05:20,380 --> 00:05:25,220 Nearly two million lesser flamingos live in East Africa 45 00:05:25,220 --> 00:05:27,900 and all of them come here to breed. 46 00:05:30,740 --> 00:05:34,100 FLAMINGOS CALL 47 00:05:34,100 --> 00:05:37,700 But they can only nest here when the lake's level 48 00:05:37,700 --> 00:05:41,620 drops so far that in the centre, its bed is exposed. 49 00:05:43,740 --> 00:05:46,220 And that rare moment is now. 50 00:05:55,260 --> 00:05:59,020 How they know when the conditions are right is a mystery, 51 00:05:59,020 --> 00:06:03,220 but some have flown thousands of miles to be here. 52 00:06:05,740 --> 00:06:08,700 The flamingos head for the middle of the lake, 53 00:06:08,700 --> 00:06:13,300 where the intense evaporation has created islands of salt. 54 00:06:16,500 --> 00:06:19,540 It's here that the birds build their nests, 55 00:06:19,540 --> 00:06:22,180 over three miles from the lake's edge 56 00:06:22,180 --> 00:06:26,300 and safe from land predators, which are unable to cross 57 00:06:26,300 --> 00:06:29,020 the surrounding moat of caustic soda. 58 00:06:35,500 --> 00:06:38,580 FLAMINGO CALLS 59 00:06:40,060 --> 00:06:43,500 The single egg is laid on a mount of hardened salt 60 00:06:43,500 --> 00:06:45,820 built by the adults, 61 00:06:45,820 --> 00:06:49,980 its height an insurance against a sudden rise in water level... 62 00:06:51,300 --> 00:06:54,220 ...which often happens on Lake Natron. 63 00:06:58,700 --> 00:07:01,580 As the centre dries and enlarges, 64 00:07:01,580 --> 00:07:05,140 more and more flamingos arrive to nest on it. 65 00:07:07,620 --> 00:07:10,260 In good years, such as now, 66 00:07:10,260 --> 00:07:13,100 as many as half a million pairs breed here. 67 00:07:23,740 --> 00:07:26,580 After 28 days of incubation, 68 00:07:26,580 --> 00:07:30,180 a chick emerges into Natron's harsh glare. 69 00:07:33,420 --> 00:07:38,020 Here, temperatures can rise to 55 degrees Celsius. 70 00:07:44,220 --> 00:07:48,020 Mother's wing, however, can serve as a sun shield. 71 00:07:51,300 --> 00:07:52,620 CHICK CHIRPS 72 00:07:52,620 --> 00:07:55,740 The chick is fed a rich liquid 73 00:07:55,740 --> 00:07:58,620 made of the lake's barely digested algae 74 00:07:58,620 --> 00:08:01,060 and traces of its parent's blood. 75 00:08:09,020 --> 00:08:13,260 After a few days, the chick is strong enough to stretch its legs. 76 00:08:13,260 --> 00:08:16,300 CHIRPS 77 00:08:17,700 --> 00:08:21,020 CHIRPING 78 00:08:21,020 --> 00:08:25,860 It then joins a growing creche, made up of chicks of different ages. 79 00:08:29,980 --> 00:08:34,420 Soon, the need for fresh water will force the infant birds 80 00:08:34,420 --> 00:08:37,180 to trek to springs on the lake's edge. 81 00:08:39,060 --> 00:08:41,100 A journey they have to make on foot, 82 00:08:41,100 --> 00:08:44,660 as their flight feathers have yet to develop. 83 00:08:50,340 --> 00:08:54,900 Every day, the adults fly to these springs to feed. 84 00:08:58,780 --> 00:09:02,820 Here, on the lake's margins, they collect algae that flourish 85 00:09:02,820 --> 00:09:04,900 in the volcanic water - 86 00:09:04,900 --> 00:09:07,740 vital food for the flamingos. 87 00:09:15,220 --> 00:09:18,460 It's the algae that turn the flamingos' feathers pink. 88 00:09:20,700 --> 00:09:22,980 It even colours their eyes. 89 00:09:27,620 --> 00:09:31,020 The adults spend most of their day at the springs, 90 00:09:31,020 --> 00:09:34,340 and now their chicks are going to join them there. 91 00:09:46,060 --> 00:09:47,260 CHIRPS 92 00:09:48,300 --> 00:09:50,980 No-one wants to get left behind. 93 00:09:56,860 --> 00:10:01,140 It's a three-mile march over razor-sharp flakes of soda 94 00:10:01,140 --> 00:10:03,340 and sticky, caustic mud. 95 00:10:06,900 --> 00:10:10,660 A life-threatening trial, especially for the youngest chicks. 96 00:10:16,380 --> 00:10:19,820 The groups merge into one giant creche. 97 00:10:51,260 --> 00:10:53,140 CHIRPS 98 00:10:53,140 --> 00:10:56,980 For some, the challenges are just too great. 99 00:11:00,420 --> 00:11:03,860 Exhaustion overcomes the weakest. 100 00:11:14,660 --> 00:11:17,420 And now, there is yet another threat. 101 00:11:22,580 --> 00:11:24,380 Marabou storks. 102 00:11:26,420 --> 00:11:28,940 They have long legs like a flamingo, 103 00:11:28,940 --> 00:11:31,700 but a beak like a Roman sword. 104 00:11:36,380 --> 00:11:38,420 And they are patient, 105 00:11:38,420 --> 00:11:40,740 waiting for an easy target. 106 00:11:53,900 --> 00:11:57,100 Their very presence creates panic among the chicks. 107 00:12:03,100 --> 00:12:06,500 The smallest avoid being trampled underfoot 108 00:12:06,500 --> 00:12:08,780 by travelling on the outside of the group. 109 00:12:11,540 --> 00:12:14,580 But that exposes them to attack. 110 00:12:18,820 --> 00:12:21,380 Their only defence is to run. 111 00:12:25,940 --> 00:12:27,900 But you have little chance 112 00:12:27,900 --> 00:12:30,700 when you're barely ankle-high to your pursuer. 113 00:12:41,180 --> 00:12:43,540 FLAMINGOS SHRIEK 114 00:13:03,380 --> 00:13:06,340 Stragglers will almost certainly be taken. 115 00:13:09,460 --> 00:13:13,940 But there comes a point when every stork has had its fill. 116 00:13:27,900 --> 00:13:32,220 This little chick is very lucky. 117 00:13:39,700 --> 00:13:43,460 At last, the youngsters reach the freshwater springs 118 00:13:43,460 --> 00:13:47,020 at the lake's margin to rejoin their parents. 119 00:13:48,860 --> 00:13:53,500 Almost unbelievably, each chick has a unique call 120 00:13:53,500 --> 00:13:56,260 that its parent can recognise. 121 00:13:56,260 --> 00:13:58,860 CHICK CHIRPS 122 00:14:04,660 --> 00:14:07,300 CHIRPING 123 00:14:24,580 --> 00:14:28,380 Ultimately, so do all living things. 124 00:14:35,340 --> 00:14:38,260 Over 80% of the Earth's surface 125 00:14:38,260 --> 00:14:42,660 is the result of magma bursting up from the molten interior. 126 00:14:44,340 --> 00:14:46,140 BOOM 127 00:14:50,820 --> 00:14:54,380 The process started four billion years ago 128 00:14:54,380 --> 00:14:56,700 and it still continues today. 129 00:15:02,180 --> 00:15:06,660 When lava cools, it solidifies into rock, 130 00:15:06,660 --> 00:15:11,500 and eventually weathers into land that can support life. 131 00:15:19,300 --> 00:15:24,540 All the Galapagos Islands in the Pacific are volcanic, 132 00:15:24,540 --> 00:15:27,740 and Fernandina is the youngest of them. 133 00:15:29,380 --> 00:15:31,180 And still growing. 134 00:15:39,540 --> 00:15:44,540 At its centre, a volcanic crater four miles wide... 135 00:15:46,580 --> 00:15:49,260 ...and over 800 metres deep. 136 00:15:55,180 --> 00:15:59,620 It seems dormant, but it was erupting only two weeks ago. 137 00:16:06,380 --> 00:16:11,620 Even so, there are some who depend on the heat from this volcano. 138 00:16:17,540 --> 00:16:22,580 A female land iguana, heavy with eggs, approaches the crater's rim. 139 00:16:25,460 --> 00:16:28,860 It took her ten days to climb up here, 140 00:16:28,860 --> 00:16:32,340 but the toughest part of her journey is still ahead. 141 00:16:33,780 --> 00:16:37,220 She's going to descend into the crater itself. 142 00:16:50,020 --> 00:16:53,660 Frequent tremors make the crater walls unstable. 143 00:17:02,820 --> 00:17:05,460 More people have travelled in space 144 00:17:05,460 --> 00:17:08,780 than have visited the bottom of Fernandina's crater. 145 00:17:12,540 --> 00:17:14,780 But instinct drives her on. 146 00:17:17,660 --> 00:17:19,900 The warm volcanic ash on the crater floor 147 00:17:19,900 --> 00:17:23,980 has the perfect temperature for incubating her eggs. 148 00:17:26,580 --> 00:17:28,980 But there are no clear paths down. 149 00:17:32,140 --> 00:17:35,580 Any made last year have been destroyed by rock falls. 150 00:17:56,140 --> 00:17:59,060 The slope is steep and unstable. 151 00:18:01,540 --> 00:18:04,820 Tumbling rocks quickly become an avalanche. 152 00:18:17,900 --> 00:18:20,540 With the boulders falling down away from her, 153 00:18:20,540 --> 00:18:22,940 she's not in immediate danger. 154 00:18:26,540 --> 00:18:29,740 But behind her, higher up, 155 00:18:29,740 --> 00:18:33,140 two other females have also started the descent. 156 00:18:33,140 --> 00:18:35,780 ROCKS RATTLE 157 00:18:39,780 --> 00:18:42,940 And now she is in the firing line. 158 00:18:48,220 --> 00:18:50,020 THUD 159 00:19:06,900 --> 00:19:08,540 She's safe. 160 00:19:12,820 --> 00:19:14,260 FLIES BUZZ 161 00:19:14,260 --> 00:19:16,860 Others before her haven't been so lucky. 162 00:19:20,580 --> 00:19:22,140 But she's undeterred. 163 00:19:48,620 --> 00:19:53,020 At last, after an eight-hour descent, 164 00:19:53,020 --> 00:19:55,460 she reaches the crater floor. 165 00:19:59,580 --> 00:20:03,460 Now she must find a suitable place to dig her nest. 166 00:20:11,300 --> 00:20:13,980 The best sites are already taken. 167 00:20:18,820 --> 00:20:22,260 And nesting females are very aggressive. 168 00:20:29,140 --> 00:20:31,820 A nodding head means keep away. 169 00:20:34,380 --> 00:20:35,740 Push off! 170 00:20:40,980 --> 00:20:43,660 Ignored warnings are met with force. 171 00:21:04,340 --> 00:21:08,060 But she's come a long way, and she's not going to give up now. 172 00:21:16,420 --> 00:21:20,660 She, too, starts to dig a hole in which to lay her eggs. 173 00:21:25,660 --> 00:21:28,860 That done, she will head back, 174 00:21:28,860 --> 00:21:32,380 leaving the volcano to provide the warmth her eggs need 175 00:21:32,380 --> 00:21:33,980 if they are to hatch. 176 00:21:37,380 --> 00:21:40,900 Sometimes, of course, the volcano erupts 177 00:21:40,900 --> 00:21:44,940 and destroys not only eggs but many nesting adults. 178 00:21:51,500 --> 00:21:53,820 But for the iguanas, 179 00:21:53,820 --> 00:21:57,140 the benefits of nesting in the crater are so great 180 00:21:57,140 --> 00:21:59,180 that it's worth all the risks. 181 00:22:04,180 --> 00:22:09,780 Volcanic islands make up just 5% of the planet's land, 182 00:22:09,780 --> 00:22:13,380 but they're home to nearly 20% of its species. 183 00:22:17,260 --> 00:22:21,540 Animals often evolve very swiftly on islands, 184 00:22:21,540 --> 00:22:24,660 cut off from their mainland relatives 185 00:22:24,660 --> 00:22:27,460 and faced with the challenges of isolation. 186 00:22:32,220 --> 00:22:35,980 This is Wolf, an extinct volcano 187 00:22:35,980 --> 00:22:40,460 and one of the most remote islands of the Galapagos, 188 00:22:40,460 --> 00:22:43,460 800 miles from the nearest large landmass 189 00:22:43,460 --> 00:22:45,780 and over a million years old. 190 00:22:49,060 --> 00:22:50,220 A finch. 191 00:22:51,580 --> 00:22:53,980 A female. 192 00:22:53,980 --> 00:22:58,700 Its ancestors doubtless were blown here by storms many centuries ago. 193 00:23:00,540 --> 00:23:04,780 Like most finches, they feed on seeds, nectar and insects. 194 00:23:07,260 --> 00:23:10,420 But there's little food of any kind on Wolf. 195 00:23:10,420 --> 00:23:12,100 CHIRPS 196 00:23:13,540 --> 00:23:16,820 And since they aren't strong enough fliers to leave the island, 197 00:23:16,820 --> 00:23:21,060 they've had to find food from a very unusual source. 198 00:23:23,900 --> 00:23:27,740 They depend on another of the island's inhabitants. 199 00:23:27,740 --> 00:23:28,940 BIRD CALLS 200 00:23:34,140 --> 00:23:36,060 Nazca boobies. 201 00:23:40,940 --> 00:23:44,060 Every day, these sea birds commute 202 00:23:44,060 --> 00:23:47,620 between the island and their fishing grounds out in the open ocean. 203 00:23:51,540 --> 00:23:54,460 Each time a pair meet, they renew their bond. 204 00:23:57,540 --> 00:24:00,940 And then catch up with the neighbours. 205 00:24:00,940 --> 00:24:03,260 CAWING AND CHIRPING 206 00:24:06,740 --> 00:24:08,140 Now is the time... 207 00:24:09,460 --> 00:24:11,060 ...to hop into action. 208 00:24:20,300 --> 00:24:22,380 CHIRPING 209 00:24:33,340 --> 00:24:34,780 Blood. 210 00:24:36,980 --> 00:24:40,980 They are vampire finches. 211 00:24:45,420 --> 00:24:50,580 These little birds have become one of the world's newest species. 212 00:24:55,740 --> 00:24:58,020 She cuts the quill of a large flight feather, 213 00:24:58,020 --> 00:25:00,140 and the blood flows. 214 00:25:03,660 --> 00:25:07,260 The sight of it attracts the attention of others. 215 00:25:09,180 --> 00:25:12,140 CAWING AND CHIRPING 216 00:25:13,420 --> 00:25:18,420 Blood is very nutritious - worth fighting for. 217 00:25:31,500 --> 00:25:34,940 So with this never-ending supply of food, 218 00:25:34,940 --> 00:25:37,780 the vampire finches can flourish on an island 219 00:25:37,780 --> 00:25:40,780 where otherwise they could not survive. 220 00:25:46,100 --> 00:25:50,300 Why the boobies don't object, nobody knows. 221 00:25:53,540 --> 00:25:56,420 Perhaps the finches' behaviour started 222 00:25:56,420 --> 00:26:00,300 when they helped the boobies to remove parasites from their plumage. 223 00:26:03,180 --> 00:26:06,140 Maybe the boobies think that the little vampires 224 00:26:06,140 --> 00:26:08,580 are still providing a service. 225 00:26:08,580 --> 00:26:10,140 Who can tell? 226 00:26:15,740 --> 00:26:19,420 Volcanic islands don't last forever. 227 00:26:19,420 --> 00:26:24,700 Changes deep in the Earth's crust bring their eruptions to an end 228 00:26:24,700 --> 00:26:28,300 and the forces of erosion then begin to wear them down. 229 00:26:35,660 --> 00:26:37,700 BIRDS TWEETING 230 00:26:37,700 --> 00:26:40,940 But the coral around them continues to grow, 231 00:26:40,940 --> 00:26:44,940 sea levels change, and eventually all that is left 232 00:26:44,940 --> 00:26:50,860 is a ring-shaped island of coral rock surrounding a lagoon. 233 00:26:50,860 --> 00:26:52,500 An atoll. 234 00:27:02,900 --> 00:27:06,500 There are hundreds of atolls in tropical seas, 235 00:27:06,500 --> 00:27:10,140 all remnants of vanished volcanoes. 236 00:27:16,900 --> 00:27:19,820 This is one of the largest and most pristine - 237 00:27:19,820 --> 00:27:22,860 Aldabra, in the Indian Ocean. 238 00:27:25,620 --> 00:27:28,980 20 million years ago, it was an island 239 00:27:28,980 --> 00:27:31,540 with a volcanic crater in its centre. 240 00:27:36,980 --> 00:27:39,100 Now, it's an atoll. 241 00:27:40,580 --> 00:27:44,580 Mangroves took root and sea birds came to nest. 242 00:27:47,380 --> 00:27:50,380 One land animal in particular... GRUNTS 243 00:27:50,380 --> 00:27:52,420 ..reached here before man. 244 00:27:52,420 --> 00:27:54,420 GRUNTS 245 00:27:55,860 --> 00:27:57,700 A giant tortoise. 246 00:27:59,020 --> 00:28:01,140 These creatures can float 247 00:28:01,140 --> 00:28:05,620 and live without food or fresh water for long periods of time. 248 00:28:09,900 --> 00:28:13,540 This isolated atoll is the perfect refuge. 249 00:28:14,580 --> 00:28:17,100 Their only enemy is the sun. 250 00:28:22,900 --> 00:28:27,980 Without shade, a tortoise risks being boiled in his shell. 251 00:28:32,460 --> 00:28:35,900 So, after feeding in the cool of the morning, 252 00:28:35,900 --> 00:28:38,940 and before the sun becomes too crushingly hot, 253 00:28:38,940 --> 00:28:40,740 they have to find cover. 254 00:28:42,180 --> 00:28:43,420 All of them. 255 00:28:49,740 --> 00:28:54,260 There is very little vegetation, but caves in the coral rock 256 00:28:54,260 --> 00:28:56,820 can provide the shade they so badly need. 257 00:29:04,900 --> 00:29:07,620 He's nearly there. 258 00:29:07,620 --> 00:29:12,660 All that is left is a white-knuckle ride to the bottom. 259 00:29:12,660 --> 00:29:15,100 GRUNTS 260 00:29:16,380 --> 00:29:18,340 And he's in. 261 00:29:22,100 --> 00:29:24,620 Thousands of others are still out in the sun. 262 00:29:26,260 --> 00:29:30,940 This tree could shade a couple of hundred, if they pack tight. 263 00:29:46,180 --> 00:29:48,180 It's bumper-to-bumper parking. 264 00:29:54,180 --> 00:29:58,140 Within an hour or so, all must find shade of some sort 265 00:29:58,140 --> 00:29:59,940 if they're to survive. 266 00:30:33,500 --> 00:30:35,100 Safe. 267 00:30:35,100 --> 00:30:37,300 GRUNTS 268 00:30:37,300 --> 00:30:42,140 But the future for Aldabra's tortoises is far from certain. 269 00:30:43,700 --> 00:30:47,940 The climate is changing, sea levels are rising, 270 00:30:47,940 --> 00:30:52,620 and Aldabra's tortoises may soon have to find a new refuge, 271 00:30:52,620 --> 00:30:54,500 or drown. 272 00:31:00,940 --> 00:31:05,220 In some places, volcanoes erupt not in the ocean 273 00:31:05,220 --> 00:31:08,220 but in the very middle of a continent. 274 00:31:12,100 --> 00:31:14,140 North America. 275 00:31:14,140 --> 00:31:18,980 And in its very heart, a volcanic hot spot - Yellowstone. 276 00:31:26,180 --> 00:31:28,780 The last major eruption here 277 00:31:28,780 --> 00:31:33,700 came to an end about 650,000 years ago, 278 00:31:33,700 --> 00:31:37,260 but this volcano is only sleeping. 279 00:31:39,140 --> 00:31:42,540 Not far below ground, there is still magma. 280 00:31:44,020 --> 00:31:47,500 And that heats the ground water to boiling point. 281 00:31:50,660 --> 00:31:52,420 BOOM 282 00:31:52,420 --> 00:31:54,340 Geysers. 283 00:31:57,420 --> 00:32:03,180 Some spout boiling water and steam to heights of 90 metres or so. 284 00:32:05,140 --> 00:32:09,980 Elsewhere, the scalding waters liquefy the ground sediments, 285 00:32:09,980 --> 00:32:12,900 creating pots of boiling mud. 286 00:32:18,860 --> 00:32:24,580 And this underground heating has proved a lifeline for some. 287 00:32:30,780 --> 00:32:32,540 River otters. 288 00:32:32,540 --> 00:32:33,940 SQUEAKS 289 00:32:36,420 --> 00:32:40,020 They need a constant supply of food if they're to keep warm 290 00:32:40,020 --> 00:32:42,700 in these freezing temperatures. 291 00:32:47,140 --> 00:32:51,420 And this close-knit family know exactly where to find it. 292 00:33:08,700 --> 00:33:12,580 The springs are so hot that the rivers never freeze, 293 00:33:12,580 --> 00:33:14,780 even in the coldest winters. 294 00:33:18,340 --> 00:33:19,900 SQUEAKS 295 00:33:19,900 --> 00:33:23,740 So the otter family can fish the year round. 296 00:33:40,580 --> 00:33:42,980 GROWLING 297 00:33:42,980 --> 00:33:44,780 Trouble. 298 00:33:46,940 --> 00:33:49,700 This coyote knows that in the middle of winter, 299 00:33:49,700 --> 00:33:53,180 a thermal river means otters, 300 00:33:53,180 --> 00:33:55,820 and otters mean fish. 301 00:34:00,940 --> 00:34:04,740 The question is how to steal their catch. 302 00:34:28,860 --> 00:34:32,620 Perhaps the thing to do is to pretend you're not interested... 303 00:34:34,220 --> 00:34:39,020 ..and hope that they wander close enough for a snatch-and-run raid. 304 00:34:51,220 --> 00:34:54,020 It seems the cool-under-fire otters 305 00:34:54,020 --> 00:34:57,580 can outwit the not-so-wily coyote. 306 00:35:08,980 --> 00:35:11,980 Many animals benefit from the volcanic heat 307 00:35:11,980 --> 00:35:14,300 coming up from below. 308 00:35:14,300 --> 00:35:17,060 OTTERS CALL 309 00:35:17,060 --> 00:35:22,380 And we do as well, but not nearly as much as we could. 310 00:35:25,180 --> 00:35:27,820 The volcanic heat could provide us 311 00:35:27,820 --> 00:35:30,460 with much of the energy that we need, 312 00:35:30,460 --> 00:35:33,540 and then we could stop burning gas and coal 313 00:35:33,540 --> 00:35:36,980 that is now changing the climate worldwide. 314 00:35:47,980 --> 00:35:50,020 Deep in the Earth's crust, 315 00:35:50,020 --> 00:35:52,860 below both the oceans and the continents, 316 00:35:52,860 --> 00:35:57,300 there are lines of weakness along which rises liquid rock. 317 00:36:02,300 --> 00:36:06,620 The Kamchatka Peninsula in the north-west Pacific 318 00:36:06,620 --> 00:36:08,620 lies along one of them. 319 00:36:23,100 --> 00:36:26,780 There are only a thousand known geysers in the world, 320 00:36:26,780 --> 00:36:30,940 and many of them are here in this isolated valley. 321 00:36:32,660 --> 00:36:35,460 BOOM 322 00:36:43,380 --> 00:36:47,060 Steam from superheated water fills the air. 323 00:36:48,380 --> 00:36:52,540 But the danger from the scalding pools does little to deter 324 00:36:52,540 --> 00:36:55,780 Kamchatka's most famous residents. 325 00:37:02,700 --> 00:37:04,580 GRUNTS 326 00:37:04,580 --> 00:37:09,220 In May, when the rest of Kamchatka is still covered by snow, 327 00:37:09,220 --> 00:37:10,980 this valley is free of it, 328 00:37:10,980 --> 00:37:15,900 and bears, having just woken up from their winter sleep, know that. 329 00:37:23,180 --> 00:37:26,700 The grass is fertilised by mineral-rich water 330 00:37:26,700 --> 00:37:28,540 spraying from the geysers. 331 00:37:31,180 --> 00:37:34,420 Much-needed forage for a large male bear 332 00:37:34,420 --> 00:37:37,420 that hasn't eaten for several months. 333 00:37:42,940 --> 00:37:45,340 And he's not the only one. 334 00:37:56,500 --> 00:38:00,020 The bears haven't seen one another for seven months, 335 00:38:00,020 --> 00:38:01,820 since the start of winter. 336 00:38:04,460 --> 00:38:08,700 And it seems that right now, they would prefer to keep it that way. 337 00:38:10,340 --> 00:38:14,980 Nothing should come between a bear and his first meal of the year. 338 00:38:20,100 --> 00:38:23,260 And in one place, Kamchatka's underground forces 339 00:38:23,260 --> 00:38:26,780 provide its bears with even more nutritious meals. 340 00:38:34,740 --> 00:38:38,700 Kurile Lake lies within the crater of an immense volcano 341 00:38:38,700 --> 00:38:42,220 that long ago produced one of the greatest eruptions 342 00:38:42,220 --> 00:38:44,020 in the planet's history. 343 00:38:47,500 --> 00:38:50,740 The lake is still circled by active vents... 344 00:38:53,100 --> 00:38:56,860 ..and mineral-rich ash from their regular eruptions 345 00:38:56,860 --> 00:38:59,900 has made these waters particularly fertile. 346 00:39:03,220 --> 00:39:06,620 Millions of salmon come here from the Pacific Ocean 347 00:39:06,620 --> 00:39:09,500 in order to spawn in these fertile waters, 348 00:39:09,500 --> 00:39:13,300 which will provide their newly hatched young with abundant food. 349 00:39:19,620 --> 00:39:25,300 So, grass soon ceases to be top of the menu for Kamchatka's bears. 350 00:39:28,580 --> 00:39:31,220 By the time spring has turned to summer, 351 00:39:31,220 --> 00:39:35,660 Kurile Lake contains the most dense assembly of bears 352 00:39:35,660 --> 00:39:38,500 to be found anywhere on Earth. 353 00:39:43,740 --> 00:39:46,140 All hungry for salmon. 354 00:39:53,940 --> 00:39:57,020 SEA BIRDS CALL 355 00:39:57,020 --> 00:40:02,100 But this early in the season, the fish are still strong and swift. 356 00:40:18,140 --> 00:40:20,340 Nothing seems to work. 357 00:40:28,500 --> 00:40:31,820 But one old bear knows that, right now, 358 00:40:31,820 --> 00:40:34,340 there is an easier meal to be had. 359 00:40:38,180 --> 00:40:41,580 He remembers that if he paddles out into the lake, 360 00:40:41,580 --> 00:40:44,940 away from the shoals of newly arrived salmon, 361 00:40:44,940 --> 00:40:48,380 there's food that doesn't need chasing. 362 00:41:07,540 --> 00:41:10,740 Some of the first fish to arrive have died, 363 00:41:10,740 --> 00:41:12,980 and their bodies can be easily collected... 364 00:41:12,980 --> 00:41:14,380 BEAR GRUNTS 365 00:41:14,380 --> 00:41:16,180 ..from the bottom of the lake. 366 00:41:22,340 --> 00:41:27,380 Diving for them at leisure doesn't use many calories. 367 00:41:32,460 --> 00:41:35,260 And he can take his time. 368 00:41:47,900 --> 00:41:49,940 A couple of weeks later, 369 00:41:49,940 --> 00:41:53,580 the salmon are beginning to spawn and are less wary. 370 00:41:56,220 --> 00:41:59,060 Now it's worth running. 371 00:42:15,700 --> 00:42:17,940 The fish are so abundant... 372 00:42:20,020 --> 00:42:21,980 ..that there is plenty for all... 373 00:42:23,860 --> 00:42:26,660 ..even those with no previous experience. 374 00:42:30,740 --> 00:42:33,060 There are now so many fish, 375 00:42:33,060 --> 00:42:36,540 it's difficult to know which one to chase. 376 00:42:51,700 --> 00:42:57,140 In a single day, a bear can consume 100,000 calories, 377 00:42:57,140 --> 00:43:00,780 50 times more than the average human being does. 378 00:43:02,220 --> 00:43:06,260 And one part is particularly delicious... 379 00:43:10,380 --> 00:43:12,220 ..caviar. 380 00:43:12,220 --> 00:43:15,020 80 calories in every mouthful. 381 00:43:20,700 --> 00:43:23,020 BEARS GRUNT 382 00:43:23,020 --> 00:43:26,860 By supporting huge concentrations of salmon, 383 00:43:26,860 --> 00:43:30,780 mineral ash from Kurile Lake's volcanoes 384 00:43:30,780 --> 00:43:34,500 has made life surprisingly easy for these bears. 385 00:43:38,780 --> 00:43:41,020 EXPLOSIVE BOOM 386 00:43:48,540 --> 00:43:52,900 Our planet depends on minerals brought up by volcanoes 387 00:43:52,900 --> 00:43:55,220 from the Earth's molten core. 388 00:43:58,740 --> 00:44:03,780 A single ash cloud can carry billions of tonnes of minerals. 389 00:44:17,420 --> 00:44:21,260 And as a consequence, the lands surrounding volcanoes 390 00:44:21,260 --> 00:44:23,660 are among the world's most fertile. 391 00:44:29,140 --> 00:44:31,940 Those in East Africa's Rift Valley 392 00:44:31,940 --> 00:44:35,660 support the most dynamic ecosystem on Earth. 393 00:44:41,100 --> 00:44:42,940 The Serengeti. 394 00:44:47,220 --> 00:44:52,260 This is the most productive of all natural grasslands anywhere. 395 00:44:54,380 --> 00:44:57,060 Every year, over a million wildebeest 396 00:44:57,060 --> 00:45:00,620 assemble in this particular corner of the Serengeti 397 00:45:00,620 --> 00:45:06,180 to feed on grass especially rich in calcium and phosphorus, 398 00:45:06,180 --> 00:45:09,780 essential minerals for the pregnant females. 399 00:45:12,300 --> 00:45:16,100 In just three weeks, half a million calves are born 400 00:45:16,100 --> 00:45:18,860 on these ash-rich plains. 401 00:45:20,980 --> 00:45:24,460 That's 24,000 a day... 402 00:45:24,460 --> 00:45:27,060 ..a thousand an hour. 403 00:45:30,820 --> 00:45:34,180 Calves stand up within a few minutes of being born. 404 00:45:37,940 --> 00:45:41,900 Though some need a little more time to find their feet. 405 00:45:54,300 --> 00:45:56,740 But a mother won't let her calf suckle 406 00:45:56,740 --> 00:46:00,180 until it's mastered a few physical skills... 407 00:46:03,140 --> 00:46:04,820 ..walking... 408 00:46:05,860 --> 00:46:07,180 ..trotting... 409 00:46:09,100 --> 00:46:10,860 ..and running. 410 00:46:16,260 --> 00:46:18,260 WILDEBEEST SNORT 411 00:46:20,460 --> 00:46:25,140 Wildebeest calves must run if they're to stay alive. 412 00:46:27,900 --> 00:46:29,740 HYENA CACKLES 413 00:46:40,420 --> 00:46:43,220 For these plains also support 414 00:46:43,220 --> 00:46:47,780 the greatest assembly of hunters on the planet. 415 00:46:50,980 --> 00:46:54,420 Each species has its own special hunting technique. 416 00:46:55,700 --> 00:46:57,940 But all have the same aim... 417 00:47:00,620 --> 00:47:05,580 ..to make the most of this brief super-abundance of life. 418 00:47:34,380 --> 00:47:37,740 PANTING 419 00:47:39,900 --> 00:47:42,220 HEARTBEAT THUMPING 420 00:48:03,860 --> 00:48:10,620 Only one in ten wildebeest calves will survive to adulthood. 421 00:48:10,620 --> 00:48:15,100 But that is enough to maintain the million-strong herd of wildebeest... 422 00:48:15,100 --> 00:48:17,100 HYENA WAILS 423 00:48:17,100 --> 00:48:20,540 ...AND the planet's highest density of predators. 424 00:48:23,940 --> 00:48:26,700 Volcanoes fertilise the planet, 425 00:48:26,700 --> 00:48:29,900 but they're the source of something else so important 426 00:48:29,900 --> 00:48:33,100 that life could not have started without it. 427 00:48:38,020 --> 00:48:41,940 The first carbon dioxide in the Earth's atmosphere 428 00:48:41,940 --> 00:48:46,420 was brought by volcanoes from deep in the Earth's crust. 429 00:48:48,380 --> 00:48:50,020 BIRDS CALL 430 00:48:50,020 --> 00:48:54,060 And this gas is the foundation of life. 431 00:48:54,060 --> 00:48:56,860 Every plant needs it to grow, 432 00:48:56,860 --> 00:48:59,340 and absorbs it from the air. 433 00:49:02,420 --> 00:49:06,220 Volcanoes continue to release carbon dioxide today, 434 00:49:06,220 --> 00:49:09,020 and for the last 10,000 years, 435 00:49:09,020 --> 00:49:13,900 its presence in the atmosphere has suited life perfectly. 436 00:49:16,780 --> 00:49:19,460 Its greenhouse properties have kept 437 00:49:19,460 --> 00:49:22,660 our planet's climate stable and warm. 438 00:49:27,500 --> 00:49:29,700 EXPLOSIVE BOOM 439 00:49:29,700 --> 00:49:33,340 But too much carbon dioxide would make the planet's temperature 440 00:49:33,340 --> 00:49:35,980 rise to levels that would upset the Earth's 441 00:49:35,980 --> 00:49:40,180 long-established ecological balances. 442 00:49:40,180 --> 00:49:41,980 EXPLOSIVE BOOM 443 00:49:55,460 --> 00:49:58,060 Today, humanity itself 444 00:49:58,060 --> 00:50:01,900 has become a new kind of supervolcano. 445 00:50:01,900 --> 00:50:04,740 EXPLOSIVE BOOM 446 00:50:08,420 --> 00:50:13,500 Now, every year, we ourselves release 100 times more carbon 447 00:50:13,500 --> 00:50:16,420 than all the Earth's volcanoes combined. 448 00:50:17,940 --> 00:50:21,380 And that has brought climate chaos. 449 00:50:25,740 --> 00:50:28,740 We can't control volcanoes, 450 00:50:28,740 --> 00:50:33,820 but we can limit the amount of carbon dioxide that we produce. 451 00:50:35,300 --> 00:50:38,380 And if we do that, there will still be time 452 00:50:38,380 --> 00:50:41,340 to restore the ecological balance 453 00:50:41,340 --> 00:50:45,460 that once made this Earth our perfect planet. 454 00:50:57,580 --> 00:50:59,620 DAVID ATTENBOROUGH: Lake Natron, in Tanzania 455 00:50:59,620 --> 00:51:04,100 is one of the world's most toxic bodies of water. 456 00:51:04,100 --> 00:51:07,740 Yet once every few years, when the centre dries out, 457 00:51:07,740 --> 00:51:12,100 it's brought to life by thousands of breeding flamingos. 458 00:51:16,020 --> 00:51:17,980 But to reach the colony, 459 00:51:17,980 --> 00:51:21,300 there's only one way to cross this soft soda sludge. 460 00:51:23,700 --> 00:51:25,860 It's finally here. 461 00:51:25,860 --> 00:51:27,740 Our secret weapon... 462 00:51:27,740 --> 00:51:30,260 ..is a hovercraft. 463 00:51:31,460 --> 00:51:33,700 And it's beautiful. 464 00:51:33,700 --> 00:51:35,660 Having shipped it from the UK, 465 00:51:35,660 --> 00:51:39,180 Darren's keen to test that all systems are go. 466 00:51:39,180 --> 00:51:42,100 ENGINE REVS 467 00:51:42,100 --> 00:51:44,740 Getting it off the trailer is one thing, 468 00:51:44,740 --> 00:51:47,460 but at least the hovercraft's fans, that give it lift, 469 00:51:47,460 --> 00:51:49,420 are working well enough. 470 00:52:02,460 --> 00:52:04,980 COUGHING AND LAUGHTER 471 00:52:04,980 --> 00:52:07,060 Well, guys, what do you think? 472 00:52:07,060 --> 00:52:09,860 We know she works, but... COUGHING 473 00:52:09,860 --> 00:52:12,700 ..maybe some of these guys' lungs don't now. 474 00:52:12,700 --> 00:52:17,260 125 miles away, on the edge of Lake Natron, 475 00:52:17,260 --> 00:52:21,060 cameraman Matt Aeberhard is trying to camouflage his hides. 476 00:52:22,500 --> 00:52:24,540 Those are our blinds. 477 00:52:24,540 --> 00:52:26,980 So, you can't camouflage those on the flats, 478 00:52:26,980 --> 00:52:29,420 and the best thing that we can do is actually 479 00:52:29,420 --> 00:52:31,580 turn them into a little cluster of flamingos. 480 00:52:37,540 --> 00:52:39,980 It's pretty cool, huh? 481 00:52:39,980 --> 00:52:45,220 Hide complete, all that's needed is transport out to the colony. 482 00:52:45,220 --> 00:52:47,980 And after a ten-hour cross-country journey, 483 00:52:47,980 --> 00:52:51,100 Darren arrives with his secret weapon... 484 00:52:51,100 --> 00:52:54,060 ..and it's an instant hit. 485 00:52:54,060 --> 00:52:55,980 It's the new local tourist attraction. 486 00:52:57,420 --> 00:52:59,660 You like it? 487 00:52:59,660 --> 00:53:02,700 The first job is to get the hovercraft into service 488 00:53:02,700 --> 00:53:05,700 and plot a route out to the nesting flamingos. 489 00:53:21,140 --> 00:53:24,300 The volcanic spring water is soon replaced 490 00:53:24,300 --> 00:53:27,060 by a crust of razor-sharp salt crystals. 491 00:53:28,220 --> 00:53:32,620 And for a machine that relies on a delicate blow-up bottom, 492 00:53:32,620 --> 00:53:34,380 that's a problem. 493 00:53:34,380 --> 00:53:37,260 So, what we have here are the plates of dried out soda 494 00:53:37,260 --> 00:53:39,860 which form on the mud substrate underneath, 495 00:53:39,860 --> 00:53:42,540 and it just batters the hovercraft. 496 00:53:42,540 --> 00:53:44,940 We just cannot travel across this stuff. 497 00:53:44,940 --> 00:53:46,780 It's impossible. 498 00:53:46,780 --> 00:53:51,500 If I was to skim my hand across that, I would cut it to shreds. 499 00:53:53,260 --> 00:53:57,260 But crossing the soda crust is the only way out of to the colonies, 500 00:53:57,260 --> 00:54:00,140 and so Matt and Darren have to hope for the best. 501 00:54:00,140 --> 00:54:02,540 DRILL WHIRS 502 00:54:02,540 --> 00:54:04,060 Unfortunately for Matt, 503 00:54:04,060 --> 00:54:06,740 the best position for his flamingo-covered hide 504 00:54:06,740 --> 00:54:09,740 has a rather soggy floor. 505 00:54:09,740 --> 00:54:13,620 When the mud dries, it leaves massive amounts of salt. 506 00:54:13,620 --> 00:54:17,420 Very scratchy, nasty and aggressive salt. 507 00:54:19,100 --> 00:54:22,700 But sitting shin-deep in toxic sludge 508 00:54:22,700 --> 00:54:26,420 is a price worth paying for the view. 509 00:54:26,420 --> 00:54:29,700 And Matt is soon rewarded with the birth of a chick 510 00:54:29,700 --> 00:54:32,180 right in front of his hide. 511 00:54:43,020 --> 00:54:45,300 CHICK CHIRPS 512 00:54:48,100 --> 00:54:50,140 The daily commute, however, 513 00:54:50,140 --> 00:54:53,100 is taking its toll on the hovercraft... 514 00:54:53,100 --> 00:54:54,980 ENGINE STALLS 515 00:54:54,980 --> 00:54:57,500 Oh, come on! 516 00:54:57,500 --> 00:55:01,740 ..and its blow-up bottom is literally being ripped apart. 517 00:55:01,740 --> 00:55:06,380 We've trashed 52 of these that now need to be repaired. 518 00:55:06,380 --> 00:55:08,900 It's like travelling over sandpaper. 519 00:55:08,900 --> 00:55:11,900 So, what do you do when your hovercraft needs 520 00:55:11,900 --> 00:55:15,100 replacement skirts and you're in the middle of nowhere? 521 00:55:16,940 --> 00:55:19,820 Enter the local Maasai tribe, 522 00:55:19,820 --> 00:55:22,660 well known for their needlework skills. 523 00:55:22,660 --> 00:55:25,260 There are only a few places in the world that specialise 524 00:55:25,260 --> 00:55:27,820 in hovercraft maintenance, 525 00:55:27,820 --> 00:55:31,220 and Lake Natron is now officially one of those hot spots. 526 00:55:31,220 --> 00:55:33,540 So if you're in the need of any hovercraft services, 527 00:55:33,540 --> 00:55:35,420 you know where to go. 528 00:55:37,500 --> 00:55:40,940 Two days later, and after a lot of serious sewing, 529 00:55:40,940 --> 00:55:44,140 the hovercraft is ready to ride again. 530 00:55:44,140 --> 00:55:47,260 ENGINE TURNS OVER 531 00:55:47,260 --> 00:55:50,260 You look like the new Tanzanian bobsleigh team! 532 00:55:55,180 --> 00:55:58,700 And getting back on the lake couldn't have come at a better time, 533 00:55:58,700 --> 00:56:01,020 as the chicks are now on the move. 534 00:56:02,900 --> 00:56:06,340 Sadly, the new hide position is no drier. 535 00:56:08,980 --> 00:56:14,260 We have an enormous creche of hundreds of thousands of birds 536 00:56:14,260 --> 00:56:17,740 just pouring into the lagoon from the salt mud, 537 00:56:17,740 --> 00:56:20,500 just constantly chatting to each other. 538 00:56:22,180 --> 00:56:26,380 But the massive creche attracts some unwelcome visitors... 539 00:56:27,820 --> 00:56:31,300 ...predators - marabou storks. 540 00:56:35,980 --> 00:56:39,420 These marabous, they know exactly what they are doing. 541 00:56:43,500 --> 00:56:47,060 Soon, thousands of panicked chicks are on the move, 542 00:56:47,060 --> 00:56:49,820 desperately trying to avoid the predators. 543 00:57:04,420 --> 00:57:09,020 And it's a scene that will live long in Matt's memory. 544 00:57:10,300 --> 00:57:13,620 I mean, it was literally like... 545 00:57:13,620 --> 00:57:15,340 ..war had been declared. 546 00:57:16,380 --> 00:57:19,820 I mean, that's one of the...the... 547 00:57:19,820 --> 00:57:25,420 ...most amazing and frightening and freaky wildlife scenes 548 00:57:25,420 --> 00:57:27,860 I've ever, EVER seen. 549 00:57:27,860 --> 00:57:31,500 And believe me, I've seen a few. 550 00:57:31,500 --> 00:57:35,540 And few places are more challenging than Lake Natron, 551 00:57:35,540 --> 00:57:38,380 but to quote Matt, if you can deal with 552 00:57:38,380 --> 00:57:41,580 the acrid and sulphurous stink of the soda, 553 00:57:41,580 --> 00:57:45,860 the stinging eyes and the chemical attack on your legs, 554 00:57:45,860 --> 00:57:51,100 then you could be rewarded with one of the greatest spectacles on Earth. 555 00:57:55,700 --> 00:57:57,620 Next time... 556 00:57:57,620 --> 00:58:00,180 ..the sun. 557 00:58:00,180 --> 00:58:04,100 Life on our planet is fuelled by its energy. 558 00:58:08,940 --> 00:58:11,820 Everything must be perfectly tuned 559 00:58:11,820 --> 00:58:16,700 to the daily and yearly rhythms of this vital force. 560 00:58:20,620 --> 00:58:23,620 The Open University has produced a free poster 561 00:58:23,620 --> 00:58:26,100 exploring our perfect planet. 562 00:58:26,100 --> 00:58:31,380 To order, please call 0300 303 0901. 563 00:58:31,380 --> 00:58:36,060 Or go to bbc.co.uk/perfectplanet 564 00:58:36,060 --> 00:58:39,060 and follow the links to the Open University.