1 00:00:44,962 --> 00:00:47,506 In the course of making Blue Planet II, 2 00:00:47,632 --> 00:00:51,302 we've explored every corner of the underwater world. 3 00:00:53,804 --> 00:00:56,891 We've encountered extraordinary animals, 4 00:01:03,564 --> 00:01:08,986 and discovered new insights into how life is lived beneath the waves. 5 00:01:15,326 --> 00:01:19,622 For years we thought that the oceans were so vast 6 00:01:19,705 --> 00:01:23,167 and the inhabitants so infinitely numerous 7 00:01:23,251 --> 00:01:26,921 that nothing we could do could have an effect upon them. 8 00:01:27,004 --> 00:01:29,173 But now we know that was wrong. 9 00:01:30,049 --> 00:01:35,680 The oceans are under threat now as never before in human history. 10 00:01:37,348 --> 00:01:39,350 In this final episode, 11 00:01:39,433 --> 00:01:44,772 we will meet the pioneers who are striving to turn things around. 12 00:01:49,735 --> 00:01:54,865 People who are helping to save the ocean's most vulnerable inhabitants 13 00:01:57,285 --> 00:02:01,706 and dedicating their lives to protecting the seas. 14 00:02:04,709 --> 00:02:07,044 But is time running out? 15 00:02:09,213 --> 00:02:13,884 Many people believe that our oceans have reached a crisis point. 16 00:02:14,385 --> 00:02:18,389 So just how fragile is our blue planet? 17 00:02:34,655 --> 00:02:37,742 Winter in the Arctic Circle. 18 00:02:40,119 --> 00:02:43,664 Every year, the waters of Norway are the setting 19 00:02:43,748 --> 00:02:47,418 for one of the greatest wildlife spectacles in the ocean. 20 00:02:48,836 --> 00:02:53,424 Over a billion herring pour into these fields. 21 00:02:55,593 --> 00:02:58,596 The Blue Planet II team spent three years 22 00:02:58,679 --> 00:03:01,307 documenting this astonishing event. 23 00:03:05,936 --> 00:03:09,482 Such a wealth of prey attracts predators 24 00:03:09,607 --> 00:03:11,692 in extraordinary numbers. 25 00:03:15,112 --> 00:03:16,614 Orcas 26 00:03:21,827 --> 00:03:23,829 and humpback whales. 27 00:03:45,309 --> 00:03:49,897 But this migration hasn't always been so bountiful. 28 00:03:50,856 --> 00:03:54,985 Leif Notastad is a Norwegian fisheries scientist. 29 00:03:55,861 --> 00:03:58,739 It's been one of the most important fisheries 30 00:03:58,864 --> 00:04:02,701 that we had for centuries along the whole coast of Norway. 31 00:04:02,827 --> 00:04:04,870 But in the late 1960s 32 00:04:04,995 --> 00:04:08,916 the herrings that we see around us here was on the brink of collapse. 33 00:04:13,921 --> 00:04:17,049 50 years ago, fishing was so intensive 34 00:04:17,174 --> 00:04:19,927 that the herring had all but disappeared. 35 00:04:22,388 --> 00:04:24,723 Orcas were seen as rivals 36 00:04:24,849 --> 00:04:27,017 and hundreds of them were killed. 37 00:04:34,233 --> 00:04:38,779 It was only after the Norwegian government imposed severe restrictions 38 00:04:38,863 --> 00:04:41,198 that the herring began to recover. 39 00:04:47,955 --> 00:04:52,918 Today, this is once again an immensely productive fishery, 40 00:04:53,878 --> 00:04:57,381 closely monitored by teams of scientists. 41 00:05:01,260 --> 00:05:03,679 Marine biologist Eve Jourdain 42 00:05:03,762 --> 00:05:06,891 is one of the resident orca experts. 43 00:05:07,475 --> 00:05:10,603 From 1982, orcas got protected in Norway 44 00:05:10,728 --> 00:05:15,566 and we have clearly one of the largest orca population in the world out here. 45 00:05:18,068 --> 00:05:20,988 There are now over a thousand orcas here. 46 00:05:21,238 --> 00:05:24,825 But with so many mouths to feed, including ours, 47 00:05:24,909 --> 00:05:27,620 can the mistakes of the past be avoided? 48 00:05:29,997 --> 00:05:32,291 To answer this vital question, 49 00:05:32,416 --> 00:05:36,587 Eve and her team are using multi sensor camera tags. 50 00:05:38,923 --> 00:05:44,803 With the tags we try to see how the orcas interact with their prey. 51 00:05:44,929 --> 00:05:48,557 How they hunt and all about the underwater behaviour 52 00:05:48,641 --> 00:05:51,018 that we are not able to see from the boat. 53 00:05:53,437 --> 00:05:55,689 A tag has to be attached 54 00:05:55,773 --> 00:05:58,108 to the orca in exactly the right position. 55 00:06:01,278 --> 00:06:03,614 Here it goes. Here it comes. 56 00:06:08,202 --> 00:06:09,954 Oh, that's a good shot. 57 00:06:14,458 --> 00:06:17,545 It is the least invasive method. It is suction cups. 58 00:06:17,711 --> 00:06:20,256 So it is not a scratch on the whale afterwards 59 00:06:20,339 --> 00:06:22,132 which is something we really like. 60 00:06:25,636 --> 00:06:27,555 While studying the orcas, 61 00:06:27,638 --> 00:06:31,308 Eve noticed a worrying change in their behaviour. 62 00:06:32,309 --> 00:06:35,646 They had worked out the easiest way to get a meal. 63 00:06:37,064 --> 00:06:39,400 We have seen that the orcas are waiting 64 00:06:39,483 --> 00:06:42,069 for those fishing boats to drop the net. 65 00:06:43,571 --> 00:06:45,531 It acts like a dinner bell 66 00:06:45,656 --> 00:06:48,576 and then all the orcas of the area gather. 67 00:06:49,577 --> 00:06:51,412 Quite a lot of herring slip from the net 68 00:06:51,495 --> 00:06:54,248 and this is exactly what the orcas are looking for. 69 00:06:57,835 --> 00:07:02,256 But this new tactic is dangerous, as Eve has witnessed. 70 00:07:03,591 --> 00:07:06,719 We were there to monitor the behaviour of the orcas 71 00:07:06,844 --> 00:07:09,054 scavenging around the nets. 72 00:07:09,179 --> 00:07:12,266 And we realised that one large adult male 73 00:07:12,349 --> 00:07:14,518 was actually trapped inside the net. 74 00:07:15,603 --> 00:07:17,980 When the fishermen started to retrieve the net 75 00:07:18,063 --> 00:07:20,774 the orca was obviously starting to panic 76 00:07:20,858 --> 00:07:24,153 and trying to pull as much as he could. 77 00:07:24,236 --> 00:07:26,780 This orca was really fighting for his life. 78 00:07:29,033 --> 00:07:31,452 Stringent rules require fishermen 79 00:07:31,535 --> 00:07:34,413 to get permission before they open their nets. 80 00:07:36,373 --> 00:07:37,916 But that took time. 81 00:07:43,047 --> 00:07:45,049 It was such a long process. 82 00:07:45,758 --> 00:07:50,054 We thought that the whale was going to die of exhaustion. 83 00:07:54,058 --> 00:07:56,894 Thankfully, the fishermen finally got the clearance 84 00:07:56,977 --> 00:08:00,606 to release their net freeing the exhausted orca. 85 00:08:12,409 --> 00:08:17,289 It was a huge relief to see that this orca made it until the end 86 00:08:17,414 --> 00:08:20,084 and finally got back to his family. 87 00:08:23,420 --> 00:08:27,341 With marine mammals and humans competing so directly 88 00:08:27,424 --> 00:08:29,760 accidents are inevitable. 89 00:08:34,348 --> 00:08:36,934 Two days after tagging an orca, 90 00:08:37,017 --> 00:08:39,978 it's released and Eve collects it. 91 00:08:43,607 --> 00:08:45,776 This tag is full of secrets, you know, 92 00:08:45,859 --> 00:08:48,153 because it has been on the whale for several days 93 00:08:48,278 --> 00:08:51,532 and will just reveal exactly what the whales have been doing. 94 00:08:52,199 --> 00:08:56,704 Pictures from the tag reveal the hunting technique in detail. 95 00:09:03,460 --> 00:09:06,505 They dive below the ball offish 96 00:09:09,466 --> 00:09:11,343 and then back flip. 97 00:09:14,805 --> 00:09:18,892 The tail slap stuns the herring. 98 00:09:21,478 --> 00:09:25,733 Eve can even work out how many fish the orcas are taking. 99 00:09:26,567 --> 00:09:30,696 They can kill up to 30 herring with just one tail slap. 100 00:09:30,821 --> 00:09:32,740 And then what is pretty amazing is 101 00:09:32,823 --> 00:09:35,993 all the individuals of the group share the dead herring. 102 00:09:37,661 --> 00:09:40,497 And it's not just the orcas feeding here... 103 00:09:42,750 --> 00:09:46,420 Humpback whales are also drawn to the feast. 104 00:10:00,434 --> 00:10:02,978 They too are being tagged and monitored 105 00:10:03,061 --> 00:10:05,105 giving fishery scientist Leif 106 00:10:05,189 --> 00:10:08,776 a complete picture of how much herring is being eaten. 107 00:10:09,777 --> 00:10:13,781 The whales, they take probably less than 1 %. 108 00:10:14,865 --> 00:10:18,202 The fishermen take less than 10%. 109 00:10:18,952 --> 00:10:22,915 So the balance there is that there is enough for everybody. 110 00:10:23,040 --> 00:10:26,001 Given that we manage to stock in sustainable 111 00:10:26,084 --> 00:10:28,045 and a long term sustainable way. 112 00:10:37,554 --> 00:10:42,226 But it's estimated that almost a third of ocean fisheries 113 00:10:42,309 --> 00:10:44,561 are being over exploited. 114 00:10:49,066 --> 00:10:51,902 The remarkable recovery of the herring here 115 00:10:51,985 --> 00:10:55,989 demonstrates what can happen if a fishery is carefully managed. 116 00:11:14,675 --> 00:11:17,928 Our maltreatment of the seas has many effects. 117 00:11:19,805 --> 00:11:21,515 Some are predictable, 118 00:11:22,599 --> 00:11:26,436 but there are others that are rather more surprising. 119 00:11:35,487 --> 00:11:37,281 Southeast Asia. 120 00:11:39,616 --> 00:11:43,787 The coral reefs here are among the richest on the planet. 121 00:11:54,214 --> 00:11:57,009 Marine biologist Steve Simpson, 122 00:11:57,134 --> 00:12:00,137 is discovering how important sound is 123 00:12:00,220 --> 00:12:03,807 to the animals that live in these bustling coral cities. 124 00:12:05,642 --> 00:12:08,186 We're only now just realising by listening underwater 125 00:12:08,312 --> 00:12:10,314 that the fish are making all these sounds. 126 00:12:10,647 --> 00:12:13,358 They use sound to attract a mate. 127 00:12:13,483 --> 00:12:15,694 To try and scare away a predator. 128 00:12:16,862 --> 00:12:20,866 You hear pops and grunts and gurgles and snaps. 129 00:12:23,577 --> 00:12:25,454 There's a whole language underwater 130 00:12:25,537 --> 00:12:28,040 that we're only just starting to get a handle on. 131 00:12:48,352 --> 00:12:52,481 Using an advanced multi directional hydrophone, 132 00:12:52,564 --> 00:12:56,568 Steve is trying to make sense of this extraordinary chorus 133 00:12:56,693 --> 00:13:00,530 by working out who is making which noise. 134 00:13:03,575 --> 00:13:06,703 One fish is especially talkative. 135 00:13:09,706 --> 00:13:12,876 It's perhaps the reef's most famous resident. 136 00:13:14,044 --> 00:13:15,587 The clownfish. 137 00:13:18,382 --> 00:13:20,258 While filming for the series, 138 00:13:20,384 --> 00:13:24,763 we followed this particular family of saddleback clownfish 139 00:13:24,888 --> 00:13:28,225 as they search for a suitable place to lay their eggs. 140 00:13:31,895 --> 00:13:34,314 It's a noisy affair. 141 00:13:49,746 --> 00:13:52,082 For clownfish sound really is everything. 142 00:13:52,165 --> 00:13:54,751 They spend all day talking to each other. 143 00:13:55,585 --> 00:13:57,421 You've got dominance and submission. 144 00:13:57,504 --> 00:13:59,756 You've got all the others calling to each other. 145 00:14:01,591 --> 00:14:04,636 It seems that they also use sound 146 00:14:05,846 --> 00:14:10,809 in protecting themselves from the many predators that hunt around the reef 147 00:14:16,982 --> 00:14:19,693 Including coral trout. 148 00:14:34,124 --> 00:14:38,003 Will this model trout fool the clownfish? 149 00:14:44,676 --> 00:14:47,345 They react almost immediately. 150 00:14:50,015 --> 00:14:51,558 By mimicking a predator, 151 00:14:51,641 --> 00:14:56,897 Steve manages to record their alarm calls without putting them at risk. 152 00:14:57,898 --> 00:15:01,359 You can really hear the deeper pulsing sound of the female 153 00:15:01,485 --> 00:15:03,987 as she tries to scare the coral trout away. 154 00:15:05,822 --> 00:15:08,283 And all the little ones are just popping... Pop, pop, pop. 155 00:15:08,366 --> 00:15:10,744 As if to say, "I'm still okay. I'm still alive." 156 00:15:12,662 --> 00:15:15,999 So they've got this real language of sounds that they're using 157 00:15:16,083 --> 00:15:19,377 just to try and defend the colony against this coral trout. 158 00:15:22,881 --> 00:15:26,676 But that discovery has led to a serious worry. 159 00:15:29,930 --> 00:15:33,225 The fish were really popping away at the predator. 160 00:15:33,350 --> 00:15:37,062 But as soon as the boat came over they looked completely distracted. 161 00:15:37,187 --> 00:15:40,273 With all that noise it completely changed how the fish were behaving. 162 00:15:42,025 --> 00:15:45,362 Unable to make themselves heard above the noise of boats, 163 00:15:45,445 --> 00:15:48,198 the family can't warn each other of danger. 164 00:15:48,281 --> 00:15:51,243 And so they are now vulnerable to attack. 165 00:15:52,577 --> 00:15:54,663 You think about how many boats are driving around. 166 00:15:54,746 --> 00:15:57,749 All of the ships, all of the offshore drilling. 167 00:15:57,874 --> 00:15:59,668 All the noise that we're making in the ocean 168 00:15:59,751 --> 00:16:01,753 you realise just how much we're drowning out 169 00:16:01,878 --> 00:16:03,839 this natural biological noise, 170 00:16:03,922 --> 00:16:08,051 robbing animals of their ability to be able to talk to each other. 171 00:16:12,055 --> 00:16:16,810 All this noise may have serious consequences for many reef fish 172 00:16:16,893 --> 00:16:21,231 because their babies, as soon as they hatch are swept out to sea. 173 00:16:25,318 --> 00:16:29,239 There they feed and grow until strong enough to swim back. 174 00:16:31,283 --> 00:16:35,412 And to find the reef, they use sound. 175 00:16:36,496 --> 00:16:39,583 They listen in. They eavesdrop to the noises that they can hear 176 00:16:39,666 --> 00:16:43,003 and they use that to choose which reef they want to make their home. 177 00:16:43,253 --> 00:16:45,881 But obviously because we're adding all this noise to the ocean 178 00:16:45,964 --> 00:16:48,466 it's a wonder whether they can even hear the reef at all. 179 00:16:53,930 --> 00:16:57,642 Man-made noise is now everywhere in the ocean. 180 00:16:57,767 --> 00:17:01,605 And it has an effect on marine creatures of all kinds. 181 00:17:03,773 --> 00:17:05,817 From tiny fish 182 00:17:07,527 --> 00:17:09,988 to gigantic whales. 183 00:17:13,325 --> 00:17:16,620 But Steve believes there are solutions. 184 00:17:17,287 --> 00:17:19,915 Noise in the ocean is a real problem. 185 00:17:19,998 --> 00:17:22,209 But, it's something that we can control. 186 00:17:22,292 --> 00:17:23,877 We can choose where we make the noise. 187 00:17:23,960 --> 00:17:25,962 We can choose when we make the noise. 188 00:17:26,046 --> 00:17:29,549 We can directly reduce the amount of noise that we make 189 00:17:29,633 --> 00:17:31,509 and we can start doing that today. 190 00:17:39,851 --> 00:17:42,187 We're only now beginning to realise 191 00:17:42,312 --> 00:17:46,524 what an impact our noise is having on the inhabitants of the ocean. 192 00:17:49,653 --> 00:17:52,989 Other forms of pollution are only too familiar. 193 00:18:00,247 --> 00:18:03,041 Since its invention some hundred years ago, 194 00:18:03,166 --> 00:18:07,170 plastic has become an integral part of our daily lives. 195 00:18:07,254 --> 00:18:11,049 But every year, some eight million tons of it 196 00:18:11,174 --> 00:18:13,093 ends up in the ocean. 197 00:18:13,176 --> 00:18:15,512 And there, it could be lethal. 198 00:18:21,017 --> 00:18:23,395 While filming Blue Planet II, 199 00:18:23,520 --> 00:18:27,023 the crews found plastic in every ocean. 200 00:18:28,566 --> 00:18:31,903 Even in the most remote locations. 201 00:18:36,616 --> 00:18:38,118 South Georgia. 202 00:18:40,287 --> 00:18:42,831 900 miles north of Antarctica, 203 00:18:42,914 --> 00:18:46,251 this isolated wilderness is the breeding place 204 00:18:46,376 --> 00:18:50,088 for vast numbers of penguins and elephant seals. 205 00:19:00,640 --> 00:19:03,310 It's also a favourite nesting site 206 00:19:03,393 --> 00:19:05,562 for the largest bird in the sky. 207 00:19:07,731 --> 00:19:09,733 A wandering albatross. 208 00:19:13,278 --> 00:19:15,947 Here we learn of the extraordinary lengths 209 00:19:16,072 --> 00:19:20,827 ancient parents go to give their chicks the best chance of survival. 210 00:19:23,747 --> 00:19:28,626 Each devoted parent travels thousands of miles searching for fish and squid 211 00:19:28,752 --> 00:19:30,754 to feed their hungry chick. 212 00:19:34,341 --> 00:19:36,343 But despite all their efforts, 213 00:19:36,426 --> 00:19:39,596 the albatross colony here is in trouble. 214 00:19:41,473 --> 00:19:45,935 Lucy Quinn is part of the British Antarctic Survey team 215 00:19:46,019 --> 00:19:49,647 studying the birds here for the last 40 years. 216 00:19:50,857 --> 00:19:53,068 Its only through looking at long terms studies 217 00:19:53,151 --> 00:19:55,695 that you get a sense of these creatures. 218 00:19:55,779 --> 00:20:01,117 And the albatrosses here have, over the past 10 years, been in decline. 219 00:20:02,660 --> 00:20:05,830 There are a number of possible reasons. 220 00:20:05,955 --> 00:20:07,749 While foraging at sea, 221 00:20:07,832 --> 00:20:11,961 albatross can get entangled and drowned by fishing gear. 222 00:20:13,797 --> 00:20:16,633 But Lucy is particularly alarmed 223 00:20:16,716 --> 00:20:19,886 by what the parents are bringing back for their chick. 224 00:20:20,178 --> 00:20:22,889 Albatrosses have the ability to cough up 225 00:20:22,972 --> 00:20:25,392 bits of food that they can't digest. 226 00:20:25,475 --> 00:20:28,478 And from that we can tell what they've been eating. 227 00:20:29,396 --> 00:20:33,733 A healthy albatross chick in its diet should really have things like squid. 228 00:20:33,817 --> 00:20:37,737 So we can find the squid beaks that come out of the pellet. 229 00:20:37,821 --> 00:20:41,533 And also things like fish so we can find fish bones as well. 230 00:20:43,868 --> 00:20:48,665 But these chicks are being fed something very different. 231 00:20:49,499 --> 00:20:54,712 We have some plastic that this poor chick has had to bring up. 232 00:20:56,005 --> 00:20:57,424 Plastic bag. 233 00:21:00,677 --> 00:21:03,888 Here we have some food packaging. Looks like rice. 234 00:21:04,722 --> 00:21:09,102 Luckily for this chick, he has managed to get this out of his stomach. 235 00:21:09,185 --> 00:21:12,439 So, fingers crossed he doesn't have any more plastic left in there 236 00:21:12,522 --> 00:21:13,773 before he fledges. 237 00:21:17,360 --> 00:21:21,197 For other chicks, plastic can be fatal. 238 00:21:23,199 --> 00:21:25,994 Unfortunately, there is a plastic toothpick 239 00:21:26,077 --> 00:21:28,288 that have actually gone through the stomach. 240 00:21:28,371 --> 00:21:32,917 Something just as small as that has actually has managed to kill the bird. 241 00:21:33,042 --> 00:21:34,711 It's really sad to see. 242 00:21:37,213 --> 00:21:42,552 Lucy collects and records what plastic she finds around the nests. 243 00:21:45,722 --> 00:21:50,935 These are items that were regurgitated just from last season. 244 00:21:51,060 --> 00:21:54,105 And that's gonna be a vast underestimation 245 00:21:54,230 --> 00:21:57,150 because that's just ones that we happen to find. 246 00:21:57,233 --> 00:22:01,070 There'll be many more that we never see being brought back. 247 00:22:04,407 --> 00:22:07,410 To find out where all this rubbish is coming from, 248 00:22:07,494 --> 00:22:13,249 Lucy and her team have attached GPS trackers to adult birds. 249 00:22:18,922 --> 00:22:21,716 It's showing where they're going to find food for themselves 250 00:22:21,799 --> 00:22:24,469 and to find food to bring back for their chicks. 251 00:22:25,470 --> 00:22:28,431 It really shows us that they could be picking up plastic 252 00:22:28,515 --> 00:22:31,017 from thousands of miles away. 253 00:22:31,809 --> 00:22:34,729 Plastics coming from either being dumped at sea 254 00:22:34,812 --> 00:22:37,524 or also from people's homes. 255 00:22:37,607 --> 00:22:41,486 Plastic gets into the rivers and then the rivers flow into the sea. 256 00:22:42,111 --> 00:22:45,823 So this isn't just a problem around these remote parts. 257 00:22:45,949 --> 00:22:47,992 This is happening worldwide. 258 00:22:48,117 --> 00:22:50,870 And it's our rubbish that's going into the oceans. 259 00:22:50,954 --> 00:22:53,540 It's our problem that we need to solve. 260 00:22:58,461 --> 00:23:00,421 In some parts of the ocean, 261 00:23:00,505 --> 00:23:05,802 it's estimated that there are now over one million pieces of plastic 262 00:23:05,885 --> 00:23:07,637 for every square mile. 263 00:23:09,013 --> 00:23:10,848 And we're only beginning to discover 264 00:23:10,974 --> 00:23:14,519 Just how seriously that affects marine life. 265 00:23:22,485 --> 00:23:25,321 On the east coast of the United States, 266 00:23:25,405 --> 00:23:30,702 researchers are investigating the mysterious deaths of young dolphins. 267 00:23:40,169 --> 00:23:43,756 The team is led by Dr Leslie Hart. 268 00:23:44,924 --> 00:23:47,260 It looks to be a young animal. 269 00:23:47,343 --> 00:23:49,178 Maybe a little bit over a year. 270 00:23:49,262 --> 00:23:52,724 So we're gonna try to find out more information on why this dolphin died. 271 00:24:01,441 --> 00:24:03,943 Looking at young dolphins... 272 00:24:04,027 --> 00:24:06,863 The very young dolphins, it's always heart-breaking. 273 00:24:14,912 --> 00:24:17,749 Leslie takes tissue samples. 274 00:24:18,458 --> 00:24:22,211 Their chemical analysis could provide crucial evidence. 275 00:24:23,296 --> 00:24:27,592 We are often shocked by the high levels of toxins 276 00:24:27,717 --> 00:24:29,552 that we detect in these animals. 277 00:24:31,137 --> 00:24:34,557 These young calves are dying for a number of reasons. 278 00:24:34,641 --> 00:24:38,811 But we suspect man-made toxins are playing a large role. 279 00:24:41,481 --> 00:24:44,400 And plastic could be part of the problem. 280 00:24:54,911 --> 00:24:56,537 Once in the ocean, 281 00:24:56,621 --> 00:24:59,832 plastic breaks down into tiny fragments. 282 00:25:00,750 --> 00:25:02,669 Micro plastics. 283 00:25:06,089 --> 00:25:10,259 Along with all the industrial chemicals that have drained into the ocean 284 00:25:10,343 --> 00:25:13,596 these form a potentially toxic soup. 285 00:25:20,103 --> 00:25:22,063 The really small organisms 286 00:25:22,146 --> 00:25:25,692 can mistake these tiny, tiny plastics as food. 287 00:25:25,775 --> 00:25:28,569 Then the larger organisms eat the plankton. 288 00:25:28,653 --> 00:25:31,322 Then the larger fish eat the smaller fish, 289 00:25:31,447 --> 00:25:32,949 and so on and so forth. 290 00:25:35,034 --> 00:25:38,371 Dolphins are at the top of this food chain 291 00:25:38,454 --> 00:25:42,166 and it's now thought that pollutants may be building up in their tissues 292 00:25:42,291 --> 00:25:48,131 to such a degree that a mother's contaminated milk could kill her calf 293 00:26:06,983 --> 00:26:11,529 Industrial pollution and the discarding of plastic waste 294 00:26:11,654 --> 00:26:16,159 must be tackled for the sake of all life in the ocean. 295 00:26:32,675 --> 00:26:36,471 Around the world, people are now devoting their lives 296 00:26:36,554 --> 00:26:39,891 to saving some of the most threatened sea creatures. 297 00:26:42,059 --> 00:26:44,771 As here in the Caribbean. 298 00:26:48,608 --> 00:26:51,611 Every year on just a few islands, 299 00:26:51,694 --> 00:26:54,447 a remarkable event takes place. 300 00:27:04,624 --> 00:27:07,293 As the sun sets, 301 00:27:07,376 --> 00:27:10,546 giant reptiles begin to emerge. 302 00:27:25,394 --> 00:27:29,148 This magnificent creature preparing... 303 00:27:31,400 --> 00:27:33,903 Preparing to lay her eggs 304 00:27:33,986 --> 00:27:36,989 is the largest of all turtles. 305 00:27:37,073 --> 00:27:38,491 A leatherback. 306 00:27:39,450 --> 00:27:43,412 They can grow up to half a ton in weight. 307 00:27:43,496 --> 00:27:47,500 And they have an ancestry that goes back a hundred million years 308 00:27:47,583 --> 00:27:49,669 to the age of the dinosaur. 309 00:27:50,962 --> 00:27:56,300 But in recent times their numbers have fallen catastrophically. 310 00:27:57,343 --> 00:28:01,681 Here, however, in the Caribbean there is hope. 311 00:28:06,519 --> 00:28:09,021 Leatherback turtles leave the sea 312 00:28:09,105 --> 00:28:12,441 in order to lay their eggs in the dry sand. 313 00:28:14,944 --> 00:28:20,116 But out of water, these huge creatures are easy targets for hunters. 314 00:28:23,953 --> 00:28:26,873 In a small fishing village in Trinidad, 315 00:28:26,956 --> 00:28:30,960 Len Peters has experienced this first hand. 316 00:28:32,295 --> 00:28:36,883 I grew up in a household where the presence of turtle meat was normal. 317 00:28:36,966 --> 00:28:38,843 The fridge was always full of it. 318 00:28:38,968 --> 00:28:42,138 Everybody... Everybody harvested turtles, including my parents. 319 00:28:43,139 --> 00:28:45,683 It's only when I became exposed to things 320 00:28:45,808 --> 00:28:47,643 that were being published about leatherbacks 321 00:28:47,727 --> 00:28:49,228 who were on the verge of extinction. 322 00:28:49,312 --> 00:28:50,938 And nobody cares. 323 00:28:51,022 --> 00:28:52,565 That piqued my interest. 324 00:28:53,649 --> 00:28:57,862 Len took the leatherback's future into his own hands. 325 00:28:59,822 --> 00:29:03,826 He began patrolling the beach at night to protect the turtles. 326 00:29:04,410 --> 00:29:06,162 A brave thing to do. 327 00:29:09,999 --> 00:29:12,919 We were met with tremendous resistance. 328 00:29:13,002 --> 00:29:14,837 People would pelt us at night. 329 00:29:14,921 --> 00:29:17,173 I have had persons insult me. 330 00:29:17,256 --> 00:29:18,883 I've had persons curse me. 331 00:29:19,008 --> 00:29:23,888 I've had persons physically try to wrestle me with a machete. 332 00:29:24,013 --> 00:29:26,724 So it was really a hostile time back then. 333 00:29:26,849 --> 00:29:29,644 If Len was going to save these turtles 334 00:29:29,727 --> 00:29:32,605 he needed to win over the whole community. 335 00:29:34,899 --> 00:29:39,320 We had to find a way to get the villagers to benefit 336 00:29:39,403 --> 00:29:41,530 from the presence of these animals. 337 00:29:44,784 --> 00:29:48,663 He began to encourage tourists to visit the beach 338 00:29:48,746 --> 00:29:51,791 and trained some villagers to be their guides. 339 00:29:56,087 --> 00:29:58,756 To help secure the turtle's future, 340 00:29:58,881 --> 00:30:02,051 he took the message to the next generation. 341 00:30:02,635 --> 00:30:06,806 Now what's... What's the largest size a leatherback can grow to? 342 00:30:07,223 --> 00:30:09,392 Uh, Shanie. 343 00:30:09,642 --> 00:30:11,602 - 2,000 pounds. - That's correct. 344 00:30:11,727 --> 00:30:15,606 Leatherbacks can grow to 2,000 pounds. 345 00:30:15,731 --> 00:30:17,316 Well, that's a big turtle. 346 00:30:17,984 --> 00:30:20,111 Len's hard work paid off 347 00:30:20,236 --> 00:30:22,613 And now, attitudes have changed. 348 00:30:26,575 --> 00:30:30,204 It took us a while to reach out to the villagers. 349 00:30:30,287 --> 00:30:32,832 But gradually we got them involved as well. 350 00:30:32,915 --> 00:30:36,002 We got some of the poachers who would be hunting the animals to 351 00:30:36,252 --> 00:30:38,087 be part of the conservation programme. 352 00:30:40,798 --> 00:30:43,384 As well as protecting the adult turtles, 353 00:30:43,467 --> 00:30:47,930 the team also collect any eggs that might be flooded at high tide. 354 00:30:51,100 --> 00:30:54,061 If the eggs are laid too close to the sea, 355 00:30:54,145 --> 00:30:56,856 we relocate the eggs and rebury them. 356 00:30:58,274 --> 00:31:00,985 Thanks to the efforts of this community, 357 00:31:01,110 --> 00:31:04,780 these turtles have had an extraordinary change in fortune. 358 00:31:07,033 --> 00:31:09,660 This is now thought to be one of the densest 359 00:31:09,785 --> 00:31:12,663 leatherback nesting beaches in the world. 360 00:31:16,709 --> 00:31:20,379 When we started at the height of the nesting season, 361 00:31:20,463 --> 00:31:24,300 the numbers will be 30-40 turtles a night. 362 00:31:24,383 --> 00:31:26,177 Now, it's over 500. 363 00:31:26,302 --> 00:31:29,722 So, we have seen an increase from 40 turtles 364 00:31:29,805 --> 00:31:32,892 to 500 turtles a night in just around 20 years. 365 00:31:36,687 --> 00:31:40,649 Precious new hatchlings are also given a helping hand. 366 00:31:44,320 --> 00:31:47,531 Any that emerge during the day are collected 367 00:31:47,656 --> 00:31:52,536 to be released safely back to the sea, away from hungry birds. 368 00:32:00,002 --> 00:32:04,840 This little leatherback will have to face a thousand hazards 369 00:32:04,924 --> 00:32:09,512 before it returns as an adult to this beach where it hatched. 370 00:32:10,387 --> 00:32:13,724 And those dangers will be greatly increased 371 00:32:13,849 --> 00:32:17,186 because of damage that we have done to the ocean. 372 00:32:19,188 --> 00:32:20,689 Good luck, little leatherback. 373 00:32:53,472 --> 00:32:55,933 Protecting breeding sites on beaches 374 00:32:56,058 --> 00:33:00,646 may improve the fortune of some marine animals, 375 00:33:00,729 --> 00:33:05,067 but safeguarding them while they roam the high seas is much more difficult. 376 00:33:10,281 --> 00:33:13,325 Out here, there is little protection. 377 00:33:22,585 --> 00:33:28,841 Every night, thousands of miles of fishing lines laden with hooks are set. 378 00:33:31,302 --> 00:33:34,763 There's enough, it's said, to wrap twice around the world. 379 00:33:39,935 --> 00:33:43,355 Nets large enough to engulf cathedrals 380 00:33:43,439 --> 00:33:46,817 trap hundreds of tons offish at a time. 381 00:33:49,612 --> 00:33:54,283 Long distance travellers such as sharks are particularly at risk. 382 00:34:00,831 --> 00:34:05,294 It's estimated that tens of millions are killed every year, 383 00:34:05,377 --> 00:34:10,382 including the biggest fish in the sea, the whale shark. 384 00:34:22,978 --> 00:34:26,774 Shark biologist Jonathan Green is concerned 385 00:34:26,857 --> 00:34:30,402 that time is running out for these extraordinary creatures. 386 00:34:31,654 --> 00:34:34,490 We know that they're being fished possibly at a massive rate. 387 00:34:34,990 --> 00:34:38,577 They may be taken by the thousands, possibly tens of thousands a year. 388 00:34:39,328 --> 00:34:41,080 If that is indeed true, 389 00:34:41,163 --> 00:34:44,833 we don't know how long they can withstand that kind of fishing pressure. 390 00:34:46,669 --> 00:34:49,713 To save them, Jonathan is trying to solve 391 00:34:49,838 --> 00:34:52,549 the mystery of where they give birth. 392 00:34:58,889 --> 00:35:03,435 And, for the first time, he has a clue as to where this might be. 393 00:35:11,026 --> 00:35:15,281 Pregnant whale sharks are thought to be travelling from across the Pacific Ocean 394 00:35:15,364 --> 00:35:18,200 to Darwin Island in the Galapagos. 395 00:35:27,251 --> 00:35:29,545 Jonathan is going to try and attach 396 00:35:29,628 --> 00:35:33,257 a multi-sensor camera tag to a pregnant female. 397 00:35:34,258 --> 00:35:35,718 Okay. We're good to go. 398 00:35:44,643 --> 00:35:47,938 These sharks only stay in the area for a few days. 399 00:35:48,939 --> 00:35:50,941 This may be his only chance. 400 00:36:03,746 --> 00:36:09,335 Jonathan has to attach the tag before the shark dives to dangerous depths. 401 00:36:29,313 --> 00:36:32,775 The tag will remain on the giant's fin for two days 402 00:36:32,858 --> 00:36:35,027 before it's automatically released. 403 00:36:37,821 --> 00:36:41,950 Once retrieved, it reveals some unusual behaviour. 404 00:36:44,703 --> 00:36:46,288 Oh, beautiful, beautiful. 405 00:36:48,957 --> 00:36:53,462 There's a silky rubbing at the in front. Next to her right. 406 00:36:53,879 --> 00:36:57,758 The silky sharks are brushing up against her rough skin, 407 00:36:57,841 --> 00:37:00,219 perhaps to scrape off parasites. 408 00:37:02,137 --> 00:37:07,101 These predatory sharks make the surface waters very unsafe places 409 00:37:07,184 --> 00:37:09,478 for young fish of any kind. 410 00:37:12,481 --> 00:37:14,817 There is a surprise in store. 411 00:37:16,568 --> 00:37:19,696 The tag's depth sensor reveals that she dived 412 00:37:19,822 --> 00:37:22,533 to a depth of 600 metres. 413 00:37:24,827 --> 00:37:28,372 But down there, it's too dark for the camera. 414 00:37:34,878 --> 00:37:38,257 The only way Jonathan can prove if they're giving birth 415 00:37:39,174 --> 00:37:41,051 is to go down and look. 416 00:38:05,576 --> 00:38:09,538 Out of the gloom, a shape materialises. 417 00:38:12,207 --> 00:38:14,376 Another massive whale shark. 418 00:38:16,378 --> 00:38:19,631 Oh, look at her. She's having a look at us. She's looking right at us. 419 00:38:24,970 --> 00:38:27,097 She is huge. 420 00:38:27,222 --> 00:38:29,725 And look at the belly. Absolutely massive. 421 00:38:31,059 --> 00:38:32,895 That's a large pregnant female. 422 00:38:33,896 --> 00:38:35,939 She's turning around. She's turning around. 423 00:38:42,279 --> 00:38:45,157 Goes to show we can follow them. We can follow them in the submarine. 424 00:38:49,244 --> 00:38:52,414 She leads them down into the darkness. 425 00:38:55,334 --> 00:38:59,505 Rover control. Passing 100 metres, descending. 426 00:39:02,090 --> 00:39:05,844 Heading down. I think she's accelerated slightly. 427 00:39:09,765 --> 00:39:11,600 She's too fast. 428 00:39:12,684 --> 00:39:16,813 And with the strong current running against them, the sub can't keep up. 429 00:39:21,777 --> 00:39:25,531 But, for the first time, Jonathan can see for himself 430 00:39:25,614 --> 00:39:27,533 exactly where she's headed. 431 00:39:30,285 --> 00:39:32,454 What specifically Darwin could provide 432 00:39:32,538 --> 00:39:37,501 is a safe refuge for those new-born pups where predators can't access. 433 00:39:39,336 --> 00:39:42,089 Perfect conditions for the formative years 434 00:39:42,172 --> 00:39:44,132 of these ocean-travelling giants. 435 00:39:52,307 --> 00:39:53,976 That was unbelievable. 436 00:39:55,686 --> 00:39:57,521 Dream of a lifetime. 437 00:40:00,357 --> 00:40:02,609 His discovery that pregnant whale sharks 438 00:40:02,693 --> 00:40:05,779 are visiting this very deep patch of the sea floor 439 00:40:05,862 --> 00:40:10,200 is strong evidence that this is indeed where the giants produce their young. 440 00:40:13,078 --> 00:40:16,623 If I can actually prove that they are giving birth in this area, 441 00:40:16,707 --> 00:40:18,875 then we'll have the information necessary 442 00:40:19,001 --> 00:40:21,044 to go to governments and actually say, 443 00:40:21,169 --> 00:40:24,464 "You must preserve those routes that they're migrating through." 444 00:40:24,548 --> 00:40:28,051 And then, and only then, can we really truly afford protection 445 00:40:28,176 --> 00:40:30,345 for this beautiful ocean traveller. 446 00:40:38,520 --> 00:40:40,772 Today, less than one percent 447 00:40:40,856 --> 00:40:43,692 of our international waters are protected. 448 00:40:46,695 --> 00:40:50,198 And the creation of marine reserves is vital 449 00:40:50,282 --> 00:40:54,411 if we're to safeguard the future of many ocean creatures. 450 00:41:00,542 --> 00:41:03,295 It will require international cooperation. 451 00:41:04,796 --> 00:41:06,798 But here, too, there is hope. 452 00:41:09,217 --> 00:41:11,470 We can turn things around. 453 00:41:12,220 --> 00:41:14,264 We've done so once before. 454 00:41:15,223 --> 00:41:19,144 For centuries, the sea-going nations of the world 455 00:41:19,227 --> 00:41:22,314 hunted the great whales until they were close to extinction. 456 00:41:23,231 --> 00:41:27,694 And then, in 1986, those nations got together 457 00:41:27,778 --> 00:41:31,823 and agreed to put a stop to commercial whaling. 458 00:41:35,744 --> 00:41:39,665 Today, although a few nations continue to hunt whales, 459 00:41:39,748 --> 00:41:42,626 some of the great whales are making a recovery. 460 00:41:51,343 --> 00:41:54,221 In the tropical seas surrounding Sri Lanka, 461 00:41:54,304 --> 00:41:57,933 there are stories of vast gatherings of whales. 462 00:42:02,270 --> 00:42:05,899 When the civil war ended in 2009, 463 00:42:05,982 --> 00:42:10,028 locals here were able once again to fish these waters. 464 00:42:12,948 --> 00:42:16,576 There were soon reports of assemblies of sperm whales, 465 00:42:16,660 --> 00:42:19,955 the likes of which had not been seen for centuries. 466 00:42:22,290 --> 00:42:26,378 Marine guide Daya was determined to get to the truth 467 00:42:26,461 --> 00:42:28,880 behind these fishermen's tales. 468 00:42:29,881 --> 00:42:32,217 The fishermen told me that there are lots of whales 469 00:42:32,300 --> 00:42:33,552 a little bit north from here. 470 00:42:34,511 --> 00:42:37,013 They didn't actually tell me a number, 471 00:42:37,139 --> 00:42:40,600 but in big numbers, not one or twos. 472 00:42:40,684 --> 00:42:42,728 Er, many. 473 00:42:47,399 --> 00:42:49,818 It took him three years, 474 00:42:49,901 --> 00:42:54,656 but eventually, he found evidence to support these rumours. 475 00:43:43,121 --> 00:43:46,541 We saw about 15 sperm whales go past us. 476 00:43:56,718 --> 00:43:58,887 Then, another four came past us. 477 00:44:02,390 --> 00:44:05,936 After about 40 then passed me, I started counting. 478 00:44:11,233 --> 00:44:13,735 Still, they kept coming, so I lost count. 479 00:44:16,238 --> 00:44:19,407 I estimated that we saw about 300 sperm whales. 480 00:44:27,249 --> 00:44:31,336 Sperm whales were once killed in vast numbers 481 00:44:31,461 --> 00:44:34,381 and it's thought that if the slaughter had continued, 482 00:44:34,464 --> 00:44:38,009 the species would be in danger of extermination. 483 00:44:41,429 --> 00:44:46,351 But now, here at least, they are being seen in huge numbers. 484 00:44:47,936 --> 00:44:51,940 I believe they come here to feed, mate, and raise their young. 485 00:44:52,023 --> 00:44:54,651 So, this must be a holiday spot for them, you know. 486 00:44:54,985 --> 00:44:58,446 At the moment, I don't know of any other place in the world 487 00:44:58,530 --> 00:45:01,366 that, er, sperm whales gather like this. 488 00:45:04,953 --> 00:45:08,707 Although some whale populations are still in decline, 489 00:45:08,790 --> 00:45:13,712 scenes like this prove that when sea-going nations come together, 490 00:45:13,795 --> 00:45:16,965 they can achieve astonishing results. 491 00:45:25,181 --> 00:45:30,896 But today, the oceans face threats on a truly global scale. 492 00:45:36,902 --> 00:45:38,987 The Great Barrier Reef 493 00:45:41,489 --> 00:45:45,076 The largest coral reef system in the world. 494 00:45:47,871 --> 00:45:53,376 Here, we filmed stories which reveal Just how smart fish can be. 495 00:45:59,341 --> 00:46:02,177 This ingenious tuskfish, for example, 496 00:46:02,260 --> 00:46:06,848 used a favourite coral anvil to smash open shellfish. 497 00:46:09,225 --> 00:46:12,854 This astonishing behaviour has been closely studied 498 00:46:12,938 --> 00:46:15,523 by local scientist Alex Vail. 499 00:46:17,359 --> 00:46:19,903 We're calling Percy "Percy the Persistent" 500 00:46:21,279 --> 00:46:24,616 because he took, like, an hour to open the first shell. 501 00:46:30,288 --> 00:46:32,791 He must have hit it well over 50 times, 502 00:46:32,874 --> 00:46:35,877 but he just kept on going and finally got it open. 503 00:46:45,720 --> 00:46:48,890 Alex grew up on the Great Barrier Reef 504 00:46:48,974 --> 00:46:51,893 on one of its more remote islands, Lizard. 505 00:46:54,396 --> 00:46:56,731 He knows the reef intimately. 506 00:47:02,278 --> 00:47:06,199 But, in 2016, while he was filming for Blue Planet II, 507 00:47:06,282 --> 00:47:08,910 Alex witnessed a catastrophe. 508 00:47:10,954 --> 00:47:13,957 When we started filming, everything was pretty much fine. 509 00:47:14,082 --> 00:47:16,251 All of the corals were basically healthy. 510 00:47:18,420 --> 00:47:21,840 But in the last few weeks, everything changed. 511 00:47:22,924 --> 00:47:25,760 I have never seen anything like this before. 512 00:47:29,097 --> 00:47:31,349 A combination of a warming ocean 513 00:47:31,433 --> 00:47:35,186 and an unpredictable weather event called El Niño 514 00:47:35,270 --> 00:47:38,023 raised sea temperatures to record levels. 515 00:47:43,278 --> 00:47:46,656 And this had a disastrous effect on the corals. 516 00:47:48,283 --> 00:47:52,662 The heat causes reef-building corals to lose their nourishing algae, 517 00:47:53,705 --> 00:47:56,332 exposing their white skeletons. 518 00:48:01,463 --> 00:48:05,717 When temperatures remain high, bleached corals die off 519 00:48:08,720 --> 00:48:11,806 The bleaching this year has been the worst in history 520 00:48:11,890 --> 00:48:13,391 for the Great Barrier Reef. 521 00:48:13,475 --> 00:48:16,019 About 90 percent of the branching corals 522 00:48:16,144 --> 00:48:18,563 on the reef out here at Lizard Island are dead. 523 00:48:21,649 --> 00:48:24,444 It also has disastrous consequences 524 00:48:24,527 --> 00:48:26,821 for the other creatures that live here. 525 00:48:30,492 --> 00:48:33,328 Percy swimming around out there. 526 00:48:33,411 --> 00:48:36,498 The really sad thing is that his castle's starting to bleach. 527 00:48:37,832 --> 00:48:41,211 If we lose our coral, there's a chance we're going to lose our tuskfish. 528 00:48:43,254 --> 00:48:47,008 It's incredibly sad to see areas that you've dived on 529 00:48:47,092 --> 00:48:50,428 since you were a little kid just turn to rubble. 530 00:48:53,723 --> 00:48:55,934 I cried in my mask, when I saw, 531 00:48:56,017 --> 00:48:58,228 you know, some of the devastation from this bleaching. 532 00:49:06,528 --> 00:49:08,446 In the last three years, 533 00:49:08,530 --> 00:49:11,574 over two-thirds of the world's coral reefs 534 00:49:11,699 --> 00:49:15,537 are thought to have suffered from rises in ocean temperatures. 535 00:49:28,883 --> 00:49:31,386 This is not the only challenge they face. 536 00:49:34,139 --> 00:49:36,683 Research is revealing how the fundamental 537 00:49:36,766 --> 00:49:39,144 chemistry of the ocean is changing. 538 00:49:42,814 --> 00:49:46,151 Professor Chris Langdon shows me what this might mean 539 00:49:46,234 --> 00:49:51,322 for the future of our seas by pouring dilute acid over shells. 540 00:49:56,578 --> 00:50:00,331 And how much more acidic is this than the present ocean? 541 00:50:00,999 --> 00:50:04,627 This is more concentrated than the pH of the ocean 542 00:50:05,253 --> 00:50:08,673 but it accelerates the process so we can see something visually. 543 00:50:09,257 --> 00:50:12,635 So, what's happening is, these shells, they're made out of calcium carbonate, 544 00:50:13,428 --> 00:50:15,013 and the acid is dissolving them. 545 00:50:15,638 --> 00:50:19,601 And coral reefs are made out of the same material as these shells here. 546 00:50:20,518 --> 00:50:24,689 But surely this is not happening in the ocean now. Right now? 547 00:50:24,772 --> 00:50:28,401 What we're seeing here is more dramatic than what's happening in the ocean. 548 00:50:28,484 --> 00:50:33,364 But the shells and the reefs are really truly dissolving. 549 00:50:33,448 --> 00:50:36,701 Coral reefs could be gone by the end of this century. 550 00:50:40,038 --> 00:50:43,666 And the cause of this? Carbon dioxide. 551 00:50:45,501 --> 00:50:49,130 Dissolved in the sea water, it forms carbonic acid. 552 00:50:50,131 --> 00:50:52,717 The more carbon dioxide in the atmosphere, 553 00:50:52,800 --> 00:50:55,220 the more acidic the ocean becomes. 554 00:50:57,513 --> 00:51:00,475 Evidence points to the burning of fossil fuels 555 00:51:00,558 --> 00:51:05,313 as the primary cause for these increasing levels of carbon dioxide. 556 00:51:07,232 --> 00:51:09,901 And this is man-made beyond question. 557 00:51:09,984 --> 00:51:11,236 Beyond question. 558 00:51:15,531 --> 00:51:18,743 But Chris believes all is not lost. 559 00:51:20,328 --> 00:51:24,457 All we have to do, and I say all, is reduce our CO2 emissions. 560 00:51:24,540 --> 00:51:28,836 We can switch to renewable fuels, wind and solar, 561 00:51:28,920 --> 00:51:30,964 instead of natural fossil fuels. 562 00:51:31,047 --> 00:51:32,840 And so, none of this has to 563 00:51:33,758 --> 00:51:36,261 - develop to the worst case. - And that could fix it? 564 00:51:36,344 --> 00:51:41,182 Yeah, absolutely. So, this future does not have to play out. It's up to us. 565 00:51:52,527 --> 00:51:56,281 As the climate changes, the seas warm. 566 00:51:56,406 --> 00:51:59,409 Our oceans are being seriously affected. 567 00:52:02,078 --> 00:52:06,582 And this is nowhere more apparent than at the poles. 568 00:52:15,925 --> 00:52:17,593 Antarctica. 569 00:52:21,723 --> 00:52:26,394 For the Blue Planet II team, this was their most ambitious expedition. 570 00:52:29,230 --> 00:52:33,234 For the first time in history, a manned submersible 571 00:52:33,318 --> 00:52:36,946 will try to dive to a depth of 1,000 metres 572 00:52:37,071 --> 00:52:39,574 and reach the Antarctic seabed. 573 00:52:40,992 --> 00:52:43,911 A true journey into the unknown. 574 00:52:49,584 --> 00:52:51,919 (RADIO CHATTER 575 00:53:01,262 --> 00:53:04,640 Control rover. Passing 40 metres. Over. 576 00:53:10,938 --> 00:53:14,025 Leading the team on this historic dive 577 00:53:14,108 --> 00:53:16,444 is deep sea scientist John Copley. 578 00:53:24,619 --> 00:53:28,289 We get our first glimpse of this landscape. 579 00:53:31,125 --> 00:53:34,962 And the carpet of life around us is astounding. 580 00:53:35,713 --> 00:53:37,048 It's beautiful. 581 00:53:46,391 --> 00:53:51,312 Diving in a submersible gives John an entirely new understanding 582 00:53:51,396 --> 00:53:54,190 of how this rich ecosystem works. 583 00:53:55,983 --> 00:53:59,195 But it also offers him a unique opportunity 584 00:53:59,320 --> 00:54:02,323 to investigate how the ocean here is changing. 585 00:54:03,658 --> 00:54:05,701 While we're observing the marine life down there, 586 00:54:05,827 --> 00:54:08,204 the subs are also recording what the environment is like, 587 00:54:08,329 --> 00:54:10,748 so we're getting measurements of temperature, of salinity. 588 00:54:10,832 --> 00:54:13,209 It's hopefully gonna enable us to understand the changes 589 00:54:13,334 --> 00:54:15,545 that are happening in this vital part of our planet. 590 00:54:18,714 --> 00:54:21,426 To get a fuller picture, John also lowers 591 00:54:21,509 --> 00:54:23,845 a deep sea temperature probe. 592 00:54:29,392 --> 00:54:33,229 His data is contributing to an international attempt 593 00:54:33,354 --> 00:54:37,108 to chart the rise in both sea and air temperatures. 594 00:54:40,403 --> 00:54:42,697 What shocks me about what all the data show 595 00:54:42,780 --> 00:54:45,408 is how fast things are changing here. 596 00:54:48,202 --> 00:54:51,080 We're headed into uncharted territory. 597 00:54:58,588 --> 00:55:00,715 To truly comprehend 598 00:55:00,798 --> 00:55:03,092 the effect of the temperature increases here, 599 00:55:03,217 --> 00:55:05,386 John takes to the skies. 600 00:55:06,596 --> 00:55:10,057 From here, he can record the number and size 601 00:55:10,141 --> 00:55:14,812 of the icebergs being produced as the ice shelfs melt and break apart. 602 00:55:17,482 --> 00:55:21,068 The bergs we're seeing all around us give you some idea 603 00:55:21,152 --> 00:55:25,740 of how huge this process is that's taking place on the Antarctic. 604 00:55:27,074 --> 00:55:30,953 As the floating shelves break up, they allow water, 605 00:55:31,078 --> 00:55:34,665 which has been locked up on land as ice for thousands of years, 606 00:55:34,749 --> 00:55:36,626 to empty into the sea. 607 00:55:38,586 --> 00:55:41,923 And this is predicted to push up sea levels. 608 00:55:46,594 --> 00:55:49,931 If the ice shelves break up, then that opens the flood gates. 609 00:55:50,806 --> 00:55:53,017 Ice on land flows faster into the sea 610 00:55:53,100 --> 00:55:54,810 and that's what pushes up the sea levels. 611 00:55:56,812 --> 00:56:00,775 So, what's happening here right now affects all of us. 612 00:56:15,790 --> 00:56:19,961 Already, cities like Miami here are under threat. 613 00:56:20,836 --> 00:56:24,131 Scientists predict that by the end of the century, 614 00:56:24,215 --> 00:56:28,177 the sea levels could have risen by a metre or even two. 615 00:56:28,844 --> 00:56:33,641 Were that to happen, parts of this city would certainly be submerged. 616 00:56:38,521 --> 00:56:43,276 Around the world, hundreds of millions of people live near the coast, 617 00:56:43,359 --> 00:56:48,072 and as sea levels rise, their lives will be seriously affected. 618 00:57:01,877 --> 00:57:06,090 It's now clear that our actions are having a significant impact 619 00:57:06,173 --> 00:57:08,009 on the world's oceans. 620 00:57:12,888 --> 00:57:16,475 During the four years it took to make this series, 621 00:57:16,559 --> 00:57:19,770 we've witnessed many of these changes first-hand. 622 00:57:29,030 --> 00:57:32,241 But we've also worked alongside men and women 623 00:57:32,366 --> 00:57:36,245 dedicating their lives to safeguarding the ocean's future. 624 00:57:44,045 --> 00:57:47,423 The oceans provide us with oxygen, 625 00:57:47,548 --> 00:57:49,550 they regulate temperature, 626 00:57:49,634 --> 00:57:52,803 they provide us with food and energy supplies. 627 00:57:53,471 --> 00:57:58,559 And it's unthinkable to have a world without a healthy ocean. 628 00:58:02,563 --> 00:58:05,441 I still think we have the capability 629 00:58:05,566 --> 00:58:08,736 to change the manner in which we're wasting resources, 630 00:58:08,819 --> 00:58:10,905 in which we're poisoning our oceans, 631 00:58:10,988 --> 00:58:14,742 and we can look to a future with healthy oceans. 632 00:58:17,328 --> 00:58:21,999 When I look forward, I believe that if what we are doing 633 00:58:22,083 --> 00:58:24,627 can be duplicated just a little bit. 634 00:58:24,752 --> 00:58:27,755 These animals will have a chance of surviving. 635 00:58:29,340 --> 00:58:33,928 It comes down, I think, to us each taking responsibility 636 00:58:34,095 --> 00:58:36,764 for the personal choices that we make in our everyday lives. 637 00:58:36,847 --> 00:58:39,809 That's all any of us can be expected to do. 638 00:58:39,934 --> 00:58:42,603 And it is those everyday choices that add up. 639 00:58:58,661 --> 00:59:01,706 We are at a unique stage in our history. 640 00:59:02,665 --> 00:59:06,752 Never before have we had such an awareness 641 00:59:06,836 --> 00:59:08,879 of what we are doing to the planet. 642 00:59:09,964 --> 00:59:15,219 And never before have we had the power to do something about that. 643 00:59:17,388 --> 00:59:21,392 Surely, we have a responsibility to care for our blue planet. 644 00:59:22,560 --> 00:59:25,479 The future of humanity, 645 00:59:25,563 --> 00:59:28,941 and indeed all life on Earth, 646 00:59:29,024 --> 00:59:31,402 now depends on us.