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[static crackling]
[static crackling]

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00:00:13,306 --> 00:00:15,808
[indistinct muffled radio chatter]

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00:00:19,729 --> 00:00:21,939
[David Attenborough] <i>Just 50 years ago,</i>

4
00:00:22,523 --> 00:00:25,443
<i>we finally ventured to the moon.</i>

5
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<i>For the very first time,</i>
<i>we look back at our own planet.</i>

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<i>Since then, the human population</i>
<i>has more than doubled.</i>

7
00:01:03,314 --> 00:01:07,860
<i>This series will celebrate</i>
<i>the natural wonders that remain,</i>

8
00:01:08,694 --> 00:01:11,405
<i>and reveal what we must preserve</i>

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<i>to ensure people and nature thrive.</i>

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<i>When human beings</i>
<i>built their first settlements</i>

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<i>some 10,000 years ago,</i>

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<i>the world around them,</i>

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<i>on the land and in the sea,</i>

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<i>was full of life.</i>

15
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<i>For generations, this stable Eden</i>
<i>nurtured our growing civilizations.</i>

16
00:02:16,053 --> 00:02:20,308
<i>But now, in the space</i>
<i>of just one human lifetime,</i>

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<i>all that has changed.</i>

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<i>In the last 50 years,</i>

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<i>wildlife populations have, on average,</i>
<i>declined by 60 percent.</i>

20
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<i>For the first time in human history,</i>

21
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<i>the stability of nature</i>
<i>can no longer be taken for granted.</i>

22
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[ice cracking]

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<i>But the natural world is resilient.</i>

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<i>Great riches still remain.</i>

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<i>And with our help, the planet can recover.</i>

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<i>Never has it been more important</i>
<i>to understand how the natural world works,</i>

27
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<i>and how to help it.</i>

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[birds calling]

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[waves crashing]

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<i>Wildlife still flourishes</i>
<i>in astonishing numbers</i>

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<i>in a few precious places.</i>

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<i>Along the Peruvian coast of South America,</i>

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<i>seabirds congregate</i>
<i>in colonies millions strong.</i>

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<i>They come here to breed.</i>

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[birds calling]

36
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<i>Every morning,</i>
<i>the birds leave their colonies</i>

37
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<i>to fish in one of the richest seas</i>
<i>on Earth.</i>

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<i>It is an astonishing daily migration</i>

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<i>of five million birds.</i>

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<i>The huge flocks of cormorants and boobies</i>
<i>are all seeking one thing:</i>

41
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<i>anchovies.</i>

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[water rushing]

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<i>The boobies carpet-bomb the shoals.</i>

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<i>More and more birds</i>
<i>join the feeding frenzy.</i>

45
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[water splashing]

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[classical music score plays]

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<i>All in this immense assembly are here</i>

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<i>because a powerful oceanic current,</i>
<i>the Humboldt,</i>

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<i>sweeps up from the Antarctic,</i>

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<i>bringing with it rich nutrients</i>
<i>from the ocean's depths.</i>

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<i>90 percent of the life in the oceans</i>

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<i>is found in the shallow seas</i>
<i>close to the coast.</i>

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<i>Away from the land,</i>

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<i>the seas, for the most part,</i>
<i>are a blue desert.</i>

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<i>But even these distant waters</i>
<i>may be enriched</i>

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<i>by a most unexpected connection</i>
<i>to the land.</i>

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<i>Some deserts,</i>

58
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<i>often hundreds of kilometers</i>
<i>from the ocean,</i>

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<i>provide the raw materials for life.</i>

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[wind blowing]

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<i>Every year, winds sweep up</i>
<i>two billion tons of dust into the sky.</i>

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<i>At least a quarter of it</i>
<i>eventually falls on the sea,</i>

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<i>providing nutrients</i>
<i>needed by the microscopic organisms</i>

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<i>that are the foundations of ocean life.</i>

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[water splashing]

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<i>Dolphins explore the vast, open ocean</i>

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<i>in search of the riches</i>
<i>that distant deserts may have nourished.</i>

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[dolphins spouting]

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<i>A shoal of mackerel</i>
<i>has discovered a swarm of krill...</i>

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<i>the small crustaceans</i>

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<i>that feed on the ocean's</i>
<i>floating microscopic plants.</i>

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<i>But the mackerel themselves</i>
<i>are food for the dolphins.</i>

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[dolphins whistling]

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[water rushing]

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<i>They drive the mackerel</i>
<i>towards the surface,</i>

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<i>and into the range of birds.</i>

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<i>Shearwaters.</i>

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<i>The wings that normally propel the birds</i>
<i>through the air</i>

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<i>now drive them six meters down</i>
<i>through the water.</i>

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[water rushing]

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<i>Whilst the birds</i>
<i>pick off the top of the shoal...</i>

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<i>the dolphins attack the underside.</i>

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[water rushing]

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[dolphins whistling]

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[water rushing]

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<i>After 20 minutes of feasting,</i>

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<i>the predators</i>
<i>from both the sea and the air</i>

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00:10:01,935 --> 00:10:03,312
<i>have had their fill.</i>

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<i>The stability of life on our planet</i>

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<i>relies on such connections</i>
<i>between different habitats.</i>

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00:10:31,632 --> 00:10:34,760
<i>Water evaporating</i>
<i>from the surface of the sea</i>

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00:10:35,260 --> 00:10:38,180
<i>condenses to form great clouds.</i>

93
00:10:40,891 --> 00:10:46,730
<i>And these eventually</i>
<i>release the fresh water as rain.</i>

94
00:10:50,943 --> 00:10:56,573
<i>But these life-giving rains</i>
<i>are not evenly spread over the land.</i>

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<i>This vast salt pan in Africa</i>

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<i>is all that remains of an ancient lake.</i>

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<i>It's totally waterless and oven-hot.</i>

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<i>Few places on the land</i>
<i>are more hostile to life.</i>

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<i>A few tracks cross it, made by animals</i>
<i>searching unsuccessfully for water.</i>

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[snorting]

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<i>But very occasionally,</i>
<i>this whole landscape is transformed.</i>

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[thunder rumbling]

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[thunderclap]

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<i>A huge deluge drenches the salt pan.</i>

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00:12:26,830 --> 00:12:28,582
[rain pouring]

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[thunder rumbling]

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<i>Triggered by some unknown signal,</i>

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<i>flocks of lesser flamingos</i>
<i>arrive from thousands of kilometers away.</i>

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<i>The algae that the flamingos feed on</i>

110
00:13:02,616 --> 00:13:05,911
<i>have lain dormant as spores in the dust.</i>

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00:13:10,833 --> 00:13:12,543
<i>But most importantly,</i>

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00:13:13,043 --> 00:13:15,546
<i>the birds are here to breed.</i>

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<i>Perfect conditions might occur</i>
<i>only once in a decade.</i>

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[flamingos squawking]

115
00:13:29,059 --> 00:13:32,145
<i>The birds nest on an island</i>
<i>far from the shore.</i>

116
00:13:32,896 --> 00:13:34,815
[mud splashing]

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<i>They build mounds of mud</i>
<i>that raise up their eggs</i>

118
00:13:38,151 --> 00:13:43,073
<i>and so keep them just marginally cooler</i>
<i>than they would be at ground level.</i>

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00:13:43,156 --> 00:13:44,783
[flamingos chattering]

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00:13:47,286 --> 00:13:50,247
<i>The water surrounding the island</i>
<i>is so salty</i>

121
00:13:50,330 --> 00:13:52,833
<i>that predators do not venture into it.</i>

122
00:13:53,917 --> 00:13:55,878
<i>So the nests are safe.</i>

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00:13:55,961 --> 00:13:57,462
[squawking]

124
00:14:00,340 --> 00:14:05,220
<i>Thirty days later,</i>
<i>thousands of chicks start to hatch.</i>

125
00:14:18,692 --> 00:14:22,613
<i>But there is no shelter</i>
<i>from the scorching sun.</i>

126
00:14:25,782 --> 00:14:29,202
<i>The water that once surrounded</i>
<i>their island, protecting them,</i>

127
00:14:29,536 --> 00:14:31,288
<i>has now dried up altogether.</i>

128
00:14:36,043 --> 00:14:38,629
[cheeping]

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00:14:38,712 --> 00:14:43,842
<i>The last to hatch</i>
<i>step out into a desperately harsh world.</i>

130
00:14:46,511 --> 00:14:48,597
-[chicks cheeping]
-[squawking]

131
00:14:55,479 --> 00:14:56,563
[squawking]

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00:14:57,439 --> 00:15:02,611
<i>Somehow or other, the growing chicks</i>
<i>must find fresh water to drink.</i>

133
00:15:03,528 --> 00:15:05,197
-[cheeping]
-[squawking]

134
00:15:07,157 --> 00:15:12,454
<i>They cannot yet fly, so they must walk,</i>
<i>guided by some of the adults.</i>

135
00:15:26,802 --> 00:15:30,055
<i>They may have to trek for 50 kilometers.</i>

136
00:15:55,288 --> 00:15:56,999
[frenzied cheeping and squawking]

137
00:16:01,253 --> 00:16:04,006
<i>Some... cannot keep up.</i>

138
00:16:09,636 --> 00:16:12,931
<i>The salt has solidified around their legs.</i>

139
00:16:13,765 --> 00:16:14,683
[cheeps]

140
00:16:44,921 --> 00:16:46,715
-[squawking]
-[splashing]

141
00:16:49,342 --> 00:16:52,137
<i>Most of the chicks,</i>
<i>in spite of everything,</i>

142
00:16:52,471 --> 00:16:54,306
<i>and having walked for days,</i>

143
00:16:54,389 --> 00:16:56,767
<i>eventually reach fresh water.</i>

144
00:17:03,231 --> 00:17:07,486
[frenzied squawking]

145
00:17:17,496 --> 00:17:19,581
<i>It is the end of a long journey...</i>

146
00:17:21,500 --> 00:17:26,338
<i>but only the first of the trials</i>
<i>that will be imposed on these flamingos</i>

147
00:17:26,505 --> 00:17:29,091
<i>by the irregularity of the rains.</i>

148
00:17:33,637 --> 00:17:36,139
-[rainfall]
-[snorting]

149
00:17:39,351 --> 00:17:42,479
<i>If rainfall is more predictable</i>
<i>and certain,</i>

150
00:17:42,562 --> 00:17:45,232
<i>then life can flourish more richly,</i>

151
00:17:46,358 --> 00:17:49,611
<i>both in numbers and variety.</i>

152
00:17:53,865 --> 00:17:59,496
<i>The Serengeti plains in East Africa</i>
<i>support over a million wildebeest.</i>

153
00:17:59,871 --> 00:18:02,040
[grunting]

154
00:18:02,499 --> 00:18:05,335
<i>The herds follow the seasonal rains,</i>

155
00:18:05,627 --> 00:18:09,464
<i>grazing on the newly-sprouting grass</i>
<i>that comes in their wake.</i>

156
00:18:09,840 --> 00:18:12,008
[grunting continues]

157
00:18:20,225 --> 00:18:22,769
<i>Each year, within a three-week period,</i>

158
00:18:23,061 --> 00:18:27,816
<i>the females give birth</i>
<i>to over a quarter of a million calves.</i>

159
00:18:35,031 --> 00:18:36,867
[bleating]

160
00:18:36,950 --> 00:18:39,786
<i>This youngster is just a few days old.</i>

161
00:18:40,912 --> 00:18:45,167
<i>Playing strengthens its legs</i>
<i>for the long journey that lies ahead.</i>

162
00:18:55,802 --> 00:18:57,804
[grunting]

163
00:19:16,740 --> 00:19:19,326
<i>The calf must stay close to its mother.</i>

164
00:19:19,868 --> 00:19:22,245
<i>Without her milk, it would starve.</i>

165
00:19:22,329 --> 00:19:24,623
-[snorting]
-[grunting]

166
00:19:26,458 --> 00:19:29,002
<i>And the herds are always traveling,</i>

167
00:19:30,128 --> 00:19:33,215
<i>following the rains</i>
<i>as they drift across the plains</i>

168
00:19:33,924 --> 00:19:35,842
<i>in order to find fresh grazing.</i>

169
00:19:39,888 --> 00:19:43,308
<i>Eventually, they reach woodlands.</i>

170
00:19:43,725 --> 00:19:46,853
[birds chirping]

171
00:19:46,937 --> 00:19:48,271
[grunting]

172
00:20:02,202 --> 00:20:03,703
<i>Hunting dogs.</i>

173
00:20:08,208 --> 00:20:11,211
<i>Wildebeest calves are a favorite prey.</i>

174
00:20:15,590 --> 00:20:17,425
<i>And the dogs are hungry.</i>

175
00:20:32,107 --> 00:20:36,528
<i>The calf must stay with its mother,</i>
<i>protected within the herd.</i>

176
00:21:07,726 --> 00:21:09,269
[wildebeest snorting]

177
00:21:19,696 --> 00:21:22,073
<i>The dogs have incredible stamina...</i>

178
00:21:26,036 --> 00:21:28,747
<i>but the calf is defended by the herd.</i>

179
00:21:37,547 --> 00:21:39,674
<i>They need the calf on its own.</i>

180
00:21:40,884 --> 00:21:42,093
[snorting]

181
00:21:42,177 --> 00:21:44,804
[hyenas panting]

182
00:21:58,318 --> 00:22:02,030
<i>The mother blocks the dogs,</i>
<i>shielding her calf.</i>

183
00:22:09,704 --> 00:22:11,664
<i>It makes a run for safety.</i>

184
00:22:22,675 --> 00:22:25,804
<i>And it just manages</i>
<i>to get back to the herd.</i>

185
00:22:52,539 --> 00:22:58,461
<i>The future of this whole migration</i>
<i>depends on the regularity of the rains,</i>

186
00:22:59,421 --> 00:23:04,175
<i>but also on the continued existence</i>
<i>of the great open grasslands</i>

187
00:23:04,342 --> 00:23:07,887
<i>across which the herds</i>
<i>make their immense journeys.</i>

188
00:23:11,057 --> 00:23:13,226
-[insects chittering]
-[birds calling]

189
00:23:15,645 --> 00:23:21,651
<i>In places where rains fall abundantly</i>
<i>throughout the year, forests grow,</i>

190
00:23:22,944 --> 00:23:25,113
<i>and in the warmth of the tropics,</i>

191
00:23:25,196 --> 00:23:28,616
<i>they support</i>
<i>an unparalleled richness of life.</i>

192
00:23:28,700 --> 00:23:31,995
[overlapping animal vocalizations]

193
00:23:32,078 --> 00:23:35,248
<i>Half of all the species</i>
<i>of land-living animals</i>

194
00:23:35,331 --> 00:23:37,709
<i>live in these stable worlds.</i>

195
00:23:39,586 --> 00:23:41,296
[bird whistling]

196
00:23:41,463 --> 00:23:44,757
<i>The sheer diversity is breathtaking.</i>

197
00:23:50,722 --> 00:23:52,682
<i>We still have not catalogued</i>

198
00:23:52,765 --> 00:23:56,186
<i>all the species that live</i>
<i>in the tropical forests.</i>

199
00:24:10,742 --> 00:24:16,664
<i>The relationships between them all</i>
<i>are multitudinous and complex.</i>

200
00:24:20,752 --> 00:24:22,212
[wings buzzing]

201
00:24:22,295 --> 00:24:26,382
<i>Plants often depend on animals</i>
<i>to pollinate their flowers.</i>

202
00:24:30,053 --> 00:24:31,971
<i>And these intimate connections</i>

203
00:24:32,055 --> 00:24:35,725
<i>are just as important</i>
<i>as the great global ones.</i>

204
00:24:35,808 --> 00:24:37,477
[buzzing]

205
00:24:45,485 --> 00:24:47,320
<i>These are traps.</i>

206
00:24:48,613 --> 00:24:50,782
<i>Flowers shaped like buckets,</i>

207
00:24:51,449 --> 00:24:52,825
<i>produced by an orchid.</i>

208
00:24:58,540 --> 00:24:59,832
[buzzing]

209
00:25:02,168 --> 00:25:07,298
<i>Each red bucket is filled</i>
<i>with an oily liquid that drips from above.</i>

210
00:25:12,971 --> 00:25:18,893
<i>Male orchid bees need a rich perfume</i>
<i>with which to impress their females,</i>

211
00:25:20,395 --> 00:25:22,605
<i>and the orchids provide it.</i>

212
00:25:25,984 --> 00:25:29,028
<i>But the bucket is slippery,</i>

213
00:25:32,031 --> 00:25:35,577
<i>and the liquid</i>
<i>into which the bee has fallen is sticky.</i>

214
00:25:39,497 --> 00:25:41,040
<i>The only way to get out</i>

215
00:25:42,458 --> 00:25:44,210
<i>is through a narrow tunnel.</i>

216
00:25:47,672 --> 00:25:51,050
<i>As it emerges, the bee is gripped tight.</i>

217
00:25:53,720 --> 00:25:56,222
<i>And that gives enough time for the plant</i>

218
00:25:56,973 --> 00:26:00,226
<i>to glue pollen sacs on the bee's back.</i>

219
00:26:03,771 --> 00:26:08,192
<i>So the orchid has its pollen</i>
<i>taken to another plant...</i>

220
00:26:10,653 --> 00:26:13,197
<i>and the bee is rewarded with a perfume,</i>

221
00:26:13,406 --> 00:26:16,159
<i>with which, when it recovers its strength,</i>

222
00:26:16,367 --> 00:26:18,244
<i>it can woo a female.</i>

223
00:26:22,874 --> 00:26:24,417
[water crashing]

224
00:26:25,668 --> 00:26:29,213
<i>There are no pronounced seasons</i>
<i>in a rainforest.</i>

225
00:26:32,717 --> 00:26:37,055
<i>It produces food in one form or another</i>
<i>the year round.</i>

226
00:26:41,184 --> 00:26:44,395
<i>It's so rich</i>
<i>that the females of some birds</i>

227
00:26:44,479 --> 00:26:47,899
<i>are able to raise their young</i>
<i>entirely by themselves,</i>

228
00:26:48,232 --> 00:26:52,820
<i>and that allows the males to spend</i>
<i>their whole time attracting females...</i>

229
00:26:53,529 --> 00:26:54,364
[cheeps]

230
00:26:54,447 --> 00:26:55,865
<i>...as manakins do.</i>

231
00:26:58,201 --> 00:27:00,495
<i>There are over 50 different species,</i>

232
00:27:00,578 --> 00:27:03,998
<i>each with its own</i>
<i>highly elaborate dance routine.</i>

233
00:27:06,084 --> 00:27:07,001
[cheeps]

234
00:27:11,714 --> 00:27:13,424
<i>The golden-collared manakin</i>

235
00:27:13,800 --> 00:27:16,302
<i>starts by clearing his dance floor.</i>

236
00:27:20,390 --> 00:27:21,224
[cheeps]

237
00:27:25,061 --> 00:27:28,231
<i>A female arrives</i>
<i>and he starts his routine,</i>

238
00:27:28,314 --> 00:27:30,608
<i>rocketing from one perch to another.</i>

239
00:27:30,692 --> 00:27:31,609
[fluttering]

240
00:27:32,777 --> 00:27:33,695
[cheeping]

241
00:27:35,154 --> 00:27:38,116
<i>She checks out every detail.</i>

242
00:27:47,291 --> 00:27:50,920
<i>Finally, he performs his signature move.</i>

243
00:27:51,754 --> 00:27:52,880
[tweets]

244
00:27:52,964 --> 00:27:54,340
<i>The back-flip...</i>

245
00:27:54,424 --> 00:27:55,258
[calls]

246
00:27:58,344 --> 00:27:59,554
<i>...with twist.</i>

247
00:28:03,182 --> 00:28:04,016
[calls]

248
00:28:04,100 --> 00:28:05,017
<i>Perfection.</i>

249
00:28:06,477 --> 00:28:08,312
-[cheeps]
-[whir of wings]

250
00:28:09,147 --> 00:28:13,067
<i>The red-capped manakin</i>
<i>has a very different act.</i>

251
00:28:14,277 --> 00:28:15,194
[cheeps]

252
00:28:16,404 --> 00:28:18,740
<i>It's a kind of slither.</i>

253
00:28:18,823 --> 00:28:19,699
[cheeps]

254
00:28:19,782 --> 00:28:21,701
[feet pattering]

255
00:28:22,285 --> 00:28:23,536
[cheeps]

256
00:28:26,289 --> 00:28:27,123
[cheeps]

257
00:28:28,916 --> 00:28:30,668
<i>With wing snaps.</i>

258
00:28:30,752 --> 00:28:31,586
[snap]

259
00:28:31,669 --> 00:28:32,795
[calls]

260
00:28:35,631 --> 00:28:37,341
-[cheep]
-[snap]

261
00:28:37,425 --> 00:28:38,885
[wings snapping]

262
00:28:43,347 --> 00:28:45,725
<i>But it doesn't seem to be working.</i>

263
00:28:48,269 --> 00:28:49,103
[cheeps]
[tweets]

264
00:28:59,947 --> 00:29:01,282
[wings snapping]

265
00:29:02,867 --> 00:29:04,368
<i>She's seen enough.</i>

266
00:29:07,830 --> 00:29:09,207
[chirruping]

267
00:29:09,290 --> 00:29:13,711
<i>The most complex routine</i>
<i>is that developed by the blue manakin.</i>

268
00:29:15,505 --> 00:29:20,009
<i>The lead male</i>
<i>is supported by three junior dancers.</i>

269
00:29:20,468 --> 00:29:22,553
[calling]

270
00:29:22,637 --> 00:29:25,348
<i>They practice together almost every day.</i>

271
00:29:28,184 --> 00:29:29,560
<i>During rehearsals,</i>

272
00:29:29,644 --> 00:29:33,689
<i>a young male in juvenile plumage</i>
<i>stands in for the female.</i>

273
00:29:33,856 --> 00:29:35,525
[twittering]

274
00:29:38,778 --> 00:29:41,739
<i>The dance</i>
<i>has to be perfectly synchronized.</i>

275
00:29:42,782 --> 00:29:44,575
[high-pitched tweets]

276
00:29:47,203 --> 00:29:48,079
[chirrups]

277
00:29:48,246 --> 00:29:49,914
<i>With the lead male happy...</i>

278
00:29:53,251 --> 00:29:56,462
<i>they're ready to present their dance</i>
<i>to a female.</i>

279
00:29:58,673 --> 00:30:00,591
-[calling]
-[fluttering]

280
00:30:09,141 --> 00:30:13,563
<i>In a carousel of movements,</i>
<i>each male takes his turn at the front.</i>

281
00:30:14,438 --> 00:30:15,982
-[calling]
-[fluttering]

282
00:30:35,001 --> 00:30:37,837
<i>The lead male performs the final move.</i>

283
00:30:37,920 --> 00:30:39,463
[high-pitched tweets]

284
00:30:42,300 --> 00:30:43,551
<i>Have they done enough?</i>

285
00:30:45,553 --> 00:30:46,762
<i>What's her decision?</i>

286
00:30:46,846 --> 00:30:49,056
[chirruping]

287
00:30:53,394 --> 00:30:54,312
<i>It's...</i>

288
00:30:54,770 --> 00:30:55,855
<i>a yes!</i>

289
00:31:00,401 --> 00:31:02,028
<i>A great team effort.</i>

290
00:31:02,361 --> 00:31:04,989
[chirruping]

291
00:31:07,617 --> 00:31:12,538
<i>Tropical forests cover</i>
<i>only seven percent of the planet's lands.</i>

292
00:31:14,457 --> 00:31:18,127
<i>Away from the tropics,</i>
<i>where the weather is seasonal and cooler,</i>

293
00:31:18,544 --> 00:31:19,795
<i>they're very different.</i>

294
00:31:23,424 --> 00:31:27,011
<i>The greatest of all is the boreal forest</i>

295
00:31:27,678 --> 00:31:31,390
<i>that extends right across North America</i>
<i>and Eurasia.</i>

296
00:31:38,481 --> 00:31:42,026
<i>It cannot grow</i>
<i>during the frigid grip of winter.</i>

297
00:31:46,322 --> 00:31:48,991
<i>The forests are a crucial refuge</i>

298
00:31:49,450 --> 00:31:53,829
<i>for the relatively few species</i>
<i>that are able to survive here.</i>

299
00:32:01,796 --> 00:32:03,214
[wind howls]
<i>As winter approaches,</i>

300
00:32:05,174 --> 00:32:08,636
<i>caribou grazing on the open tundra</i>
<i>to the north</i>

301
00:32:09,095 --> 00:32:13,474
<i>head south to the forest</i>
<i>to seek food and shelter.</i>

302
00:32:25,069 --> 00:32:29,949
<i>Out here, temperatures may fall</i>
<i>below minus 40 degrees centigrade.</i>

303
00:32:38,499 --> 00:32:42,878
<i>The forest will give some protection</i>
<i>from the worst of the weather.</i>

304
00:33:08,904 --> 00:33:13,284
<i>But now the caribou</i>
<i>are not traveling alone.</i>

305
00:33:22,877 --> 00:33:23,753
<i>Wolves.</i>

306
00:33:24,920 --> 00:33:27,298
<i>They live in the forest year-round.</i>

307
00:33:32,803 --> 00:33:36,640
<i>And in the winter,</i>
<i>they specialize in hunting caribou.</i>

308
00:33:51,530 --> 00:33:53,949
<i>They must find the freshest tracks.</i>

309
00:34:05,544 --> 00:34:08,923
<i>They move fast by avoiding the deep snow,</i>

310
00:34:09,590 --> 00:34:13,177
<i>sticking to the hard-packed trails</i>
<i>made by the caribou.</i>

311
00:34:18,516 --> 00:34:21,185
<i>This wolf has found fresh scent.</i>

312
00:34:31,529 --> 00:34:33,364
<i>The caribou must be close.</i>

313
00:34:43,791 --> 00:34:48,462
<i>The herd chooses to stop to rest</i>
<i>on a frozen lake.</i>

314
00:34:50,798 --> 00:34:54,260
<i>Out in the open, they will be able to spot</i>
<i>approaching danger.</i>

315
00:34:54,343 --> 00:34:57,138
[faint grunting]

316
00:34:58,139 --> 00:35:01,308
<i>And sure enough, the wolves catch up.</i>

317
00:35:08,357 --> 00:35:10,609
[caribou bleating]

318
00:35:15,781 --> 00:35:17,992
<i>They start to test the caribou,</i>

319
00:35:18,909 --> 00:35:20,619
<i>probing for any weakness.</i>

320
00:35:21,537 --> 00:35:23,289
[rapid bleating]

321
00:35:33,674 --> 00:35:35,134
<i>Out on the open lake,</i>

322
00:35:36,093 --> 00:35:38,637
<i>the caribou can outrun the wolves...</i>

323
00:35:45,436 --> 00:35:48,397
<i>so the wolves drive them back</i>
<i>into the forest.</i>

324
00:35:56,614 --> 00:36:01,577
<i>Here, in the deep snow,</i>
<i>progress is much harder and slower.</i>

325
00:36:05,998 --> 00:36:07,541
[bleating]

326
00:36:10,711 --> 00:36:14,924
<i>And, hidden by the trees,</i>
<i>the wolves can get closer.</i>

327
00:36:20,721 --> 00:36:22,389
<i>The hunt is on.</i>

328
00:36:23,474 --> 00:36:25,017
[bleating]

329
00:36:26,393 --> 00:36:29,021
[snorting]

330
00:36:32,524 --> 00:36:34,902
[bleating]

331
00:36:34,985 --> 00:36:39,031
<i>The pack must decide</i>
<i>which particular caribou to target</i>

332
00:36:40,908 --> 00:36:42,451
<i>and which trail to take.</i>

333
00:36:49,708 --> 00:36:51,293
<i>As the caribou scatter,</i>

334
00:36:53,504 --> 00:36:56,257
<i>the leading wolf takes a wrong turn.</i>

335
00:37:00,010 --> 00:37:04,807
<i>It's a crucial mistake,</i>
<i>and the wolves abandon the chase.</i>

336
00:37:14,108 --> 00:37:18,445
<i>With the coming of spring,</i>
<i>the caribou will head north once more,</i>

337
00:37:18,696 --> 00:37:21,657
<i>leaving the wolves and the forest behind.</i>

338
00:37:24,660 --> 00:37:29,790
<i>They will travel 600 kilometers,</i>
<i>crossing mountains to reach the tundra,</i>

339
00:37:30,082 --> 00:37:32,918
<i>where the spring grass</i>
<i>will be sprouting again,</i>

340
00:37:33,460 --> 00:37:34,878
<i>and they can give birth.</i>

341
00:37:37,423 --> 00:37:42,261
<i>But these migrations</i>
<i>are a shadow of what they once were.</i>

342
00:37:44,388 --> 00:37:48,350
<i>The herd has lost</i>
<i>nearly 70 percent of its numbers</i>

343
00:37:48,434 --> 00:37:50,311
<i>in the last 20 years.</i>

344
00:37:53,355 --> 00:37:58,193
<i>Their world and all of our planet</i>
<i>is now changing fast.</i>

345
00:38:05,075 --> 00:38:07,703
<i>At the furthest polar extremes</i>

346
00:38:08,329 --> 00:38:13,584
<i>lie the frozen wildernesses</i>
<i>of Antarctica and the Arctic.</i>

347
00:38:18,130 --> 00:38:21,216
<i>Though they may seem remote</i>
<i>to many of us,</i>

348
00:38:22,009 --> 00:38:27,431
<i>the stability of these icy wastes</i>
<i>is crucial to all life on the planet.</i>

349
00:38:33,228 --> 00:38:39,068
<i>But in just 70 years,</i>
<i>things have changed at a frightening pace.</i>

350
00:38:41,612 --> 00:38:46,492
<i>The polar regions are warming faster</i>
<i>than any other part of the planet.</i>

351
00:38:53,665 --> 00:38:57,753
<i>The Arctic in the north is a frozen ocean,</i>

352
00:38:59,713 --> 00:39:03,509
<i>and the sea ice,</i>
<i>on which all life here depends,</i>

353
00:39:04,551 --> 00:39:05,677
<i>is disappearing.</i>

354
00:39:13,227 --> 00:39:15,687
[panting]

355
00:39:21,568 --> 00:39:22,820
<i>Polar bears</i>

356
00:39:23,404 --> 00:39:27,449
<i>specialize in hunting seals</i>
<i>out on the frozen ocean.</i>

357
00:39:33,163 --> 00:39:38,085
<i>But that world is now, literally,</i>
<i>melting beneath their feet.</i>

358
00:39:42,381 --> 00:39:44,842
<i>The sea ice breaks up every year,</i>

359
00:39:45,384 --> 00:39:47,428
<i>but now this is happening earlier,</i>

360
00:39:47,761 --> 00:39:51,390
<i>and the bears' limited hunting season</i>
<i>is getting shorter.</i>

361
00:39:53,892 --> 00:39:57,146
<i>This is already having a profound impact.</i>

362
00:40:01,066 --> 00:40:02,568
[gentle snorting]

363
00:40:09,575 --> 00:40:11,994
<i>Cubs are growing up underweight,</i>
<i>which reduces their chances of survival.</i>

364
00:40:19,126 --> 00:40:20,627
[snuffling]

365
00:40:35,142 --> 00:40:37,686
<i>Within the lifetime of these cubs,</i>

366
00:40:37,769 --> 00:40:42,774
<i>the Arctic in summer</i>
<i>could be largely free of sea ice.</i>

367
00:40:45,611 --> 00:40:47,029
[gentle snorting]

368
00:40:58,874 --> 00:41:02,294
<i>It's not just the sea ice</i>
<i>that is vanishing.</i>

369
00:41:03,921 --> 00:41:08,217
<i>The ice that lies on land</i>
<i>is also changing fast.</i>

370
00:41:12,846 --> 00:41:14,890
<i>This is Greenland,</i>

371
00:41:15,724 --> 00:41:20,896
<i>a vast expanse of ice</i>
<i>one-fifth the size of the United States.</i>

372
00:41:28,111 --> 00:41:31,657
<i>This glacial ice,</i>
<i>together with the sea ice,</i>

373
00:41:31,949 --> 00:41:37,120
<i>protects our planet by reflecting</i>
<i>solar radiation away from the surface</i>

374
00:41:37,329 --> 00:41:40,332
<i>and so preventing the Earth</i>
<i>from overheating.</i>
<i>But the Arctic is warming dramatically.</i>

375
00:41:56,473 --> 00:42:00,936
<i>The leading edge of the Store Glacier</i>
<i>may appear to be motionless,</i>

376
00:42:02,145 --> 00:42:06,149
<i>but glaciers can move</i>
<i>at up to 45 meters a day.</i>

377
00:42:06,275 --> 00:42:08,235
[ice rumbling]

378
00:42:13,115 --> 00:42:18,078
<i>Where this one meets the sea,</i>
<i>it towers 100 meters above the water,</i>

379
00:42:19,580 --> 00:42:22,874
<i>and continues downward</i>
<i>for another 400 meters</i>

380
00:42:22,958 --> 00:42:24,376
<i>beneath the surface.</i>

381
00:42:29,548 --> 00:42:31,425
[ice cracking]

382
00:42:40,642 --> 00:42:42,185
[waves rushing]

383
00:43:07,919 --> 00:43:12,883
<i>Over the last 20 years,</i>
<i>Greenland has been losing ice.</i>

384
00:43:19,181 --> 00:43:22,809
<i>And the rate of loss is accelerating.</i>

385
00:43:25,228 --> 00:43:26,772
[ice rumbling]

386
00:43:31,985 --> 00:43:33,820
[crashing]

387
00:43:38,116 --> 00:43:41,495
<i>These massive icefalls</i>
<i>from the top of the glacier</i>

388
00:43:41,870 --> 00:43:43,413
<i>are just the beginnings</i>

389
00:43:43,872 --> 00:43:45,832
<i>of a far greater event.</i>

390
00:43:47,501 --> 00:43:49,711
[icefalls crashing in distance]

391
00:43:50,629 --> 00:43:55,258
<i>A stretch of the front face of the glacier</i>
<i>over a kilometer long</i>

392
00:43:55,342 --> 00:43:57,386
<i>is starting to break away.</i>

393
00:43:57,469 --> 00:43:59,096
[ice rumbling]

394
00:44:01,932 --> 00:44:03,350
[ice crashing]

395
00:44:08,563 --> 00:44:11,233
<i>From 400 meters beneath the surface,</i>

396
00:44:11,775 --> 00:44:14,695
<i>the hidden ice is surging upwards.</i>

397
00:44:17,239 --> 00:44:18,865
[waves rushing]

398
00:44:30,919 --> 00:44:32,671
[crashing]

399
00:44:32,754 --> 00:44:36,633
<i>The breakaway of an iceberg</i>
<i>the size of a skyscraper</i>

400
00:44:37,676 --> 00:44:40,721
<i>generates a colossal tidal wave.</i>

401
00:44:42,305 --> 00:44:44,057
[wave rushing]

402
00:44:56,695 --> 00:44:58,947
-[crashing]
-[rumbling]

403
00:45:15,714 --> 00:45:17,716
[classical music score plays]

404
00:45:56,713 --> 00:46:02,928
<i>Within 20 minutes,</i>
<i>75 million tons of ice break free.</i>

405
00:46:10,143 --> 00:46:13,814
<i>Glaciers have always released ice</i>
<i>into the ocean,</i>

406
00:46:14,981 --> 00:46:18,235
<i>but now this is happening</i>
<i>nearly twice as fast</i>

407
00:46:18,318 --> 00:46:20,403
<i>as it did ten years ago.</i>

408
00:46:23,615 --> 00:46:29,162
<i>Around the world, ice is now feeding</i>
<i>vast amounts of fresh water into the sea,</i>

409
00:46:29,871 --> 00:46:35,669
<i>raising sea levels, changing salinity,</i>
<i>and disrupting ocean currents.</i>

410
00:46:39,047 --> 00:46:44,386
<i>Without the Humboldt Current,</i>
<i>the coast of Peru would fall silent.</i>

411
00:46:45,846 --> 00:46:48,932
<i>The seabird spectacle would be no more.</i>

412
00:47:00,569 --> 00:47:05,532
<i>All across our planet,</i>
<i>crucial connections are being disrupted.</i>

413
00:47:09,452 --> 00:47:14,708
<i>The stability that we</i>
<i>and all life relies upon is being lost.</i>

414
00:47:18,086 --> 00:47:21,131
<i>What we do in the next 20 years</i>

415
00:47:22,465 --> 00:47:26,678
<i>will determine the future</i>
<i>for all life on Earth.</i>

416
00:47:35,478 --> 00:47:40,609
<i>The rest of this series will explore</i>
<i>the planet's most important habitats,</i>

417
00:47:42,110 --> 00:47:45,822
<i>and celebrate the life they still support.</i>

418
00:47:53,413 --> 00:47:56,833
<i>We will reveal what must be preserved</i>

419
00:47:57,042 --> 00:48:03,715
<i>if we are to ensure a future</i>
<i>where humans and nature can thrive.</i>

420
00:48:13,850 --> 00:48:19,648
<i>Please visit ourplanet.com to find out</i>
<i>how our planet can thrive again.</i>

421
00:48:22,984 --> 00:48:24,736
[Ellie Goulding:
"In This Together"]

422
00:48:24,819 --> 00:48:29,282
<i>♪ I can hear the whole world</i>
<i>Singing together ♪</i>

423
00:48:31,576 --> 00:48:37,791
<i>♪ I can hear the whole world say</i>
<i>"It's now or never" ♪</i>

424
00:48:40,335 --> 00:48:44,756
<i>♪ 'Cause it's not too late</i>
<i>If we change our ways ♪</i>

425
00:48:44,839 --> 00:48:48,510
<i>♪ And connect the dots to our problems ♪</i>

426
00:48:48,593 --> 00:48:54,641
<i>♪ I can hear the whole world say</i>
<i>"We're in this together" ♪</i>

427
00:48:54,724 --> 00:48:56,726
<i>♪ We're in this together ♪</i>