1
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A family of scimitar-toothed cats.

2
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For millennia they've thrived here
in the icy north.

3
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But right now, they're starving.

4
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The prey the cats hunt
is becoming scarce in these valleys…

5
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because the climate is warming,

6
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forcing grazing animals
to find new feeding grounds.

7
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Today, they might be in luck.

8
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A mammoth herd, trying a new route south.

9
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Taking on such powerful creatures
is a huge risk.

10
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But they don't have a choice.

11
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It's the end of the Ice Age.

12
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As the planet heats up,
every habitat on Earth is changing.

13
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As ice retreats,
water returns to the landscape

14
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and forest animals thrive.

15
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But the rulers of the Ice Age

16
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are facing the end of the world they know…

17
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and struggling to survive.

18
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The cats make their move.

19
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The biggest danger?

20
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A huge male.

21
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Unpredictable and powerful.

22
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She's injured
but these cats won't give up.

23
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The warming climate
has changed migration routes

24
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in this part of the world.

25
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On the coast, its effects are spectacular.

26
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Mineral-rich ice is falling
in huge quantities,

27
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filling the shallow sea with nutrients.

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This family of sea cows have come here
to feed on a forest of lush kelp

29
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fed by the meltwater.

30
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These Ice Age giants
are relatives of manatees…

31
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but the size of a whale.

32
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Kelp is their favorite food.

33
00:05:31,748 --> 00:05:35,586
But it only grows
in shallow coastal waters…

34
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so feeding here can be risky.

35
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When the tide goes out,
strandings are common.

36
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Out of the water, he's too heavy to move.

37
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And today,
this beach is not a good place to be.

38
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A short-faced bear.

39
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500 pounds heavier than a polar bear

40
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and even more deadly.

41
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One of the biggest predators
to walk the Earth since the dinosaurs.

42
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He's picked up a scent.

43
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He's never seen anything like it.

44
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But it smells like food.

45
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It's all very confusing.

46
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A short-faced bear
could tear most animals to shreds.

47
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Luckily for the sea cow,

48
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he's protected by
tough skin an inch thick.

49
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The bear's attack is just an irritation.

50
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Or maybe, a welcome back scratch.

51
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The tide's coming back in.

52
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Fast.

53
00:08:41,063 --> 00:08:44,566
For the bear,
the chance of a meal is slipping away.

54
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Time to rejoin his family.

55
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He's got plenty of eating to catch up on.

56
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Here on the coast, the Big Melt means
more nutritious kelp for sea cows…

57
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while for many Ice Age giants

58
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life is getting harder.

59
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For animals living thousands of miles
to the south,

60
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the warming climate is turning
this scrubland into a dangerous place.

61
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At night, a Columbian mammoth
is safe enough feeding here.

62
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But once the sun comes up…

63
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even this giant is in danger.

64
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A lake of tar.

65
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It seeps to the surface
from deep within the Earth's crust.

66
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When cold, it's hard and safe to walk on.

67
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But when the temperature
reaches 64 degrees…

68
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it turns into a sticky death trap.

69
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Today it's claimed a new victim.

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North American saber-toothed cats
are powerful hunters.

71
00:12:43,430 --> 00:12:47,518
But they won't say no
to scavenging an easy meal.

72
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The sun is low,
so the tar is still solid underfoot.

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Dire wolves.

74
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The saber-toothed cats' deadly rivals.

75
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Pack hunters with a bone-crushing bite.

76
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The pack will kill the cubs
if they get the chance.

77
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Sabertooths and dire wolves
are an even match.

78
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But the tar has changed everything.

79
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The dire wolves use their powerful
sense of smell to find a safe path.

80
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With her cubs in mortal danger…

81
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she finds the strength to break free.

82
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The pack are powerless to help.

83
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Tar pits caused the deaths
of thousands of Ice Age creatures.

84
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This family has been lucky.

85
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As the temperature rises around the world,

86
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life is also changing dramatically
on Ice Age grasslands.

87
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These reindeer are managing.

88
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But survival is getting much harder
for Megaloceros…

89
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a giant Ice Age deer.

90
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He needs open ground to thrive.

91
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But as water returns to the landscape,

92
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forests are taking over once again.

93
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He's the proud owner
of the biggest antlers of all time.

94
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Twelve feet across.

95
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In breeding season
they help attract a mate.

96
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At this time of the year, though,
they're a burden.

97
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Cave hyenas.

98
00:18:20,184 --> 00:18:25,022
Ferocious predators
twice the size of a wolf.

99
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They've hunted these giants
for thousands of years.

100
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Megaloceros are fast.

101
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Once they get going they can reach
over 50 miles per hour.

102
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With a head start
he can outsprint the hyenas.

103
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But they don't give up.

104
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They have an age-old strategy.

105
00:19:07,523 --> 00:19:10,734
If they can stay just close enough
to keep him running…

106
00:19:11,276 --> 00:19:13,779
and never let him catch his breath…

107
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they might run him down.

108
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Maybe sooner than they think.

109
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There's only one way out.

110
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Safe…

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for now.

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As the ice sheets melt,

113
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the Earth's atmosphere
gets wetter and wetter.

114
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Here in the tropics,

115
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forests are expanding
even faster than in the north.

116
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And they're full of strange animals…

117
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like this tenrec.

118
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They love to eat insects…

119
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and birds' eggs.

120
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But this one is out of his league.

121
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It is after all
the biggest egg of all time.

122
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And it belongs to
the biggest bird of all time.

123
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An elephant bird.

124
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Their brightly colored neck wattles
help attract a mate.

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This giant is about to become a father.

126
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But something is wrong.

127
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His chick is taking its time.

128
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They're running late.

129
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Elephant birds
synchronize their egg laying

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so the chicks hatch at the same time.

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The flock heads off together
on a road trip.

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When you weigh one ton,
flying isn't an option.

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No one likes to be left behind.

134
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But this chick just won't be hurried.

135
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The others have already left,

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heading for their
summer home in the wetlands.

137
00:23:19,983 --> 00:23:23,070
But she's still a bit wobbly on her feet.

138
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For the next nine months
he'll be her sole provider and protector.

139
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They need to catch up with the convoy.

140
00:24:09,658 --> 00:24:13,078
Elephant birds travel together
for good reason.

141
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The forest is a dangerous place.

142
00:24:27,885 --> 00:24:30,470
Stragglers are a prime target.

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Giant fossa.

144
00:24:56,079 --> 00:25:00,459
An ambush predator, fast and agile.

145
00:25:09,343 --> 00:25:12,179
This is no time for a snack.

146
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The convoy has arrived at its destination.

147
00:26:10,946 --> 00:26:12,865
Rain has returned here…

148
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creating these wetlands…

149
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with plenty of food and drink for all.

150
00:26:30,340 --> 00:26:32,676
But what about the stragglers?

151
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Even the very last chick to hatch
has made it.

152
00:26:56,867 --> 00:27:02,206
As wetlands expand,
their numbers are growing every year.

153
00:27:05,375 --> 00:27:10,881
The Big Melt is the start of a golden age
for elephant birds.

154
00:27:13,133 --> 00:27:18,972
But for the giant stag,
the world is closing in.

155
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In a forest,
12-foot antlers are a liability.

156
00:27:44,540 --> 00:27:49,211
Downstream, the hyenas have found
a place to cross.

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Trapped.

158
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A miraculous escape.

159
00:29:33,148 --> 00:29:36,735
Shedding his antlers saved him.

160
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A new set will grow
for the next breeding season.

161
00:29:49,206 --> 00:29:55,546
But the time for his kind
and the hyenas is running out.

162
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The saber-toothed cats have been
tracking the mammoth herd for two days.

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Their patience has paid off.

164
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The male,

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injured during the cats' first attack,
has fallen behind.

166
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He's vulnerable.

167
00:30:54,271 --> 00:30:58,358
In the cat world, her kind are unique.

168
00:30:59,943 --> 00:31:02,654
She has the power of a lion…

169
00:31:05,365 --> 00:31:08,243
and the agility of a leopard.

170
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The cats will survive another winter.

171
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The mammoth herd too.

172
00:32:10,013 --> 00:32:12,015
But their world is changing.

173
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A new predator born of the Ice Age

174
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is spreading to every corner
of the planet.

175
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And that story is still unfolding.

176
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Giant mammals ruled the Ice Age.

177
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But almost all of them died out
during the Big Melt.

178
00:32:59,813 --> 00:33:02,274
It's wild and super weird to think

179
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that all the big animals
that used to exist completely disappeared.

180
00:33:08,197 --> 00:33:09,781
What happened to them?

181
00:33:11,450 --> 00:33:12,534
And why?

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00:33:19,583 --> 00:33:22,836
One surprising place has some answers.

183
00:33:23,754 --> 00:33:24,796
Los Angeles.

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00:33:26,256 --> 00:33:31,678
If you came to LA
and saw the massive network of freeways,

185
00:33:31,762 --> 00:33:35,974
it would never occur to you
this had one of the richest records

186
00:33:36,058 --> 00:33:38,352
of the Ice Age anywhere on the planet.

187
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Like the African savanna on steroids.

188
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Most people don't move to LA
to be paleontologists.

189
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But some of us do.

190
00:33:48,946 --> 00:33:50,447
That's why I'm here.

191
00:33:51,657 --> 00:33:55,285
Emily's here
because of an extraordinary place.

192
00:33:55,369 --> 00:34:01,291
An ancient pool of tar
called the La Brea Tar Pits.

193
00:34:02,543 --> 00:34:07,047
La Brea Tar pits is the richest
Ice Age fossil site in the world.

194
00:34:08,090 --> 00:34:10,926
We've found close to five million fossils

195
00:34:12,469 --> 00:34:16,681
and we are still excavating
new ones almost every single day.

196
00:34:18,934 --> 00:34:21,018
These pools of tar

197
00:34:21,103 --> 00:34:25,482
have acted as traps
that have caught and preserved

198
00:34:25,565 --> 00:34:29,360
anything living that has walked into them

199
00:34:30,362 --> 00:34:34,949
and built up the most
incredible record of Ice Age life.

200
00:34:43,917 --> 00:34:48,755
You have this unbelievably
rich fossil record at La Brea.

201
00:34:48,839 --> 00:34:50,090
The number of bones

202
00:34:50,174 --> 00:34:53,552
that have come out of this site
is extraordinary.

203
00:34:54,344 --> 00:34:58,348
We have probably close to
3,000 saber-toothed cats.

204
00:34:58,849 --> 00:35:00,517
5,000 dire wolves.

205
00:35:01,310 --> 00:35:04,730
This is like an Aladdin's cave of fossils.

206
00:35:06,231 --> 00:35:10,652
What's odd is that
the fossil record suddenly stops…

207
00:35:11,945 --> 00:35:15,532
as if the animals just
vanished off the face of the Earth.

208
00:35:17,826 --> 00:35:20,579
We are able to radiocarbon date the bone

209
00:35:20,662 --> 00:35:24,041
and pinpoint exactly
when they disappeared.

210
00:35:25,209 --> 00:35:28,962
What was surprising
was that almost all of these species

211
00:35:29,046 --> 00:35:31,673
disappeared exactly
the same moment in time.

212
00:35:31,757 --> 00:35:37,179
They all hit this wall at 13,000 years ago
and they never show up again.

213
00:35:38,555 --> 00:35:43,185
Those vast landscapes
teeming with herds of enormous

214
00:35:43,268 --> 00:35:46,480
Ice Age creatures and
they're suddenly just gone.

215
00:35:47,606 --> 00:35:50,859
The disappearance of
these animals makes us wonder,

216
00:35:50,943 --> 00:35:53,654
"Why did this happen so suddenly?"

217
00:35:53,737 --> 00:35:56,156
One reason was that the climate changed

218
00:35:56,240 --> 00:35:58,784
too fast at the end of the Ice Age.

219
00:35:59,493 --> 00:36:04,998
California warmed ten degrees
in just a few thousand years.

220
00:36:05,082 --> 00:36:07,084
Half of the trees disappeared.

221
00:36:07,167 --> 00:36:09,962
Droughts lasted for decades at a time.

222
00:36:10,838 --> 00:36:14,174
It's possible that the animals

223
00:36:14,258 --> 00:36:18,720
were just simply not able to adapt
fast enough to this changing climate.

224
00:36:21,849 --> 00:36:26,061
But the work at La Brea
shows something else was going on.

225
00:36:27,354 --> 00:36:32,067
The team started looking at
core samples from a nearby lake

226
00:36:32,150 --> 00:36:36,446
to understand what was going on
with the environment at this time.

227
00:36:36,530 --> 00:36:41,952
And what's really surprising is
there was a huge increase in charcoal.

228
00:36:43,871 --> 00:36:46,623
A new species had arrived.

229
00:36:47,624 --> 00:36:51,420
And with it a devastating new force.

230
00:36:56,300 --> 00:36:59,011
Fire is the most powerful tool
people have ever invented.

231
00:36:59,720 --> 00:37:05,642
We set fires to cook, to see at night,
to clear land for hunting.

232
00:37:06,476 --> 00:37:13,150
The first people to arrive in this area
were living in a complete tinderbox.

233
00:37:14,151 --> 00:37:16,570
People brought in the ignition source.

234
00:37:18,238 --> 00:37:20,282
In tens of thousands of years

235
00:37:20,365 --> 00:37:24,203
there had never been any level
of fire activity anywhere close to this.

236
00:37:25,787 --> 00:37:27,456
It's like a bomb going off.

237
00:37:27,956 --> 00:37:30,167
That can completely decimate
the environment

238
00:37:30,250 --> 00:37:34,046
and puts huge amounts of pressure
on the animals that were living there.

239
00:37:35,631 --> 00:37:40,636
Whether the fires were
intentional or accidental isn't known,

240
00:37:41,178 --> 00:37:43,847
but they destroyed animal habitats.

241
00:37:44,765 --> 00:37:48,060
And combined with the hunting skills
of our ancestors

242
00:37:49,019 --> 00:37:51,063
it was the perfect storm.

243
00:37:52,022 --> 00:37:53,065
Across the planet,

244
00:37:53,148 --> 00:37:57,194
this combination of climate change
and human activity

245
00:37:57,945 --> 00:38:01,323
killed off almost all the Ice Age giants,

246
00:38:02,032 --> 00:38:04,868
leading to the world we know today.