1
00:00:02,040 --> 00:00:07,240
Speaker 1: Welcome to Brainstuff from how Stuff Works, Hey, brain Stuff,

2
00:00:07,280 --> 00:00:10,520
Speaker 1: Lauren Vogel bomb here the history of life is chronicled

3
00:00:10,520 --> 00:00:14,120
Speaker 1: in our fossil record. Scientists use skeletons, trackways, and other

4
00:00:14,200 --> 00:00:17,640
Speaker 1: tangible calling cards to learn new things about prehistoric organisms.

5
00:00:17,960 --> 00:00:22,240
Speaker 1: But how do they study prehistoric climates? Unlike dinosaurs or mastodon's,

6
00:00:22,400 --> 00:00:25,239
Speaker 1: the climate has no bones to leave behind, no footprints

7
00:00:25,239 --> 00:00:28,800
Speaker 1: to track. Telltale indicators of past weather conditions can still

8
00:00:28,840 --> 00:00:31,480
Speaker 1: be found, though, if you know where to look for them.

9
00:00:31,680 --> 00:00:35,240
Speaker 1: One important line of evidence lies inside the world glacial ice.

10
00:00:35,680 --> 00:00:40,120
Speaker 1: Glaciers form where snow is steadily accumulating but not melting. Slowly,

11
00:00:40,280 --> 00:00:43,519
Speaker 1: the weight of new layers deforms the snow crystals below them.

12
00:00:43,560 --> 00:00:46,880
Speaker 1: The compression fuses old buried snowflakes together until they become

13
00:00:46,880 --> 00:00:50,720
Speaker 1: a dense, rock hard sheet of ice. Eventually that becomes

14
00:00:50,720 --> 00:00:53,600
Speaker 1: a glacier, which is a towering pile of these sheets.

15
00:00:53,880 --> 00:00:56,040
Speaker 1: The oldest of those sit at the bottom of the glacier.

16
00:00:56,480 --> 00:00:59,000
Speaker 1: Scientists like to describe glacial ice as a kind of

17
00:00:59,080 --> 00:01:02,480
Speaker 1: annual record. While a new layer forms, tiny bubbles of

18
00:01:02,520 --> 00:01:05,920
Speaker 1: air get trapped inside. By analyzing that trapped air, they

19
00:01:05,920 --> 00:01:08,679
Speaker 1: can determine how much greenhouse gas was in the atmosphere

20
00:01:08,720 --> 00:01:11,920
Speaker 1: back when a given chunk of ice first solidified. Hardening

21
00:01:11,959 --> 00:01:15,120
Speaker 1: Glacial ice can also trap volcanic ash, which lets us

22
00:01:15,160 --> 00:01:18,480
Speaker 1: know when an ancient eruption must have taken place. Other

23
00:01:18,520 --> 00:01:21,480
Speaker 1: things extrapolated from the ice include the strength of prehistoric

24
00:01:21,480 --> 00:01:26,200
Speaker 1: winds and the global temperatures of bygone ages. This precious

25
00:01:26,200 --> 00:01:29,560
Speaker 1: information is harvested via drilling. With the help of mechanical

26
00:01:29,680 --> 00:01:32,760
Speaker 1: or thermal drills, a research team can extract a tall,

27
00:01:32,920 --> 00:01:37,000
Speaker 1: vertical cross section from a glacier. Glaciologists call these frozen

28
00:01:37,040 --> 00:01:40,400
Speaker 1: columns ice cores. The shortest are usually around a hundred

29
00:01:40,400 --> 00:01:43,039
Speaker 1: meters or three d and thirty feet long, but cores

30
00:01:43,120 --> 00:01:45,800
Speaker 1: stretching more than three kilometers or about two miles from

31
00:01:45,920 --> 00:01:49,480
Speaker 1: end to end have also been collected. During the extraction process,

32
00:01:49,520 --> 00:01:51,960
Speaker 1: a core is broken up into smaller pieces, which are

33
00:01:51,960 --> 00:01:55,240
Speaker 1: then placed into metal cylinders and stored in chilled laboratories.

34
00:01:56,040 --> 00:01:59,040
Speaker 1: A convenient feature of glaciers, at least for researchers, is

35
00:01:59,080 --> 00:02:01,680
Speaker 1: the fact that they're made up of annual layers. By

36
00:02:01,720 --> 00:02:04,640
Speaker 1: counting these, like tree rings, scientists can get a good

37
00:02:04,680 --> 00:02:07,920
Speaker 1: idea of how old an ice core segment is. Another

38
00:02:07,960 --> 00:02:12,320
Speaker 1: applicable technique is radiometric dating. Also helpful is the global

39
00:02:12,360 --> 00:02:15,320
Speaker 1: distribution of glaciers. There's at least one glacier on every

40
00:02:15,320 --> 00:02:18,920
Speaker 1: continent except Australia. Despite this, most of the ice cores

41
00:02:18,960 --> 00:02:22,000
Speaker 1: recovered so far were drilled in either Greenland or Antarctica.

42
00:02:22,440 --> 00:02:25,240
Speaker 1: That's not to say scientists are ignoring glaciers in other places.

43
00:02:25,680 --> 00:02:28,200
Speaker 1: In mid December, researchers announced that they had an ice

44
00:02:28,240 --> 00:02:30,799
Speaker 1: core of huge historical importance that was removed from the

45
00:02:30,840 --> 00:02:34,600
Speaker 1: Tibetan Plateau. The news comes out of Ohio State University,

46
00:02:34,600 --> 00:02:36,560
Speaker 1: which gave an update on the results of a joint

47
00:02:36,560 --> 00:02:39,960
Speaker 1: expedition by scientists from the school's Bird Polar and Climate

48
00:02:40,000 --> 00:02:43,600
Speaker 1: Research Center and the Chinese Institute of Tibetan Plateau Research.

49
00:02:44,200 --> 00:02:47,960
Speaker 1: Their venture began in September and October off when the

50
00:02:48,000 --> 00:02:50,480
Speaker 1: international party made its way to the Galia ice Cap

51
00:02:50,520 --> 00:02:54,600
Speaker 1: in Tibet's western Glenland Mountains. Accompanying them was six tons

52
00:02:54,720 --> 00:02:57,280
Speaker 1: or five point four metric tons of equipment that was

53
00:02:57,320 --> 00:03:01,280
Speaker 1: flown over from the United States. They're jective drill new

54
00:03:01,320 --> 00:03:04,720
Speaker 1: ice cores to enhance our knowledge of West Tibet's glacial history.

55
00:03:05,080 --> 00:03:07,639
Speaker 1: By investigating the past, we may be able to make

56
00:03:07,680 --> 00:03:11,840
Speaker 1: predictions about the area's uncertain future. More than one point

57
00:03:11,840 --> 00:03:14,400
Speaker 1: four billion people get their fresh water from the forty

58
00:03:14,440 --> 00:03:17,520
Speaker 1: six thousand glaciers that stand on the Tibetan Plateau, a

59
00:03:17,560 --> 00:03:20,720
Speaker 1: region nicknamed the Third Pole, but climate change has put

60
00:03:20,760 --> 00:03:23,720
Speaker 1: the area's long term stability in question. According to a

61
00:03:24,360 --> 00:03:27,040
Speaker 1: report published in the journal Nature, most of the glaciers

62
00:03:27,040 --> 00:03:29,720
Speaker 1: in Tibet have shrunk over the past thirty years, and

63
00:03:29,800 --> 00:03:32,120
Speaker 1: melting ice from Tibet's highlands has been cited as a

64
00:03:32,200 --> 00:03:36,040
Speaker 1: large contributor to the rise of global sea levels. Altogether,

65
00:03:36,080 --> 00:03:38,760
Speaker 1: the international team pulled five ice cores out of Galia.

66
00:03:39,320 --> 00:03:41,880
Speaker 1: The longest among them is a record holder at one

67
00:03:41,880 --> 00:03:45,200
Speaker 1: thousand feet that's about three five meters. It's nearly twice

68
00:03:45,240 --> 00:03:48,360
Speaker 1: as long as the Washington Monument is high. Even more

69
00:03:48,400 --> 00:03:51,520
Speaker 1: significant is its age. The lowest layers were formed around

70
00:03:51,560 --> 00:03:54,480
Speaker 1: six hundred thousand years ago. That's the oldest date ever

71
00:03:54,520 --> 00:03:56,880
Speaker 1: represented in an ice core that was found outside of

72
00:03:56,880 --> 00:04:00,480
Speaker 1: Earth's two polar circles. From a certain point of view,

73
00:04:00,520 --> 00:04:03,120
Speaker 1: it's still just a baby though. Some two point seven

74
00:04:03,160 --> 00:04:05,880
Speaker 1: million year old glacial ice was taken from an Antarctic

75
00:04:05,920 --> 00:04:09,880
Speaker 1: core in Still, that doesn't diminish the importance of these

76
00:04:09,920 --> 00:04:13,200
Speaker 1: new Tibetan cores. It isn't every day that humanity finds

77
00:04:13,360 --> 00:04:17,640
Speaker 1: six hundred millennia worth of preserved climate history. Plus any

78
00:04:17,680 --> 00:04:20,080
Speaker 1: addition to the global ice core supply will only benefit

79
00:04:20,120 --> 00:04:23,279
Speaker 1: future research. By consulting the cores found in different parts

80
00:04:23,320 --> 00:04:26,160
Speaker 1: of the world, scientists can figure out if historic weather

81
00:04:26,200 --> 00:04:30,000
Speaker 1: trends were universal or just regional. In the early twenty teens,

82
00:04:30,040 --> 00:04:33,800
Speaker 1: for example, scientists compared specimens from Tibet and Europe. The

83
00:04:33,880 --> 00:04:36,640
Speaker 1: data showed that while the latter continents saw temporary warm

84
00:04:36,680 --> 00:04:41,120
Speaker 1: period in medieval times, central Asia most likely didn't. Chinese

85
00:04:41,160 --> 00:04:43,680
Speaker 1: and American scientists will be putting these newfound cores through

86
00:04:43,680 --> 00:04:46,720
Speaker 1: an intensive chemical analysis over the next few months. We'll

87
00:04:46,760 --> 00:04:54,800
Speaker 1: keep you updated. Today's episode was written by Mark Mancini

88
00:04:54,880 --> 00:04:57,320
Speaker 1: and produced by Tristan McNeil. For more on this and

89
00:04:57,440 --> 00:05:00,400
Speaker 1: lots of other glacial topics, visit our home planet, faustive

90
00:05:00,440 --> 00:05:12,320
Speaker 1: works dot com. M