Speaker 1: Welcome to Brainstuff from how Stuff Works, Hey, brain Stuff,
Speaker 1: Lauren Vogel bomb here the history of life is chronicled
Speaker 1: in our fossil record. Scientists use skeletons, trackways, and other
Speaker 1: tangible calling cards to learn new things about prehistoric organisms.
Speaker 1: But how do they study prehistoric climates? Unlike dinosaurs or mastodon's,
Speaker 1: the climate has no bones to leave behind, no footprints
Speaker 1: to track. Telltale indicators of past weather conditions can still
Speaker 1: be found, though, if you know where to look for them.
Speaker 1: One important line of evidence lies inside the world glacial ice.
Speaker 1: Glaciers form where snow is steadily accumulating but not melting. Slowly,
Speaker 1: the weight of new layers deforms the snow crystals below them.
Speaker 1: The compression fuses old buried snowflakes together until they become
Speaker 1: a dense, rock hard sheet of ice. Eventually that becomes
Speaker 1: a glacier, which is a towering pile of these sheets.
Speaker 1: The oldest of those sit at the bottom of the glacier.
Speaker 1: Scientists like to describe glacial ice as a kind of
Speaker 1: annual record. While a new layer forms, tiny bubbles of
Speaker 1: air get trapped inside. By analyzing that trapped air, they
Speaker 1: can determine how much greenhouse gas was in the atmosphere
Speaker 1: back when a given chunk of ice first solidified. Hardening
Speaker 1: Glacial ice can also trap volcanic ash, which lets us
Speaker 1: know when an ancient eruption must have taken place. Other
Speaker 1: things extrapolated from the ice include the strength of prehistoric
Speaker 1: winds and the global temperatures of bygone ages. This precious
Speaker 1: information is harvested via drilling. With the help of mechanical
Speaker 1: or thermal drills, a research team can extract a tall,
Speaker 1: vertical cross section from a glacier. Glaciologists call these frozen
Speaker 1: columns ice cores. The shortest are usually around a hundred
Speaker 1: meters or three d and thirty feet long, but cores
Speaker 1: stretching more than three kilometers or about two miles from
Speaker 1: end to end have also been collected. During the extraction process,
Speaker 1: a core is broken up into smaller pieces, which are
Speaker 1: then placed into metal cylinders and stored in chilled laboratories.
Speaker 1: A convenient feature of glaciers, at least for researchers, is
Speaker 1: the fact that they're made up of annual layers. By
Speaker 1: counting these, like tree rings, scientists can get a good
Speaker 1: idea of how old an ice core segment is. Another
Speaker 1: applicable technique is radiometric dating. Also helpful is the global
Speaker 1: distribution of glaciers. There's at least one glacier on every
Speaker 1: continent except Australia. Despite this, most of the ice cores
Speaker 1: recovered so far were drilled in either Greenland or Antarctica.
Speaker 1: That's not to say scientists are ignoring glaciers in other places.
Speaker 1: In mid December, researchers announced that they had an ice
Speaker 1: core of huge historical importance that was removed from the
Speaker 1: Tibetan Plateau. The news comes out of Ohio State University,
Speaker 1: which gave an update on the results of a joint
Speaker 1: expedition by scientists from the school's Bird Polar and Climate
Speaker 1: Research Center and the Chinese Institute of Tibetan Plateau Research.
Speaker 1: Their venture began in September and October off when the
Speaker 1: international party made its way to the Galia ice Cap
Speaker 1: in Tibet's western Glenland Mountains. Accompanying them was six tons
Speaker 1: or five point four metric tons of equipment that was
Speaker 1: flown over from the United States. They're jective drill new
Speaker 1: ice cores to enhance our knowledge of West Tibet's glacial history.
Speaker 1: By investigating the past, we may be able to make
Speaker 1: predictions about the area's uncertain future. More than one point
Speaker 1: four billion people get their fresh water from the forty
Speaker 1: six thousand glaciers that stand on the Tibetan Plateau, a
Speaker 1: region nicknamed the Third Pole, but climate change has put
Speaker 1: the area's long term stability in question. According to a
Speaker 1: report published in the journal Nature, most of the glaciers
Speaker 1: in Tibet have shrunk over the past thirty years, and
Speaker 1: melting ice from Tibet's highlands has been cited as a
Speaker 1: large contributor to the rise of global sea levels. Altogether,
Speaker 1: the international team pulled five ice cores out of Galia.
Speaker 1: The longest among them is a record holder at one
Speaker 1: thousand feet that's about three five meters. It's nearly twice
Speaker 1: as long as the Washington Monument is high. Even more
Speaker 1: significant is its age. The lowest layers were formed around
Speaker 1: six hundred thousand years ago. That's the oldest date ever
Speaker 1: represented in an ice core that was found outside of
Speaker 1: Earth's two polar circles. From a certain point of view,
Speaker 1: it's still just a baby though. Some two point seven
Speaker 1: million year old glacial ice was taken from an Antarctic
Speaker 1: core in Still, that doesn't diminish the importance of these
Speaker 1: new Tibetan cores. It isn't every day that humanity finds
Speaker 1: six hundred millennia worth of preserved climate history. Plus any
Speaker 1: addition to the global ice core supply will only benefit
Speaker 1: future research. By consulting the cores found in different parts
Speaker 1: of the world, scientists can figure out if historic weather
Speaker 1: trends were universal or just regional. In the early twenty teens,
Speaker 1: for example, scientists compared specimens from Tibet and Europe. The
Speaker 1: data showed that while the latter continents saw temporary warm
Speaker 1: period in medieval times, central Asia most likely didn't. Chinese
Speaker 1: and American scientists will be putting these newfound cores through
Speaker 1: an intensive chemical analysis over the next few months. We'll
Speaker 1: keep you updated. Today's episode was written by Mark Mancini
Speaker 1: and produced by Tristan McNeil. For more on this and
Speaker 1: lots of other glacial topics, visit our home planet, faustive
Speaker 1: works dot com. M