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