How Much Can Ice Tell Us About Climate Change?

Ice cores from glaciers are like fossils of ancient Earth's weather patterns. Tune in to learn how one such sample from Tibet may hold an important history lesson.

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Episode Transcript

Speaker 1 (00:02):
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,

(00:22):
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.

(00:43):
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

(01:05):
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

(01:26):
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,

(01:49):
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

(02:12):
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,

(02:34):
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

(02:54):
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

(03:17):
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.

(03:39):
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,

(04:00):
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

(04:23):
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

(04:43):
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