WEBVTT
Kind: captions
Language: en

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It is -38° in here.

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I have never been anywhere this cold.

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I've had to insulate my camera so the batteries
keep working,

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and keep my microphone close to my body so
the wiring doesn't freeze and fall apart.

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This is the United States
National Ice Core Laboratory,

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in Denver, Colorado,

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and I figured it was best to interview
the scientists that work here

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outside this giant freezer.

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We have about 20,000 metres of ice
represented here

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and that's from probably, anywhere from 60-80
different boreholes around the world.

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The deepest one we have is about 3,600 metres
through the ice sheet of Antarctica.

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In our lab, the oldest ice that we have is
about 420,000 years old

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and that's from the Vostok Ice Core, drilled
in east Antarctica, back in the mid-90s.

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When a new core comes in,

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we piece it up and ship it out
to the principal investigators.

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All of this is meteoric ice,

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which means ice that's fallen from the sky.

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They don't want any of the tundra or sea ice,

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because it would contaminate
the meteoric ice that we have.

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One of the principal investigators who was
running an analysis

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can check his system from home,

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and he asked if somebody was eating
potato chips in the break room

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because he started seeing a
higher amount of sodium in his samples.

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And they, said, well... yeah(!)

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That's how sensitive this is.

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If the mains fail, we have
a natural-gas-fuelled generator out in back,

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it automatically switches power
to the freezer building.

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We're 100% backed up. On everything.

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Each one of these tubes contains
a sample of ice from the Arctic or Antarctic.

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And the deeper underground the core
was taken from, the older it is:

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all that fallen snow crushed down over perhaps
hundreds of thousands of years,

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along with anything else that happened to
be dragged along from the atmosphere.

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Pretty much anything that's in the atmosphere

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whether it's the atmospheric gases, or dust,
or anything like that,

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eventually lands on the ice sheets
of Antarctica and Greenland

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and will get buried and trapped
within the snow.

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And as that compresses into ice,
it preserves that information

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so we can actually use these ice cores

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to recreate what our
atmospheric chemistry was like

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dating back to about 850,000 years ago.

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We can also determine what global temperatures
were and how they changed over time

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by studying the stable isotopes of oxygen
within the water molecules.

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Essentially, they're looking at the ratio
between ¹⁶O and ¹⁸O.

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And by using a lot of modern-day studies,

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they can figure out what the temperature was

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in the area where that snow fell.

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There's a wide varieties of ways that we can
date these ice cores

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with Greenland cores, often times we can actual
see visible layers

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that change from summer to winter, based on
the dust concentration

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so, sort of like tree rings, count those seasons
going backwards

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and get a date that way.

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And then occasionally we'll run across things
like volcanic ash layers

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and if there's enough material
within an ash layer

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we can use radiometric dating to get
a very specific age on that volcanic layer.

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The margin of error in terms of our ages

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are usually within, you know,
±10 years or so.

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So it's pretty accurate, especially when we're
looking at ice

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that's a few hundred thousand years old.

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By understanding the natural variations of
climate change

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we can better predict what's going to happen
moving forward

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now that humanity has made
a pretty significant impact

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on what's going on with our planet

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in terms of the amount of greenhouse gases
that we've put into the atmosphere

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over the last century.

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We can better understand the past

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and using that knowledge of the past

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we can better model what's going to happen
moving forward into the future.

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Thank you to all the team here

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at the US National Ice Core Laboratory.

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Pull down the description for more about them
and about their work

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and I think my eyelids are sticking together?

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(You can't see it, but you do have frost all
on your eyelashes.)

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Really? (Yeah!)