Reading Ancient Climate Records · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Reading Ancient Climate Records

Science · Weather & Climate · ages 12-14
Name ______________________   Date ____________

  1. About how far back does the longest ice core record stretch?

    • 800 years
    • 800,000 years
    • 8,000 years

  2. What is trapped inside the layers of an ice core that lets scientists study the ancient atmosphere?

    • Tiny bubbles of ancient air
    • Liquid water only
    • Modern pollution particles

  3. Ash layers from volcanic eruptions found inside ice cores help scientists count the years accurately.

    Circle one:   True   False

  4. A tree grows a very narrow ring one year, right after several wide rings. What does the narrow ring most likely mean?

    • A harsh year, like a drought
    • A calm ocean current that year
    • A volcanic ash layer

  5. Scientists measure the ratio of two kinds of oxygen atoms in ice. What does that ratio mainly tell them?

    • How much it snowed that year
    • How deep the ice sheet is
    • The temperature when the snow fell

  6. Why do scientists use tree rings, ocean sediment, coral, and pollen together instead of trusting just one kind of record?

    • Ice cores are always wrong
    • Each proxy only covers certain places or time spans, so together they cross-check each other
    • Only pollen can show past temperature

  7. This chart shows CO2 trapped in ice-core bubbles at three points in time. How many parts per million higher is today's CO2 than the level from 800,000 years ago (420 minus 180)?

    800,000yrs ago180Before1800280Today420

    Answer: ______________

  8. A classmate says, 'Climate models are just made up because nobody can test them against real data.' What's the flaw in that claim?

    • Models truly cannot be tested at all
    • Models only use modern thermometers, never proxies
    • Models are run on the past and checked against ice cores and other proxy records
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Reading Ancient Climate Records W1-mt_olFzbawexJ-s1

  1. 800,000 years · The deepest ice cores hold about 800,000 years of layers, covering roughly 8 ice ages.
  2. Tiny bubbles of ancient air · As snow presses into ice, it seals tiny air bubbles inside. Those bubbles are a real sample of the ancient atmosphere.
  3. True · Since scientists already know the dates of many eruptions, an ash layer works like a bookmark for counting years.
  4. A harsh year, like a drought · Narrow rings form in harsh growing years. Ocean currents and ash layers show up in other kinds of records, not tree rings.
  5. The temperature when the snow fell · The isotope ratio changes with temperature, so it works like a thermometer built into the ice.
  6. Each proxy only covers certain places or time spans, so together they cross-check each other · No single proxy tells the whole story everywhere, so lining several up together makes the picture more reliable.
  7. 240 · Ice cores show CO2 was about 180 ppm long ago and is about 420 ppm today. 420 minus 180 is 240.
  8. Models are run on the past and checked against ice cores and other proxy records · Scientists validate a model by running it on the past and comparing the result to the real proxy record.
Worksheet · LightMySky