Palaeoclimate: Ice Cores, Isotopes and the Record of Past Change · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Reading climates without thermometers

Science · Earth's Systems · ages 17-18
Name ______________________   Date ____________

  1. Why are trapped air bubbles so valuable in an ice core?

    • They keep the ice from melting
    • They mark where to drill next
    • They hold actual samples of ancient air

  2. What is a climate proxy?

    • A thermometer buried in ancient ice
    • Something that moved with temperature, standing in for it
    • A guess made without any evidence

  3. Proxies record past temperature directly, exactly like thermometers.

    Circle one:   True   False

  4. A scientist uses an isotope ratio as a thermometer. What must the report state?

    • The assumption linking the ratio to temperature
    • The brand of the measuring device
    • The name of the nearest glacier

  5. Shell oxygen ratios shift as ice sheets grow. What do they record?

    • The exact air temperature on that day
    • How much water was locked in ice when the shell formed
    • The age of the shell in years

  6. Ice-age cycles match slow orbit wobbles. What turns small nudges into full ice ages?

    • Scientists redrawing the graphs by hand
    • Orbit wobbles stopping completely
    • Amplifying responses like reflectivity and greenhouse gases

  7. Two records: an isotope series and an ice-core bubble series. Which compares gas and temperature directly?

    • The bubbles, since they trap ancient air itself
    • The isotopes, since ratios are always exact
    • Neither, since both need thermometers

  8. A student matches one cycle to orbit wobbles and claims orbit alone explains the full freeze. What is missing?

    • The exact year each wobble began
    • Proof that ice reflects no sunlight
    • The amplifying responses that grew the nudge
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Answer key

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

Reading climates without thermometers W1-mt_JabMZ5ZeaL-s1

  1. They hold actual samples of ancient air · Sealed bubbles let gas and temperature be compared directly.
  2. Something that moved with temperature, standing in for it · Proxies track temperature indirectly through a linked quantity.
  3. False · They record related quantities, so each reading needs an assumption.
  4. The assumption linking the ratio to temperature · Proxy science is only honest when its linking assumption is explicit.
  5. How much water was locked in ice when the shell formed · Growing ice sheets change the ocean mix the shell builds from.
  6. Amplifying responses like reflectivity and greenhouse gases · Orbit paces the cycle while feedbacks grow it into a full freeze.
  7. The bubbles, since they trap ancient air itself · Only bubbles hold the old atmosphere for a direct side-by-side read.
  8. The amplifying responses that grew the nudge · Without amplification, a small nudge stays small.
Worksheet · LightMySky