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    • Rights: The University of Waikato
    Published 21 June 2007 Referencing Hub media
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    Dr Katja Riedel of NIWA explains how ice cores1 are dated. The researchers often rely on events like volcanic eruptions to determine how old the ice is.

    Transcript

    DR KATJA RIEDEL
    We date ice cores by looking into historic events that we know how and when they happened. And a very good thing is volcanic eruptions. When you have a volcano erupting you have ash for example in the atmosphere2. And this ash layer can travel around the globe, and then also is deposited in Antarctic ice cores. So you might be able to see a kind of darkish layer in an ice core3 and then you know exactly when this volcanic eruption was, and that is how you date your ice.

    When we put together all what we find out about gas concentrations, about gas isotopes4, what we’re looking for is information is where these greenhouse gases5 came in the past. How this change in greenhouse gas6 concentrations led to a different climate7 on Earth. Cause from the oxygen8 isotopes we also can have an idea of what the temperature9 was at the Earth. So we really see how temperature and greenhouse gas concentrations work together, and that will help us to understand how nowadays concentrations of greenhouse gases10, which are increasing, work together with climate.

    1. ice core: A core sample, typically removed from an ice sheet. Ice cores are long cylinders of ice recovered by drilling with a hollow bit. Ice cores contain information about past climates.
    2. atmosphere: 1. The layer of gas around the Earth. 2. (atm) A non-SI unit of pressure equivalent to 101.325 kPa.
    3. ice core: A core sample, typically removed from an ice sheet. Ice cores are long cylinders of ice recovered by drilling with a hollow bit. Ice cores contain information about past climates.
    4. isotope: Different forms of atoms of the same element. Within the nucleus, there is the same number of protons but a different number of neutrons, giving each isotope a different atomic mass.
    5. greenhouse gases: A natural or manmade gas that traps heat in the Earth's atmosphere and contributes to the greenhouse effect. The main greenhouse gases are water vapour, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone and industrial gases such as chlorofluorocarbons (CFCs). These gases in the Earth's atmosphere trap warmth from the Sun and make life possible. An overabundance of greenhouse gases leads to a rise in global temperatures – known as the greenhouse effect.
    6. greenhouse gases: A natural or manmade gas that traps heat in the Earth's atmosphere and contributes to the greenhouse effect. The main greenhouse gases are water vapour, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone and industrial gases such as chlorofluorocarbons (CFCs). These gases in the Earth's atmosphere trap warmth from the Sun and make life possible. An overabundance of greenhouse gases leads to a rise in global temperatures – known as the greenhouse effect.
    7. climate: The weather conditions of an area averaged over a series of years, usually 30 or more.
    8. oxygen: A non-metal – symbol O, atomic number 8. Oxygen is a gas found in the air. It is needed for aerobic cellular respiration in cells.
    9. temperature: A measure of the degree of hotness or coldness of an object or substance. Temperature is measured with a thermometer calibrated in one or more temperature scales. Kelvin scale temperature is a measure of the average energy of the molecules of a body.
    10. gases: The state of matter distinguished from the solid and liquid states. Gases have the ability to diffuse readily and to become distributed uniformly throughout any container.

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      ice core

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      2. A core sample, typically removed from an ice sheet. Ice cores are long cylinders of ice recovered by drilling with a hollow bit. Ice cores contain information about past climates.

      greenhouse gases

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      3. A natural or manmade gas that traps heat in the Earth's atmosphere and contributes to the greenhouse effect. The main greenhouse gases are water vapour, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone and industrial gases such as chlorofluorocarbons (CFCs). These gases in the Earth's atmosphere trap warmth from the Sun and make life possible. An overabundance of greenhouse gases leads to a rise in global temperatures – known as the greenhouse effect.

      temperature

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      4. A measure of the degree of hotness or coldness of an object or substance. Temperature is measured with a thermometer calibrated in one or more temperature scales. Kelvin scale temperature is a measure of the average energy of the molecules of a body.

      atmosphere

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      5. 1. The layer of gas around the Earth.

      2. (atm) A non-SI unit of pressure equivalent to 101.325 kPa.

      climate

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      6. The weather conditions of an area averaged over a series of years, usually 30 or more.

      gases

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      7. The state of matter distinguished from the solid and liquid states. Gases have the ability to diffuse readily and to become distributed uniformly throughout any container.

      isotope

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      8. Different forms of atoms of the same element. Within the nucleus, there is the same number of protons but a different number of neutrons, giving each isotope a different atomic mass.

      oxygen

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      9. A non-metal – symbol O, atomic number 8. Oxygen is a gas found in the air. It is needed for aerobic cellular respiration in cells.

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