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    • Rights: Crown Copyright 2020
    Published 15 October 2020 Referencing Hub media
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    A climate1 oscillation is a recurring climate pattern – El Niño events, for example. Climate expert James Renwick explains how natural climate variations differ from climate variations due to climate change2.

    Questions for discussion:

    • What does James mean when he says natural variations just shift things (energy) around?
    • How does this differ to climate variations due to climate change?

    Transcript

    PROFESSOR JAMES RENWICK

    The climate does vary naturally for all sorts of reasons, and these so-called natural variations or oscillations involve energy. Heat3 is being shifted around from different parts of the world to somewhere else.

    A classic example is an El Niño in the tropics, where a whole lot of heat goes from near Australia and Indonesia and it shunts across the tropical Pacific to be closer to South America – happens over a matter of months – and it’s just moving energy, moving heat around within the oceans and the atmosphere4.

    The thing about these natural variations or oscillations is they don’t change the total amount of heat in the Earth, they just shift things around. So it’s getting cooler where you are because it’s getting warmer somewhere else. When you add it up around the globe, there’s no change.

    Another kind of natural oscillation, which does actually change the total temperature5 or energy of the Earth, is something like the Ice Ages6. This is a classic example where, over 100,000 years or so, the Earth goes from a climate like we have today to one where the continents7 are covered in a couple of kilometres of ice and it’s several degrees colder than present. And that happens because sunlight changes – so that the Sun basically becomes a bit dimmer.

    Acknowledgements
    Professor James Renwick, Victoria University of Wellington
    El Niño weather pattern animation, NIWA
    Animations of ice age freezing across Earth globe and permafrost from The Last Time the Globe Warmed, Curiosity Stream, PBS Eons
    Woolly mammoths illustration, Mauricio Antón, released under CC BY 2.5

    Acknowledgement

    This resource has been produced with the support of the Ministry for the Environment and Stats NZ. (c) Crown Copyright.

    1. climate: The weather conditions of an area averaged over a series of years, usually 30 or more.
    2. climate change: The large-scale, long-term increase in the Earth’s average temperatures, with associated changes in weather patterns. There is significant scientific evidence that warming is due to increased quantities of greenhouse gases in the atmosphere, with most of the rise due to human activity.
    3. heat energy (heat): Heat energy: the transfer of energy in materials from the random movement of the particles in that material. The greater the random movement of particles the more heat energy the material has. Temperature is a measure of the heat energy of a material.
      Heat: the flow of energy from a warm object to a cooler object.
    4. atmosphere: 1. The layer of gas around the Earth. 2. (atm) A non-SI unit of pressure equivalent to 101.325 kPa.
    5. 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.
    6. ice age: Ice ages occur when the Earth’s climate cools and large areas of land and sea become covered by vast ice sheets. The Earth has experienced many ice ages in its lifetime.
    7. continent: In geology, any of the main continuous expanses of continental crust on the Earth. Africa, Antarctica, Asia, Australia, Europe, North America and South America are recognised as continents, but this is based on historical and cultural attributes rather than geological attributes.

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      • Go to full glossary
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      climate

    1. + Create new collection

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

      atmosphere

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

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

      continent

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      4. In geology, any of the main continuous expanses of continental crust on the Earth. Africa, Antarctica, Asia, Australia, Europe, North America and South America are recognised as continents, but this is based on historical and cultural attributes rather than geological attributes.

      climate change

    4. + Create new collection

      5. The large-scale, long-term increase in the Earth’s average temperatures, with associated changes in weather patterns. There is significant scientific evidence that warming is due to increased quantities of greenhouse gases in the atmosphere, with most of the rise due to human activity.

      temperature

    5. + Create new collection

      6. 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.

      heat energy (heat)

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      7. Heat energy: the transfer of energy in materials from the random movement of the particles in that material. The greater the random movement of particles the more heat energy the material has. Temperature is a measure of the heat energy of a material.
      Heat: the flow of energy from a warm object to a cooler object.

      ice age

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      8. Ice ages occur when the Earth’s climate cools and large areas of land and sea become covered by vast ice sheets. The Earth has experienced many ice ages in its lifetime.

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