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    • Rights: Crown Copyright 2020, CC BY-NC-ND 4.0
    Published 15 October 2020 Referencing Hub media
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    James Renwick, Professor of Physical Geography at Victoria University of Wellington and climate change1 communicator, briefly explains climate change.

    Questions for discussion:

    • What are two ways of changing the climate2?
    • Which way is backed up by scientific evidence3?

    Transcript

    PROFESSOR JAMES RENWICK

    What’s going on at the moment is that the amount of energy within the Earth – that’s in the air and the water, the oceans and so on – is increasing. There’s more energy in the climate system, so everything is warming up and the cold things are melting, and that’s what people mean by climate change now.

    There are two ways to change the climate. Either the Sun becomes brighter or dimmer or the amount of greenhouse gas4 in the air goes up or down, because that’s the way that the Earth works.

    Sunlight comes into the Earth and the Earth absorbs that sunlight – mostly the oceans. And the Earth radiates5 heat energy6 back to space – the sort of energy our bodies put out – and that energy is absorbed into the atmosphere7 through greenhouse gases. And that’s very like having a blanket on a bed, and the blanket keeps you warmer because it traps some of that heat underneath. You put a thicker blanket on your bed, you get warmer. You put a thicker blanket of greenhouse gases on the Earth, and the Earth gets warmer. So that’s another way to warm the Earth – add greenhouse gas to the air or the Sun becomes brighter. Now we know the Sun is not becoming brighter – we measure that very accurately.

    It’s true that the climate has always been changing for billions of years. Geological records tell us the climate is actually sensitive. You tweak the amount of sunlight falling on the Earth a bit, you tweak the amount of greenhouse gases like carbon dioxide8 in the air a bit, and the temperature9 of the Earth, of the climate can change quite a lot.

    When the dinosaurs went extinct and further back in time, there have been some really rapid changes, but when you look as closely as we can, we’re still talking a thousand years minimum to see much of a change.

    So what’s happening today is that the amount of greenhouse gas in the air has gone up dramatically since the Industrial Revolution10 – a couple of hundred or getting on for 300 years ago now – when we started burning coal and oil for fuel11.

    Acknowledgements
    Greenhouse effect12 animation adapted from NASA animation What is the Greenhouse Effect?
    Ice core13 drilling footage from Drilling Back to the Future: Climate Clues from Ancient Ice on Greenland, Climate Central, released under CC BY-NC-ND 3.0
    Graphs of CO2 during the ice ages14 and CO2 emissions 1750–2019, courtesy of NOAA

    Acknowledgement

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

    1. 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.
    2. climate: The weather conditions of an area averaged over a series of years, usually 30 or more.
    3. evidence: Data, or information, used to prove or disprove something.
    4. 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.
    5. radiate: To emit, extend or spread rays from a central point.
    6. 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.
    7. atmosphere: 1. The layer of gas around the Earth. 2. (atm) A non-SI unit of pressure equivalent to 101.325 kPa.
    8. carbon dioxide: CO2 is a colourless, odourless, incombustible gas. It is a product of cellular respiration and combustion and is an essential component in photosynthesis.
    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. Industrial Revolution: The engineering revolution in the late 1700s and early 1800s that powered factories, railroads and steam ships and mechanised agriculture and textile manufacturing, leading to huge changes in society. It was not until the mid 20th century that the rise in CO2 emissions from burning fossil fuels became significant.
    11. fuel: 1. A combustible substance that provides energy. 2. A body fuel such as fat, carbohydrates and protein that supplies energy for animals’ activities.
    12. greenhouse effect: The process in which gases in the atmosphere trap heat from the sun and warm the Earth.
    13. 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.
    14. 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.

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    Ko e ha ‘a e feliuliuaki ‘a e ‘ea?

    Koe feliuliuaki ‘a e ‘ea ‘oku ‘uhinga ia ki he ngaahi liliu kehekehe ‘oku hoko ki he kalaimeiti (Churchward, 1959) ‘o e fo’i mamani, pea koe ngaahi liliu ko ‘eni ‘oku hoko ia ‘i ha fo’i vaha’a ...

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    • ARTICLE

    What is climate change?

    Climate change is defined as a long-term change to the Earth’s climate. But what does this mean? To understand climate change, we need to understand what makes up our climate. Rights: Crown ...

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      climate change

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      2. 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.

      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.

      atmosphere

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

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

      Industrial Revolution

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      5. The engineering revolution in the late 1700s and early 1800s that powered factories, railroads and steam ships and mechanised agriculture and textile manufacturing, leading to huge changes in society. It was not until the mid 20th century that the rise in CO2 emissions from burning fossil fuels became significant.

      ice core

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      6. 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.

      climate

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

      radiate

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      8. To emit, extend or spread rays from a central point.

      carbon dioxide

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      9. CO2 is a colourless, odourless, incombustible gas. It is a product of cellular respiration and combustion and is an essential component in photosynthesis.

      fuel

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      10. 1. A combustible substance that provides energy. 2. A body fuel such as fat, carbohydrates and protein that supplies energy for animals’ activities.

      ice age

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      11. 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.

      evidence

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      12. Data, or information, used to prove or disprove something.

      heat energy (heat)

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      13. 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.

      temperature

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      14. 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.

      greenhouse effect

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      15. The process in which gases in the atmosphere trap heat from the sun and warm the Earth.

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