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Earth Systems > The Greenhouse Effect and Climate Change > Flashcards

The Greenhouse Effect and Climate Change Flashcards

1
Q

What would the average temperature of the Earth’s surface be without an atmosphere?

A
  • 15 degrees C
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2
Q

Is the Greenhouse Effect natural?

A
  • Not only is the Greenhouse Effect natural, without it we would freeze to death
    • Without it, the average Earth surface temperature would be about -15 DegC (258 K), or about 30 DegC (K) cooler than actual avg. temp (15 Deg C or 288 K)
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3
Q

Why can’t the majority of the Earths atmosphere absorb infrared radiation?

A
  • This is because the atmosphere is mainly composed of Nitrogen and Oxygen which are symmetrical and hence cannot provide electrons for the radiation to bounce off of.
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4
Q

Which parts of the Atmosphere are bale to absorb Infrared radiation?

A
  • Gases like Carbon dioxide and Argon are the main gases in the Atmosphere which are able to absorb infrared radiation and keep the Earth warm. They make up 1% of the Atmosphere and are such good infrared absorbers that they manage to intercept about 90% of Earths outgoing heat.
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5
Q

Where does radiation come from?

A
  • Every object in the universe
    emits energy or radiation
  • The hotter something is, the more radiation it emits and the relationship between temperature and radiation is exponential
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6
Q

What is the main form of energy produced by the Sun?

A
  • Visible light
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7
Q

What form does radiation come in?

A
  • Radiation comes in lots of forms: what we feel as heat and the basis for the Greenhouse Effect, is just one form of radiation
  • Infrared is the form that feels warm and, correspondingly, warm objects, such as cats, radiate infrared
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8
Q

How can you tell what kind of radiation is being emitted?

A
  • The main form of radiation an object emits is directly related to its temperature, according to Wien’s Law
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9
Q

What is Wiens Law

A

https://docs.google.com/document/d/11SlS_6djE3BGAezT2-FeVRTdxG1P1jVyj-u3X2L5qDo/edit?usp=sharing

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10
Q

What kind of wave length would a star hotter than the sun produce?

A
  • The hotter something is, the more it shifts towards a predominantly shorter wavelength radiation
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11
Q

What are the Sun and Earths main form of radiation?

A
  • The Sun ‘prefers’ to produce a shorter wavelength of energy than the Earth
  • The Earth’s ‘preferred’ energy form is in the region that feels warm – longwave or infrared
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12
Q

Draw and label the ‘Radiation Intensity vs Form of Radiation’ graph.

A

https://docs.google.com/document/d/11SlS_6djE3BGAezT2-FeVRTdxG1P1jVyj-u3X2L5qDo/edit?usp=sharing

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13
Q

What is the Solar Constant?

A
  • The radiation from the Sun that directly hits the Earth
  • The energy received at the top of the atmosphere on an area perpendicular to the direction of the incoming solar beam for the mean solar distance
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14
Q

Do we receive all of the suns radiation?

A
  • The amount of radiation generated by the Sun is huge

- But most of it goes into outer space – the Earth only receives a small portion

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15
Q

What is the Solar Constant for Earth?

A

= 1.37 KW m^-2
- But that is the concentrated amount that hits the Equator - remember, the energy will be spread out across higher latitudes
- Thus, the average solar radiation across the Earth is about 0.342 KW m^-2
• For simplicity, we say 0.342 KW m^-2 = 100 units

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16
Q

If the Sun releases 100 Energy Units to the Earth, what will happen to each of the units?

A
  • About 31 units will be reflected straight back into space
  • About 21 units will be absorbed by the atmosphere
  • About 48 units will make its way to Earth
  • About 5 units of radiation that makes it to Earth reflect back to outer space
17
Q

What happens to Earths radiation?

A
  • The Earth has to get rid of the radiation energy inputs at some point, has to be in energy balance.
  • It can’t simply destroy the radiation, but it can and does convert it.
  • Earth converts energy to longer wavelengths – like infrared
18
Q

What is Infrared?

A
  • Infrared is the wavelength we recognise as heat or warmth

- Earth’s radiation

19
Q

What kind of radiation does the Earth convert the suns radiation to?

A
  • The Earth re-emits the suns radiation as warm longwave radiation (Infrared)
20
Q

What does the Earths re-emitted radiation have to do with the atmosphere?

A
  • The Sun’s radiation that the Earth re-emits as warm long-wave radiation is the key to the Greenhouse Effect
21
Q

Why does Earths re-emitted radiation get stuck in the atmosphere?

A
  • The re-emitted long wavelength radiation meets gas molecules in the atmosphere that it could easily pass through when it came in from the Sun as short wavelength
  • However now it is long-wave and this makes it almost impossible to get through the gases.
22
Q

What happens to the infrared heat that is re-emitted into the atmosphere by the Earth?

A
  • Certain gases in the atmosphere are affected by infrared radiation – they absorb it and redistribute it throughout the atmosphere
  • The key for a gas to absorb infrared/heat is to have an unbalanced or asymmetrical structure in any direction
23
Q

What are the major human generated green house gases?

A
  • Carbon dioxide (CO2) – mainly from fossil fuel combustion and deforestation
  • Methane (CH4) – from energy production, agriculture and waste
  • Fluorine gases – from industrial processing
  • Nitrous oxide (N2O) – from agriculture
24
Q

What are the two main factors used to quantify the impact of GHG’s?

A
  • Radiative Forcing

- Gas Lifespan

25
Q

What is Radiative Forcing?

A
  • Basically the amount of infrared energy per area per time that a gas can absorb
26
Q

What is a Gas Lifespan?

A
  • How long the gas exists in the atmosphere before being broken down (e.g. CO2 is 100 years, CH4 is 12 years)
27
Q

What are the Radiative Forcing and Gas Lifespan used for?

A
  • Combined, these two factors are used to calculate the Global Warming Potential (GWP) for a gas.
  • CO2 is used as the standard reference, other gases are reported as CO2 -equivalents
28
Q

Fill in the GWP table for the green house gases.

A

https://docs.google.com/document/d/11SlS_6djE3BGAezT2-FeVRTdxG1P1jVyj-u3X2L5qDo/edit?usp=sharing

29
Q

What are the Atmospheric Concentrations of major GHG’s today?

A
  • CH4 = 1.8 ppm
  • CO2 = 400 ppm
  • N2O = 330 ppb
30
Q

What is the effect of increasing GHGs in the atmosphere?

A
  • It’s hard to predict on local scales with any great accuracy, some general trends are:
    1. Things gets hotter- increase of 1-2 Deg C by the end of the century
      1. Sea level rise
      2. Oceans get more acidic
      3. Ecosystems change rapidly
31
Q

What Climate Change Mitigation’s are being used and/or looked into?

A
  • Renewable energy sources
  • Carbon sequestration
  • Biogas recovery
  • Supressing enteric emissions (i.e., burps from livestock animals)
  • Biological methane removal
  • Nitrification inhibitors
32
Q

What is Carbon sequestration?

A
  • Putting emitted carbon back in the ground via:
    1) Biological processes
    2) Geo-sequestration
33
Q

What is Biogas recovery?

A
  • A lot of methane is produced in wastewater treatment or storage. It can be captured and burned for energy
34
Q

What is meant by: Supressing enteric emissions (i.e., burps from livestock animals)?

A
  • via feed additives, vaccines

- Enteric methane is a massive GHG source, this area of mitigation has promise but needs a lot more work

35
Q

What is Biological methane removal?

A

Where methane emissions are high but not concentrated enough to warrant biogas capture, filters comprising methane eating bacteria can be effective mitigation options

36
Q

What are Nitrification inhibitors?

A
  • Fertiliser – the largest source of N2O – can be amended with chemicals to slow the rate of nitrogen transformation in soil, and associated N2O emission

Earth Systems (13 decks)

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