Climate Change Flashcards

1
Q

What is climate?

A

“average weather”, the classical period is 30 years, variables include: temperature, precipitation, and wind

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2
Q

What five factos determine the surface temperature of the earth?

A
  1. energy balance
  2. greenhouse effect
  3. carbon cycle
  4. radiative forcing
  5. feedback mechanisms
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3
Q

What is a blackbody?

A

a material that absorbs all light - 100% absorption, 0% reflection

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4
Q

What is blackbody radiation?

A

the spectrum of light from an object that does not create light

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5
Q

What is albedo?

A

fraction of sunlight reflected back into space by an object

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6
Q

what is dE? What contributes to most of the greenhouse effect?

A

dE = absorption and thermal radiation of GHGs = green house effect

water vapour accounts for most of the effect

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7
Q

What happens to the IR light that is absorbed by GHGs?

A
  1. reemitted after absorption
  2. lost as heat through collisions with other molecules
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8
Q

What is the greeenhouse effect?

A

absorption of outgoing IR by atmosphere and dissipation of heat

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9
Q

What increases the chance of IR absorbance by molecules?

A

When the hv approaches the molecular vibrational modes

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10
Q

What are common molecular vibrations?

A
  1. bond stretching vibrations: symmetic or asymmeric
  2. angle-bending vibrations
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11
Q

What condition does IR absorption by molecules require, in terms of vibrations?

A

requires a change in the dipole moment during the vibration

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12
Q

What happens after vibrational excitation?

A

molecules move faster –> more collisions –> transfer of E to other molc during collision –> relaxation + release of heat (+emit IR as heat) –> IR absorbed by a neighboring molc

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13
Q

What is radiative forcing?

A

term used to describe the radiative imbalance caused by species in the atmosphere, based on both concentration and impact (e.g. a poorer absorber at a higher concentration can have a larger impact = greater RF)

> 0 = warming influence
< 0 = cooling influence

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14
Q

Why does the [CO2] have seasonality?

A
  • N. hemisphere is where most vegetation is located
  • CO2 build up until growing season begins, then decreases via photosynthesis
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15
Q

Where is most carbon stored? How has human activity changed the carbon cycle?

A

most C is stored in rocks, sediment (including fossil fuels), then rest in ocean, atmosphere, and living organisms

human activity

  • increase release of CO2
  • change of land use (deforestation, building over peat bogs) –> less CO2 is removed by photosynthesis
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16
Q

What are major sources of CO2?

A

combustion: CxHy + O2 –> CO2 + H20
cement production: CaCO3 –> CaO + CO2

17
Q

Is CH4 a better or worse GHG than CO2?

A

better - absrobs IR more frequently than CO2

18
Q

What are common sources for atmospheric CH4?

A
  • anaerobic decomposition: convert cellulose into CH4 and CO2 (occurs at landfills and in livestock)
  • biomass burning (from incomplete combustion)
  • leaking natural gas lines
  • mining of coal
  • collecting/refining crude oil releases dissolved CH4 or gens it from incomplete flaring
19
Q

Describe the role of aerosols on climate forcing

A
  • scattering (increase albedo = negative RF; redirect thermal IR downwards = postivie RF)
  • absorption (positive RF)
  • can cause increased cloud formation (increased albedo = negative RF)
20
Q

How is radiative forcing (RF) calculated?

A

spectral overlay for the absorption of IR by GHGs compared to the spectral emisssion of Earth

21
Q

What GHG is currently a huge concern?

A

SF6

22
Q

What is the Koyoto protocol?

A

decrease GHG emissions

23
Q

What is the Montreal Protocol?

A

phase 1: no more halogenated (e.g. CFCs)
phase 2: phase out HCFC

24
Q

What is the Kigali ammendment of the Montreal protocol?

A

phase down HFCs and HFOs

25
Q

What are the positives of HFO and what is a big side effect?

A

good = shorter residence time –> less persistant –> smaller GWP

bad = large yield of TFA (a forever chemical)