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Climate Change > lecture 1 - 15 > Flashcards

lecture 1 - 15 Flashcards

1
Q

Difference between climate and weather

A

Climate is the average weather - extended period of time

Weather is the state of the atmosphere at a given time

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2
Q

Example of annectodal climate change

A

Hurricane dorian is ghe worst hurricane ever recorded in the bahamas

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3
Q

What does the surface weather station stevenson screen measure?

A

Temperature, humidity, pressure. Wind

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4
Q

What are weather balloons used for?

A

Profile lowest 30 km of the atmos twice a day around the world

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5
Q

Climate change evidence #1 is the global mean surface temp - how is this evidence of climate change

A

Global average is increasing, hottest period since 1980

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6
Q

What are the four strong evidence for climate change

A

Mean surface temp increasing

Global mean sea level rising

Arctic sea ice extent - declining

Increasing atmospheric carbon dioxide + ocean acidification

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7
Q

Explain hydrostatic balance in the atmosphere

A

Atmo pressure and air density decrease exponentially with height

Decreasing air pressure w height makes an upward pressure force the balance the downward force of gravity

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8
Q

Where do clouds and precipitation occur in the atmosphere?

A

Troposphere

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9
Q

What are the greenhouse gases

A 
Water vapour
CO2
Methane
Nitrous oxide
Ozone
CFCs
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10
Q

99.9% of the dry atmosphere consists of what gases?

A

Nitrogen
Oxygen
Argon

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11
Q

Where is the ozone layer found in the atmosphere

A

Stratosphere

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12
Q

What is tropospheric ozone?

A

Air pollution

Made from nitrous oxide emitted from fossil fuel burning

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13
Q

What is residence time

A

Average lifetime of a molecule in armosphere

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14
Q

What is a steady state

A

Inflow rate (sources) equal the outflow rate (sinks)

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15
Q

Explain the bathtub analogy for residence time

A

Resevior is like a bathtub

If the atmos gas concentration stay the same, then the source and sinks must equal each other

Water flow into tub must equal water flow out of tub

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16
Q

Which gases have the longer residence time in the atmosphere?

A

Nitrogen and oxygen

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17
Q

Why are the oceans a key factor in determining climate and climate change

A

Ability to store and transoprt huge amounts of energy and delay the temperature response because of its heat capacity

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18
Q

What is the thermocline?

A

Layer where the ocean temp decreases rapidly with depth

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19
Q

Why is the deep ocean cold?

A

Because the water comes from the polar sea surface

Densest surfa e waters are near the poles —> denser water sinks —> this supplies cold eater in the deep ocean

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20
Q

What is the eath’s energy balance

A

Incoming solar energy absorbed = terrestrial infrared radiation emitted to space

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21
Q

What are the properties of an electromagnetic wave

A

Wavelength, frequency, amplitude

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22
Q

The analysis of radiation by wavelength or frequency is called

A

Spectroscopy

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23
Q

What is thermal radiation

A

Radiation emitted by substance because of its temp

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24
Q

As a substance gets hotter, the emitted thermal radiation wavelength gets longer or shorter

A

Shorter

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25
Q

A materials ability to emit radiation is the same as it’s ability to…

A

Absorb radiation

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26
Q

What is black body radiaiton

A

Efficiency is 100% to absorb and emit radiation

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27
Q

What is infrared radiation

A

Invisible radiaiton

Wavelengths that are longer thsn the visible red wavelengths

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28
Q

What are the two types of radiation important for climate change

A
  1. Solar infrared radiation - shortwave, emitted by sun, makes up 1/2 solar radiation
  2. Terrestrial infrared radiation- longwave, emitted by earth and atmosphere, STRONGLY ABSORBED AND EMITTED BY GREENHOUSE GASES AND CLOUDS
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29
Q

Which electromagnetic waves can transmit through the earth’s cloudless atmosphere

A

Some UV, most visible light, some infrared, some microwave and some radio

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30
Q

What causes the greenhouse gas effect

A

Complete of partial blocking of some of the infrared wavelengths

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31
Q

The fraction of incoming radiation that id reflected by an object is called the … of the object

A

Albedo

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32
Q

What does an albedo of 1 mean? How about 0?

A 
1 = 100% reflected
0 = 0% reflected, all is absorbed
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33
Q

The average planetary albedo is 0.3, what does this mean?

A

30% of incoming radiation is reflected, 70% is absorbed

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34
Q

What reflects most of the sunlight and what absorbs most of it?

A

Relfects = clouds, ice, desertd

Absorbs = trees/forest, oceans

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35
Q

What is the effective planetary temperature

A

Temp earth appears to emit from space

Teff must be big enough to make enough outgoing thermal radiation to balance the net incoming solar radiation

Increases if more solar radiation
Decreases if earth gets higher albedo

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36
Q

Why is the effective planetary temperature lower/colder than the actual observed average surface temp?

A

Teff does not take into account the greenhouse gas effect which raises the surface temp

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37
Q

What 3 factors determine the globally averaged surface temperature

A

Amount of incoming solar
Albedo of earth
Greenhouse gas effect

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38
Q

The terrestrial infrared radiation gets progressively more blocked as the greenhouse gas concentration increases. Why?

A

Greenhouse gases absorb and emit at certain terrestrial infrared wavelengths

Increasing amount of g gases reduce the penetration depth of the terrestrial infrared radiation at the specific wavelengths that interact with the g gases

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39
Q

What happens if the atmosphere becomes more opaque at cetain wavelengths?

A

The radiation at those wavelengths can’t penetrate as far

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40
Q

Radiation that escapes to space starts from colder, higher up regions of the atmosphere where radiation reaching the ground starts from lower down. How does the increasing opaqueness of the atmosphere effect the greenhouse gas effect?

A

More opaque, radiation can’t penetrate as far into the atmosphere

More radiation reaches the ground + g gas effect is larger

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41
Q

How does adding g gases warm the earth

A

G gas concentrations increase - atmos more opaque

Penetration depth of infrared radiation is reduced - can’t travel as far

outgoing terrestrial radiation escaling to space comes from higher up in the atmos where it is colder

Colder atmos release less thermal radiation

Results - earth releasing less terrestrial bc of g gases but the net incoming solar is staying the same

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42
Q

Why is global warming happening (essentially)

A

The extra g gases are making the atmosphere less transparent in the infrared

Net incoming solar radiation energy is larger than the outgoing terrestrial

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43
Q

Where does the accumulated energy from the imbalance of solar snd terrestrial radiation go?

A

94% to ocean warming and 3% to melting ice sheets, 3% to heating land

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44
Q

Will the energy imbalance between solar and terrestrial persist forever?

A

No - it will eventually reach a new steady state

Ocean, land and air temp sill increase gradually and gradually increase the amount of terrestrial infrared escaping to space

But new steady state will have higher surface temp

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45
Q

How is the current energy surplus that the earth is experiencing being used up?

A

Heating ocean
Melting ice sheets and glaciers
Heating land and sub-surface

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46
Q

Explain the difference between a maritime climate and a continental climate

A

The heat capacity of the oceans imposes a time delay In the climate system

Takes longer to heat oceans

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47
Q

What are some consequences of the high heat capacity of the oceans

A

Warmest summer temp occur month of two after max solar energy on june 21

Annual temp extremes are smaller nearest ocean

Full impact of global warming is delayed while oceans warm up

Tropical oceans are heat sources to drive tropical cyclones

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48
Q

Why are the poles cold?

A

Earths angle, solar radiation near pole is spread out over a larger area, so less energy per unit area

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49
Q

Why do we experience seasons?

A

Earth’s tilt

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50
Q

What are the two types of local radiative energy imblanaces

A
  1. Net radiative surplus (positive) over the tropics and net radiative deficit over the poles
  2. Locally earth;s surface has a surplus whereas local atmos above has a deficit
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51
Q

What motion does the energy imbalance of the poles and equator drive?

What about the local imbalance of the surface and the atmos?

A

Pole-equator - drives the meridional dynamics / motion of the atmosphere and the oceans

Locally - drives the vertical dynamics the lower atmos (troposphere)

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52
Q

The latitudinal imbalance in radiative energy get balanced in total by what..

A

The internal dynamical motions of the at atmos and oceans

Transfers sensible and latent heat from thd tropics to the poles

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53
Q

What internal dynamical processes transfer sensible and latent heat from the tropics to the poles?

A

Had;ey cells, tropical cyclones, extratropical cyclones snd ocean circulstion

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54
Q

Explain the net radiative imbalance between the atmosphere and the surface?

A

Surface has net radiative heating
Atmos has net radiative cooling

*turbulence, convection, thunderstorms - transfers surface heating to atmosphere so that total energy balance occurs everywhere

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55
Q

What is the earth’s general circulation?

A

Transfers sensible and latent heat from regions of net radiative heating to regions of net radiative cooling

Dynamical motions set in place to achieve local energy balance everywhere

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56
Q

What are the two main climate regimes?

A
  1. Tropical and sub-tropical
    (30 deg n and s)
  2. Extra-tropical
    (Poleward of 30 deg latitude)
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57
Q

Explain the tropical and subtropics climate regime

A 
30 deg n and s
Horizontally uniform temp
Active weather (thunderstorms, tropical cyclones 
Weak seasonality 
Monsoons, hadley cells
Easterly trade winds
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58
Q

Monsoons are a heat capacity effect. Explain

A

Air over land is warmer than ocean air in the summer —> oceans have large heat capacity, don’t warm up as fast

Sets up a circulation of air - warm rises over land and cool sinks down over ocean

This cycle reverses in the winter - seasonal varying rainfall is called monsoon

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59
Q

What drives the thermohaline ocean circulation

A

Local net radiation imbalance

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60
Q

What is the thermohaline ocean circulation

A

Deep circulation
Transfers heat, water and salt
Caused by ocean water density differences
Densities determined by temp and salinitydifferences

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61
Q

Where does the oceans deep water come from?

A

Greenland and the antarctic seas

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62
Q

Consider an atmosphere with no greenhouse gases and no clouds. How would this effect the energy of the earth?

A

It would be in a steady state / balanced

Atmos transparent to long-wave terrestrial and not emit any longwave

Surface temp would be the effective planetsry temp (-18 deg)

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63
Q

No consider an atmos with greenhouse gases and clouds creating a “blanket” in the atmos. Explain the blanket analogy

A

G gases emit more terrestrial infrared back to the ground than to space because its warmer in the atmos closer to the ground

Top of blanket is colder - less emitted
Bottom of blanket warmer - more emitted

Amount of infrared emitted depends in temp

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64
Q

Why does the planet need the greenhouse gas effect

A

Without it, surface temp would be teff (-18 deg) and freeze all water and life as we know it - greenhouse gas effect helps keep the planet warm and liveable

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65
Q

What is radiative forcing

A

Chg in net total radiation at the top of the atmos which occurs bc of a chg in climstr system (i.e increasing co2, changing solar input, adding volcanic aerosols)

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66
Q

The net total radition is the difference between what

A

Between downward and upward solar shortwave and terrestrial infrared radiation

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67
Q

What happens to the terrestrial infrared radiation if we instantly double the amount of carbon dioxide

A

The surface temp is still at 15 deg

The blanket is thicker
Penetration depth of long-wave ir is reduced
Stronger absorption of long-wave ir
Top of the blanket is now colder because the long-wave being emitted to space is at a higher altitude

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68
Q

What happens to the terrestrial infrared radiation if we double the amount of carbon dioxide and a new steady state is established

A

The warming of the atmos and surface continues until teff emitting level of terrestrial IR to space is back at -18

The surface temp will warm by 3 deg to 18 deg

This change takes time because of the oceans time delay

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69
Q

What causes the greenhouse gas effect

A

Emission of terrestrial infrared radiation by g gases and clouds downward to the earth’s surface

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70
Q

Is venus’ surface warmer because it’s closer to the sun?

A

No

It has a stronger greenhouse gas effect

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71
Q

What is a greenhouse gas

A

Molecule that can absorb terrestrial infrared radiation with wavelengths in the 4-100 um

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72
Q

How many atoms does a greenhouse gas have

A

3 atoms or more

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73
Q

Greenhouse gases are… or… atomic molecules

A

Tri or polyatomic

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74
Q

Greenhouse gases are tri or polyatmoic molecules giving them different vibrational modes. How does this effect their ability to absorb and emit in the infrared?

A

If vibrational mode matches the infrared radiation wave frequency, the molecule can emit or absorb

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75
Q

What are the 5 greenhouse gases

A 
Methane
CO2
Water vapour
Nitrous oxide
Ozone
Halocarbons
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76
Q

What are the two vibrational modes of carbon dioxide? Explain them

A

Bond stretching and bond bending

The two frequencies correspond to specific wavelengths in the terrestrial infrared where they can emit and absorb

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77
Q

What contributed to the natural greenhouse effect

A

Water vapour
Clouds
Other gases (mostly CO2)

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78
Q

What is the natural greenhouse gas effect?

A

Warms the earth surface from the teff of -18 deg to the actual surface temp of 15 deg

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79
Q

What accounts for 70% of the natural greenhouse gas effect

A

Water vapour and clouds

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80
Q

Why does the concentration of CO2 oscillate annually?

A

Global photosynthesis and respiration

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81
Q

When do the co2 concentrations show a minimum globally? What about an increase?

A

Minimum during nothern hemispheric autumn after summer’s new biomass growth removes co2 through photosynthesis

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82
Q

How do we know the pre-industrial co2 concentrations of about 280ppm?

A

Air bubbles trapped in ice cores drilled from the Greenland and antarctic ice sheets

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83
Q

What are the main anthropogenic sources of methane

A 
Rice paddies
Cattle
Biomass burning
Fossil fuels
Landfills
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84
Q

What are some natural sources of methane?

A

Wetlands

Lakes, termites, oceans, permsfrost

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85
Q

What is a natural sink of methane

A

Chemical reactions in atmos

Sink in soils

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86
Q

What is most of the increase in nitrous oxide emissions from?

A

Agricultural sctivites
Fertilizer
Animal production

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87
Q

What is the global warming potential

By definition the gwp of co2 is always..

A

Radiative forcing of a gas averaged over the given time period compared to same mass of co2

Gwp is always 1

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88
Q

The extent to which a greenhouse gas directly contributes to climate change depends on what 3 things

A

Quantity of gas
Time before its removed from atmos
Infrared energy absorption propreties

89
Q

The global warming potential is usually averaged over what length of a time period

A

100 year time period

90
Q

Methane is 23 times more potent as a greenhouse gas than co2 but co2 still exerts more radiative forcing than methane in the atmosphere… why?

A

Because there’s more co2 in the atmos

91
Q

The gwp potential of nitrous oxide is much larger than methane because…

A

Nitrous oxide has a longer lifetime than methane

92
Q

Why does water vapour not have a global warming potential

A

Because it’s a natural greenhouse gas nad only has a lifetime of 1 week

93
Q

What is equivalent co2

A

Concentration of co2 that would result the same level of radiative forcing for a given type and concentration of another greenhouse gas

94
Q

Is equivalent co2 larger of smaller than actual co2 ppm

A

Larger

Usually by 25-30%

95
Q

If we eliminated all anthropogenic aerosols, how would it affect to co2 concentrations?

A

It would increase them almost instsntly

Believed that snthroopgenic aerosol cooling effect is offset by non-co2 g gases

96
Q

Why do they recommend reducing blsck soot?

A

Its the only aerosol that significantly warms the climate by directly absorbing solar energh

Removing soot reduces radiative forcing directly

97
Q

What are the two bad properties of halocsrbons (hfcs)

A

Destroys atmospheric ozone by releasing chlorine

Strong greenhuose gas - 5000 times stronger than co2, long lifetime,

98
Q

Ground level ozone pollution is formed by what

A

Oxygen + volatile organic compounds + nitrous oxide (traffic exhaust + indutries) = react with sunlight = makes smog

Harmful to humans and plants

99
Q

Where does the carbon being released via fossil fuels go

A

Oceans and land + most into the atmosphere

100
Q

What are three forms of carbon storage?

A 
Inorganic carbon (co2 in oceans, atmos, valcanic vents)
Organic carbon (photosynthesis)
Carbon in rocks
101
Q

What is co2 residence time in the atmosphere/

A

4 years

102
Q

CO2 is nesrly uniformly mixed in the atmos since global atmos mixing occurs on a time scale of less than year… however the anthropogenic carbon pulse lifetime in the total climate system is much longer… why?

A

Because its determined by the final burial rste of carbon into the ocean bottom, which is very small

103
Q

What is the difference between emissions and concentrations

A

Emissions is what were adding

Concdntrations is how much there is total

104
Q

What are two anthropogenic carbon dioxide sinks

A

Land biomass and oceans

105
Q

What are the sources and sinks of anthropogenic co2

A

Sources
Fossil fuels and land use (deforestation)

Sinks
Oceans, land biomass, stays in atmosphere

106
Q

What is gross primary productivity?

A

Photosynthesis removign atmospheric co2 — creating new biomass

107
Q

What does deforestation do to the csrbon budget?

A

Appears as a source because it reduces the removal of co2 from the atmos

108
Q

Explain the ocean biological carbon pump

A

Photosynthesis in surface waters - stores carbon as organic matter, reduces partisl pressure of surface ocean co2

Helps draw down carbon dioxide from atmosphere

109
Q

What is happening to the ph of the oceans as more co2 is drawn in

A

Becoming more acidic, affecting ecosystems

110
Q

Fresh water makes up 3% of all water on earth. 70% of thst fresh water is icecaps and glaciers and 30 % is ground water… what makes up that last 0.3% of fresh water?

A

Lakes and swamps and rivers

111
Q

What is runoff?

A

Precipitation - evapotranspiration

112
Q

In the global annual average the total amount of evaporation of water and ice from the earth’s surfacd must equal the total what?

A

Precipitation

113
Q

What makes the oceans locally saltier? What makes them locally fresher?

A

Saltier - evaporation greater than precipitation - drought can occur and ocean becomes saltier

Fresher - evaporation less than precipitation - excess water runoff returns to oceans

114
Q

What is the residency time of water vapour in the atmos? How does the effect tropospheric aerosols and pollution?

A

One week

Pollution and tropospheric aerosols wash out with rain - so their residency time is also about a week

115
Q

Why does you skin feel cold after coming out from swimming in a lake? How would a windy day affect this?

A

Cold water on skin evaporates
This requires energy/latent heat
Latent heat is extracted from your body/skin
Wind = low humidity = evaporation rate is faster and cooling is faster

116
Q

In the phases of water, what processes require latent heat input? What processes release latent heat?

A

Require - evaporation and sublimation of ice (from ice to vapour)

Release - condensation and deposition (vapour to ice)

117
Q

What drives the hydrological cycle?

A

The atmosphere has a net radiation deficit and the surface has a net radiation surplus

118
Q

When does the latent heat get released back into the atmosphere as sensible hest in the hydrological cycle?

A

When it rains, the latent heat gets released as sensible heat

119
Q

In the atmosphere how is the latent hest being transferred?

A

Going from evaporation to condensation sites

Energy from surface up to the higher latitude in the atmosphere

120
Q

What is the saturation water vapour

A

Max amount of water vapour at equilibrium

It increases with temperature

121
Q

What is the relative humidity?

A

Ratio of actual amount of water vapour to the saturation amount of water vapour

122
Q

What happens when the relative humidity is 100%

A

The air parcel is being cooled when its being lifted into the atmosphere and forms a cloud

123
Q

What happens to the relative humidity as the air parcel cools? (Hint; air that goes up is make]ing rainy clouds, sir thst going down is cloud-free and sunny)

A

When it coolsmas it moves upward, the amount of water vapour stays the same

As temp decreases the saturated amount lg water vapour decreases

As a result, the relative humidity increases, and once it reaches 100% the water vapour condenses and makes a CLOUD

124
Q

What causes rain?

A

Air parcel rises, expands to match air pressure which gets smaller w height

Volume increases and parcel does work against surrounding sir which uses internal energy - parcel starts to cool

Relative humidity increases as parcel cools - at 100% makes a cloud because parcel is saturated with water vapour

Eventually gets cold enough, ice crystals forms and grow and fall out of the cloud, melt and rain to the ground!!!

125
Q

What 2 things is the rainfall rate proportional to?

A

Amount of water vapour being lifted

Strength of the upward motion in the cloud

126
Q

Most desert are located under what

A

The descending branch of the hadley cells

Warms air and evaporates the clouds

127
Q

High precipitation occurs where

A

Near equator with the ascending branch of the hadley cell

Warm moist air being lifted upwards

128
Q

What are some climate vegetation interactions

A

Vegetation and albedo

  • dense forest = dark = absorb sun
  • pasture = light = reflects

Transpiration increases water vapour in atmos

129
Q

What are aerosols

A

Tiny particles

0.01-10 um

130
Q

What are primary aerosols? What are secondary aerosols?

A

Primary = crested st earth’s surface and lofted by wind

Secondary = made by gas to particle chemical reactions in atmosphere

131
Q

What is the lifetime of aerosols?

A

Only about a week in troposphere

132
Q

By burning fossil fuels, how are aerosols created?

A

Incomplete combustion

133
Q

Why are aerosols important?

A

Reflect sunlight back to space(cooling)

Act as nuclei centre for cloud droplets and ice crystals

Health concern + air quality

Acid rain

Volcanic eruptions - aerosols in strato

Reduce visibility (planes can’t see shit)

134
Q

What is the direct aerosol effect?

A

Aerosols reflect sunlight to space

Exception - soot absorbs sunlight

135
Q

More aerosols mean more cloud droplets because they can act at nuclei for them. How does this affect the cloud properties and the climate?

A

Clouds are brighter and reflect more sun

136
Q

What is the indirect aerosol effect (cooling effect)

A

Aerosols make clouds brighter so they reflect more sun back to space

They have smaller droplets making it harder for the cloud to rain and therefore they last longer in the atmosphere

137
Q

How long can volcanic aerosols that reach the stratosphere reside there? Why?

A

1-2 years

Lacks clouds and rainfall to remove them

138
Q

What is a positive feedback?

A

Amplifies the original change, can be negative or positive amplification / increase or decrease

139
Q

What is a negative feedback

A

Reduces the magnitude lf the original change, regardless of whether the change was an increase or a decrease

140
Q

Why is the water vapour feedback large and positive?

A

Global air temp increases bc co2 concentrations increase, water vapour increases in atmos, increased greenhouse gas warming from water vapour

Amplified

141
Q

Why do the nighttime temps in a desert get very cold even though it was very hot during the day

A

Amount of atmos water vapour in desert is low

The blanket is thinner, penetration depth is longer, more terrestrial radiation from the ground going upward and cooling at the ground

142
Q

Do high clouds warm or cool the earth?

A

Warm the earth

Transmit most solar but block warm infrared from the surface and emits cold infrared to space

143
Q

Do low clouds warm or cool the earth?

A

Cool the earth

Reflect most solar back to space and emit warm thermal infrared radiation

144
Q

What type of cirrus clouds show a positive feedback? What type show a negative feedback?

A

more thin cirrus clouds - warming (thin wispy clouds)

Less thin cirrus clouds - negative feedback

145
Q

Cumulus clouds - positive and negative feedback

A

More cumulus clouds - cooling - negative feedback

Less cumulus clouds - warming
Positive feedback

146
Q

What is an uncertainty with clouds and climate change?

A

Whether it will be a positive or negative feedback

If its cirrus clouds (more infrared blocked) or less total clouds (more solar reaching surface) then it will be positive feedback — more warming

If its low clouds (increase solar albedo) and less thin cirrus clouds - negative feedback, cooling

147
Q

The ice albedo and temperature feedback - positive or negative? Explain

A

Positive

Warming - increased open water in summer, thinner ice, less snowmcover - more shortwave solar absorbed into system - more warming

148
Q

Large areas in arctic ocean are currently dark… this means

A

Absorbing solar radiation - positive feedback

149
Q

Vegetation has some positive and negative feedbacks. Give examples or each

A

Positive
Albedo; higher temp - more veg - darker surfsce - more absorption- higher temp
Moisture supply; more veg - more evapotranspiration - more water vapour - more rain - more veg

Negative
Carbon budget; more co2 - more veg - more photosynthesis - removal of co2

150
Q

About 1/3 of all land has been converted to what… how does the effect climate

A

Cropland or pasture

Surface albedo, soil moisture and carbon fluxes

151
Q

What are some possible feedback in the biosphere that we need to know to predict future co2?

A 
Plankton multiplier
Soil microbial activity
Biosphere dieback 
Release of stored methane
(All positive)

Carbon dioxide fertilization (negative)

152
Q

Methane temperature feedback - positive or negative? Explain

A

Positive

Temperature goes up - permafrost thaws - co2 and methane release into atmosphere - temp warms

153
Q

The climate consists of 5 interacting components… what are they

A 
Atmosphere
Hydrosphere
Cryosphere
Land surface
Biosphere
154
Q

What is the main difference between weather and climate forecasting?

A

Weather forecast = predict future atmosphere state at a particular time and location, minimizing difference between predicted and actual weather at that place and time

Climate = we don’t care about weather at a particular time, but care about the average predictions and the extended time period

155
Q

How is weather forecasting done?

A

Computers numerically solve atmospheric equations or motion

156
Q

What are the 3 equations that have to be solved to predict weather? What equation predicts what?

A

Momentum - predict winds

Energy - predict temp

Continuity - density of air and water

157
Q

Why aren’t the weather forecasts perfect?

A

Gaps and errors in measurement

Limited spatial resolution of computer model
- need faster computers to improve models

Non linearity of system - limits range of weather predictions to weeks, not an issue for climate models though

158
Q

How do we model complex sub-grid processes like clouds?

A

Approximate the small scale effects, measure on a small scale

159
Q

What are the steps in running a global climate model (global circulation model - GMC)

A
  1. Specify input - choose boundary based on known changes of solar, co2, ice sheets, mountains, continent position
  2. Run model simulation of ocean and atmos - physical laws or radiation + circulation
  3. Analyze climate output
  4. Compare - data from earth’s history
160
Q

What are some main difference in climate vs weather models in terms of resolution, simulation time, vegetation, oceans

A 
Climate
Resolution = 100km
Oceans = full air-sea interaction. Ocean dynamics
Time - >30 years
Veg = highly interactive
Weather
Resolution = 10km
Oceans = fixed sea surface temp
Time = 2-14 days
Vegetation = fixed or ignored
161
Q

Climate models are now so sophisticated that they are now called…

A

Earth systems models

162
Q

Testing the climate models ability to predict 20th century temps is part of the validation procedure. Models tend to do a good job of predicting 20th century climate but it can be right for the wrong reasons… what are some future improvements for climate models

A 
Faster computers
higher spatial resolution
Improve parameters around some processes
More observational data
More inter-model comparisons from groups around the world
163
Q

How were climate models used to understand current climate change

A

Cooling of sea surface temp in North Atlantic may be caused by anthropogenic aerosols from europe, helped weaken African monsoon

Also weakened monsoon circulation and shifted inter-tropical convergencezone

164
Q

What equilibrium climate sensitivity?

A

Equilibrium / final steady state change in the global mean surface temp following doubling of pre-industrial co2

165
Q

What is the transient climate response

A

20 year global mean surface temp chg after 70 years of carbon dioxide increasing at 1% per year compounded
- results in a doubling of co2 in 70 years

166
Q

What are some positive feedbacks in the earth’s climate system

A

Water vapour
Ice albedo
Clouds

167
Q

the equilibrium climate sensitivity would only be about 1.2 deg if we just consider the effects of a doubling co2 concentration. Why is actually 3 deg?

A

Because of the positive feedbacks

168
Q

What does a low sensitivity mean/ what about a high sensitivity?

A

Low = low change, climate change will be much easier to deal with

High = climate change will be detrimental and cost to adapt is high

169
Q

Whatis the precautionary principle

A

Principle in environmental law

Dictates that we should plan for a higher value, don’t ignore the high value rven though you have an average

Insurance policy

170
Q

Why do we still have some uncertainty in the model derived equilibrium climate sensitivity?

A

Because the feedbacks have significant uncertsinties

Especially clouds and oceans

171
Q

What is the transient climate response

A

Amount of warming expected in 70 years for a doubling of co2

172
Q

What is the range for the transient climate reponse

A

1-2.5 deg in the next 70 years

173
Q

Climate sensitivity is designed to look at graudal average trends in climate induced by gradual change in radiative forcing. It does not account for…

A

Rapid changes

Unstable tipping points

174
Q

Who makes assessment reports roughly every 6-8 years to update climate forecasts, using w0 global climate models from various centres around the world and creates model predictions to project climate change in the next 100 years…

A

Ipcc

Intergovernmental panel on climate change

175
Q

What are representative concentration pathways

A

Four future radiative forcing pathways developed for the climate odeling cmomunity as a basis for modelling experiments

I.e models for climate scientists to follow so that the reports are comparable

176
Q

How are rcp’s set up?

A

Final radiative forcing values of 2.6-8.5 With co2 concentrations and the effects/pathway of each value

177
Q

What is our current radiative forcing value (2011)? What is the value is co2 doubles?

A
  1. 3 W / m2

3. 8 W / m2

178
Q

Which rcp pathway are we currently following?

A

Rcp 8.5 - this is the worst one :)

179
Q

The last 542 million years was the..

A

Phanerozoic

180
Q

What was the main controller of temperature in the phanerozoic?

A

Co2

181
Q

The earth’s crust is divided into…

A

Plates that move in response to convection in the mantle

182
Q

Explaine the relationship between volcanism and rock weathering

A

If rock weathering sink of co2 exceeds volcanism’s supply/source of co2

Atmos co2 decreases, climate cools, vice versa

183
Q

What 3 things do tectonics control

A

Volcanism

Continental drift

Orogenesis (mountain making, continental plates collide)

184
Q

Is weathering a negative or positive feedback on tectonic forcing

A

Negative feedback

Prevents extreme temps by stabilizing amount of co2

System adjust to reduce initial change

185
Q

What ended after an asteroid hit 65 million years ago near the yucatan peninsula

A

Cretaceous period

186
Q

What are the 6 major extinction events that happened during the Phanerozoic in order

Often-sit down, perhaps their-joints creak, agonizingly

A

Ordovician - silurian (glaciation)

Late Devonian (dust, volcanoes)

Permian (largest mass extinction)

Triassic/jurassic (floods)

Cretaceous/ palocene (k-t event - asteroid)

Anthropocene - current day, caused by humans

187
Q

Earth has been gradually cooling over the last 50 million years, how do we know this?

A

Temps derived from oxygen isotope analysis of marine organisms buried in the sea floor

188
Q

Why did the global climate cool over the last 50 million years? (3 things)

A

Sea floor spreading rate decreased, slowing the rate of co2 input

Weathering caused faster removal of co2, formation of Himalayas

Poleward ocean heat transport reduced and deep water formation shifts to high latitudes

189
Q

What formed the Himalayas? Effect on climate?

A

Collision of indian subcontinent with asia

Exposed rock for chemical weathering
Removed co2 and cooled climate

190
Q

What allowed Antarctica to cool and start growing ice sheets?

A

Opening of drake’s passage helped isolate Antarctica from meridional (north-south) heat transport

191
Q

We are in a long glaciation epoch although currently we are in an interglacial period called the..

A

Holocene

192
Q

How do we deduce recent psst climates?

A

Tree rings
Ice core drilling
Lake sediment

193
Q

Atmospheric co2 lowered from the pre-industrial holocene concentration of 280 ppm to 190ppm during the glacial maximum about 20,000 years ago…mwhere did this 90 ppm of co2 go?

A

Deep ocean

194
Q

Glaciation is initiated by the earth’s orbit which is controlled by attractions between the earth, moon, sun and other planets (mostly Jupiter). What are the three orbital variations

A
  1. Earth’s tilt varies over 41,000 year - solar input varies in high latitude
  2. Orbit around sun varies every 100,000 years - seasons
  3. Position of solstices
195
Q

What are milankovitch cycles? (3 variations do to with earth’s orbit)

A

Earth’s orbit around the sun

Tilt of earth

Soltices

196
Q

How can glaciation start

A

Summer solar energy needs to be weak enough to not melt all the previous winter’s snow

Ice sheets need to form on land

SUMMER SOLAR ENERGY AT 65 DEG NORTH LATITUDE

197
Q

What is the key variable to predict the growing ice sheets

A

SUMMER SOLAR ENERGY AT 65 DEG NORTH LATITUDE

198
Q

What was the period of deglaciation cooling that happened over 12,000-10,700 years ago

A

Younger dryas

199
Q

What is some evidence for the younger dryas cold period

A

Southward re-advancement of polar water in the north atlantic to 45 deg north

Scotland reverted to arctic vegetation

Insect fossil in Britain indicated cooler temps

200
Q

What caused the younger dryas

A

Change in melt-water flow in north america during deglaciation

Drainage direction of north American ice sheet changed from southward to gulf of Mexico to northward into the hudson bay + arctic ocean

Brought pulse of fresh water, cutting off deep water formation and cooling the region

201
Q

Why were the monsoons much stronger 10,000 years ago?

A

Because sun was much closer to earth

202
Q

When did the transition for hunsting-gathering to farming start? Why?

A

About 10,000 yesrs ago

Monsoons much stronger because Northern hem summers much warmer and wetter

203
Q

About 5000 years ago, many civilizations started to collapse (china, indus, nile, peru, maya, and some others)… why?

A

Drought

204
Q

During a little ice age, about 1400-190p in europe, what sun spots occured?

A

Maunder sunspot minimum

Sporer sunspot minimum

205
Q

What are some possible explanations for the little ice age that happened in europe and destroyed many villages and farmhouses in the alps

A

Change in ocean circulation- thermohaline circulation may have slowed down

Strong volcanoes putting aerosols in stratosphere, reducing solar radiation reaching surface

206
Q

What interglacial period happened about 120,000 yesrs ago, had sea levels about 4-6 m higher than today’s and a smaller greenland ice sheet? Its also a potential indicator for what our future may look like in the next hundreds of years

A

Eemian

207
Q

The eemian is believed to have been only 1 deg warmer than today and sea level was 4 m higher at its maximum. Why?

A

May be because the collapse if west Antarctica ice sheet caused rapid sea level rise without an accompanying warming

208
Q

What period is an analog for our future in next 1000 years

A

Mid-pliocene warm period, 3.3 million years ago

209
Q

What period had temps 2-3 deg highter, sea level 25 m higher, Greenland ice sheets much smaller

A

Mid pliocene

210
Q

The global cooling that occurred towards the end of the pliocene may be responsible for what shift in vegetation

A

Forests to grasslands and savannas

211
Q

Why is the pliocene s]a useful period to use as an analog

A

Continental positions were basically the same

Ocean circulation and biota were similar

Give us an idea what to expect with a warmer equilibrium established on earth with co2 over 400 ppm

212
Q

What were the pliocene biomes like

A

Northward shift to temperate and boreal vegetation zones, expansion of tropical savannahs

High arctic covered in boreal forests, glaciation in canada not happening yet

213
Q

The mid pliocene was around 400 ppm, 2-3 deg warmer, sea level was 25 m higher suggesting reductions in contniental ice sheets and warmer ocean temps… why is this important to us now

A

Its a window into out future, what to expect in the long-term

214
Q

What period is an analog for rapid warming?

A

Paleocene-eocene thermal maximum (PETM)

215
Q

In which period did global temp rise by 6-8 deg over a 20,000 year period , where many benthic forminifera a d terrestrial mammals wen’t extinct, but numerous modern mammalian order emerged?

A

Petm

216
Q

What were the 2 observations that indicated a massive release of carbon at the petm?

A

Large global negative carbon isotope excursion

Dissolution of deep ocean carbonates

217
Q

What was it likely that the negative shift in carbon isotope was likely organic carbon

A

Organisms discriminate againt carbon 13 during photosynthesis

218
Q

What limits the petm analog?

A

Ice sheets and ocean circulation quite different as well as continental positions

Climate Change (2 decks)

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