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A Level Geography (OCR) > ELSS (Topic 2) > Flashcards

ELSS (Topic 2) Flashcards

1
Q

What % of Earth’s surface is oceans?

A

71%

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2
Q

How do oceans moderate Earth’s environment? (3 ideas)

A
  1. Absorbing heat, storing it and releasing it slowly
  2. Clouds reflect 1/5 of solar radiation- lowers temperature (albedo effect)
  3. Water vapour absorbs long-wave radiation from the Earth- helps maintain global temps 15*C higher than would be
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3
Q

How do flora use water? (4 ideas)

A
  1. Manufacture own food so need water for: photosynthesis (combining CO2, sunlight & water = glucose and starches); respiration (converts glucose to energy through reaction with oxygen- release CO2 & water)
  2. Maintain rigidity- wilt when run out of water
  3. Transport mineral nutrients from the soil
  4. Cooling- transpiration of water from leaf surface cools plants by evaporation
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4
Q

How do fauna use water? (2 ideas)

A
  1. Water = the medium for all chemical reactions- i.e. circulation of oxygen and nutrients
  2. Evaporative cooling achieved through panting
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5
Q

How do humans use water? (3 ideas)

A
  1. Water = the medium for all chemical reactions- i.e. circulation of oxygen and nutrients
  2. Cooling- sweating
  3. Economic activity- generate electricity, irrigate crops, provide recreational facilities, satisfy public demand (drinking water, sewage disposal), industry (food manufacturing, brewing, steel making)
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6
Q

How is carbon stored? (5 ideas)

A
  1. Carbonate rocks (limestone)
  2. Sea floor sediments
  3. Ocean water (as dissolved CO2)
  4. Atmosphere (CO2 gas)
  5. Biosphere
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7
Q

How is life carbon based?

A

Built on large molecules of carbon- proteins, carbohydrates, nucleic acids

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8
Q

How can carbon be used as an economic resource? (3 ideas)

A
  1. Fossil fuels (coal, oil, natural gas) power the global economy
  2. Oil is used as a raw material in manufacturing of products (from plastics to paint and synthetic fabrics)
  3. Agricultural crops and forest trees store large amounts of carbon available for human use (i.e. food, timber, paper, textiles etc)
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9
Q

What is the atmosphere?

A
  • Envelope of gases surrounding the planet
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10
Q

What is the cryosphere?

A
  • Frozen part of the Earth’s surface
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11
Q

What is the lithosphere?

A

Rigid outer part of the Earth (upper mantle and crust)- divided into tectonic plates

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12
Q

What is hydrosphere?

A
  • All the water on the Earth’s surface
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13
Q

What is the biosphere?

A
  • Space at the Earth’s surface and within atmosphere occupied by living organisms
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14
Q

What is the pedosphere?

A
  • Soil layer of Earth
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15
Q

At a global scale, what are the 3 main stores of the water cycle?

A
  1. Oceans (biggest store)
  2. Atmosphere (smallest store)
  3. Land
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16
Q

What are the main processes by which water moves between the 3 stores? (4 ideas)

A
  1. Precipitation
  2. Evapotranspiration
  3. Run-off
  4. Groundwater flow (horizontal movement of water within aquifers)
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17
Q

What is the long-term storage of carbon AND what % does it hold of all carbon on Earth?

A

Sedimentary rocks

99.9%

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18
Q

What stores does the carbon in circulation move between? (4 ideas)

A
  1. Atmosphere
  2. Oceans
  3. Soil
  4. Biosphere
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19
Q

What are the main processes by which circling carbon moves between the stores? (4)

A
  1. Photosynthesis (atmosphere to terrestrial biomass)
  2. Respiration (terrestrial biomass to atmosphere)
  3. Oxidation (human activity- combustion to atmosphere; decomposition- terrestrial biomass to atmosphere; soil to atmosphere)
  4. Weathering (sedimentary rocks to atmosphere)
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20
Q

What is a large-scale, infrequent event which moves a large amount of carbon from sedimentary rock to the atmosphere?

A

Volcanic eruption

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21
Q

Define systems

A

Systems are groups of objects and the relationships that bind the objects together

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22
Q

What is a closed system?

A

A system with inputs and outputs of energy, but without any movement of materials across system boundaries

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23
Q

What is an open system?

A

A type of system whose boundaries are open to both inputs and outputs of energy and matter

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24
Q

What type of system are the water and carbon cycles at a global scale?

A

Closed systems

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25
Q

Why are the global water and carbon cycles closed?

A

Only energy (and not matter) can cross the boundaries of the global water and carbon cycles

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26
Q

What energy drives the global water and carbon cycles?

A

Sun’s energy (external to the Earth)

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27
Q

What type of system are smaller scale water and carbon cycles?

A

Open systems

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28
Q

Examples of smaller scale cycles (2 ideas)

A
  1. Drainage basins
  2. Forest ecosystem
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29
Q

Why can smaller scale cycles be considered open?

A

Materials as well as Sun’s energy can cross system boundaries

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30
Q

What % of global water is stored in oceans?

A

97%

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31
Q

What % of global water is stored in polar ice and glaciers?

A

2%

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32
Q

What % of global water is stored as groundwater (aquifers)?

A

0.7%

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33
Q

What % of global water is stored in atmosphere?

A

0.001%

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34
Q

How much water is frozen in the ice caps of Antarctica and Greenland?

A

3/4

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35
Q

How much fresh water is stored below ground in permeable rocks?

A

Only 1/5 of all fresh water

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36
Q

What can explain the fact that only a minute fraction of water is found in the atmosphere?

A

Rapid flux of water (into and out of atmosphere)

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37
Q

What is the avg. residence time of a water molecule in the atmosphere?

A

9 days

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38
Q

How much water does the global water cycle budget circulate per year (estimate) as inputs and outputs between the principal water stores?

A

505,000km3

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39
Q

What are the main inputs and outputs of the water cycle? (7 ideas)

A
  1. Water vapour evaporated from oceans, soils, lakes and rivers
  2. Vapour transpired through the leaves of plants
  3. Precipitation (rain, snow, hail etc)
  4. Condensation (fog)
  5. Ice sheets, snowfields, glaciers release water by ablation (melting & sublimation)
  6. Run-off (drains precipitation & meltwater from land into rivers)- BUT some continental drylands drain to inland basins (i.e. S-W USA)
  7. After infiltrating soil, water may percolate (gravity) into permeable rocks/aquifers- eventually reaches surface (springs & seepages- contribute to run-off)
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40
Q

What is the biggest stores of carbon AND how much (bn tonnes)?

A

Sedimentary (carbonate) rocks (i.e. limestone, chalk) and deep ocean sediments- 60,000 - 100,000,000

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41
Q

Where is most of the carbon not stored in rocks & sediment found AND how much (bn tonnes)?

A

Oceans (as dissolved CO2)- 38,700

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42
Q

What are the smallest stores of carbon AND how much (bn tonnes)? (3 ideas)

A
  1. Atmosphere (600)
  2. Land plants (560)
  3. Soils/peat (2,300)
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43
Q

Why are these smaller stores of carbon still crucial?

A

Represent most of the carbon in circulation at any one time

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44
Q

What are the 2 different strands of the carbon cycle?

A
  1. Fast cycle
  2. Slow cycle
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45
Q

How long is carbon stored in rocks, sea-floor sediments and fossil fuels locked away for?

A

Millions of years

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46
Q

What is the total amount of carbon in circulation by the slow cycle?

A

Between 10 - 100 million tonnes a year

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47
Q

How does the slow carbon cycle work? (3 steps)

A
  1. CO2 diffuses from atmosphere to oceans- marine organisms (i.e. clams, corals) make their shells & skeletons by fixing dissolved carbon with calcium = calcium carbonate (CaCO3)
  2. Organisms die, sink to ocean floor
  3. Accumulate and over millions of years, heat and pressure convert them to carbon-rich sedimentary rocks
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48
Q

What is the typical residence time for carbon held in rocks?

A

150 million years

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49
Q

How is carbon held in rocks released? (2 ideas)

A
  1. Volcanic eruptions- carbon-rich sedimentary rocks = vented to atmosphere (subduction)
  2. Rocks exposed at surface (tectonic movements & erosion) = attacked by chemical weathering- i.e. carbonation attacks carbonate minerals in rocks, releasing CO2 to atmosphere, and in dissolved form to streams, rivers and oceans
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50
Q

How do carbonaceous rocks form AND examples?

A

On land, partly decomposed organic material buried beneath younger sediments

e.g. coal, lignite, oil and natural gas (act as carbon sinks that endure for millions of years)

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51
Q

Which stores does carbon circulate most rapidly between in the fast cycle? (4 ideas)

A
  1. Atmosphere
  2. Oceans
  3. Living organisms (biosphere)
  4. Soils
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52
Q

How much quicker are the transfers in the fast cycle than in the slow cycle?

A

10 - 1,000 x faster

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53
Q

What are the key components of the fast cycle? (2 ideas)

A
  1. Land plants
  2. Microscopic phytoplankton in the oceans
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54
Q

How does carbon cycle in the fast cycle? (3 ideas)

A
  1. Photosynthesis- CO2 absorbed (land plants & phytoplankton- combine it with water to make carbohydrates e.g. sugars/glucose)
  2. Decomposition of dead organic matter by microbial activity- returns CO2 to atmosphere
  3. Atmospheric CO2 dissolves in ocean surface waters while the oceans ventilate CO2 back to atmosphere- through exchange, individual carbon atoms = stored (natural sequestration) in the oceans
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55
Q

How long do individual carbon atoms remain in the oceans for?

A

Avg. 350 years

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56
Q

What is dynamic equilibrium?

A

A system displaying unrepeated average states throughout time

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57
Q

What happens in the short-term to inputs, outputs and stores of the water and carbon cycles?

A

They will fluctuate from year to year

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58
Q

What happens in the long-term to flows and stores of the water and carbon cycle?

A

Usually maintain a balance, allowing a system to retain its stability

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59
Q

What do negative feedback loops within systems do?

A

Restore balance

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60
Q

Example of negative loop in a drainage basin (3 steps)

A
  1. Heavy rainfall increases water stores in aquifers
  2. Causes a raise to the water table, increasing flow from springs
  3. Water table reverts to normal level
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61
Q

Example of negative feedback loop in the carbon cycle (3 steps)

A
  1. Burning fossil fuels increases atmospheric CO2
  2. At same time, stimulates photosynthesis (plant growth)
  3. Remove excess CO2 from atmosphere
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62
Q

What is urbanisation?

A

The conversion of land use from rural to urban (i.e. farmland and woodland replaced by housing, offices, factories and roads)

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63
Q

How does urbanisation affect the stores and flows in the water cycle? (4)

A
  1. Increased impermeable surfaces, allowing for little to no infiltration (store), increasing run-off (flow)
  2. Urban areas have drainage systems designed to remove surface water rapidly (i.e. pitched roofs, gutters, sewage systems), decreased lag time, increasing flood risk
  3. Removal of vegetation, decreased storage (interception & absorption), increased run-off (flow), decreased lag time so increased flood risk
  4. Encroaches on flood plains (natural store of water), reducing water storage capacity in drainage basins, increasing river flow and flood risk
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64
Q

How does urbanisation affect the stores and flows in the carbon cycle? (2)

A
  1. Increased emission of CO2 (cars, factories etc) leading to increased atmospheric store
  2. Decreased vegetation, decreased photosynthesis, decreased storage of CO2 in biosphere
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65
Q

How does farming affect the stores and flows in the water cycle? (3)

A
  1. Tractors and heavy machinery compact soil (impermeable), increasing run-off and river discharge
  2. Irrigation systems take water from rivers & groundwater- most is lost to evaporation, decreasing ground storage & river storage
  3. Ploughed furrows act as drainage channels, accelerating run-off and soil erosion
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66
Q

How does farming affect the stores and flows in the carbon cycle? (3)

A
  1. Clearance of forest for farming reduces carbon storage in above and below ground biomass
  2. Ploughing releases carbon to atmosphere, creating a carbon source
  3. Soil erosion most apparent when crops have been lifted and soils have little protective cover, releasing CO2
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67
Q

How does forestry affect the stores and flows in the water cycle? (4)

A
  1. Higher rates of interception- e.g. conifers’ needle-like structure, ever green and high density
  2. Increased evaporation- evaporated off leaf surfaces after interception
  3. Reduced run-off & discharge- high interception & evaporation and absorption of water by roots
  4. Transpiration rates increased- e.g. Sitka spruce in the Pennines around 350mm/year of rainfall equivalent
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68
Q

How does forestry affect the stores and flows in the carbon cycle? (3)

A
  1. Increased store of carbon- e.g. mature forest trees contain on avg. 170-200 tones C/ha (10x higher than grassland, 20x higher than heathland)
  2. Increased carbon store in soil- in England, measurements of forest soil carbon around 500 tonnes C/ha
  3. Sequester carbon from atmosphere BUT only active carbon sink for first 100 years- forestry plantations rotation of 80-100 years to mitigate
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69
Q

What is an aquifer?

A

A layer of permeable water-bearing rock that can contain or transmit water (e.g. chalk)

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70
Q

What is abstraction?

A

The process of taking water out of the ground, temporarily or permanently

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71
Q

What is the water table?

A

The level in the ground below which the ground is saturated

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72
Q

What is groundwater?

A

Water that is held within the ground in the soil or in pores (spaces) in the rock

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73
Q

What is recharge?

A

The replenishment of an aquifer by absorbing water from precipitation

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74
Q

What is a syncline?

A
  • A downward trough (or bowl) in the land which results in the land sloping upwards
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75
Q

What is artesian pressure?

A
  • This is created by the layers of impermeable rock, effectively squeezing the water in the aquifer
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76
Q

What is an artesian basin?

A
  • This is where an aquifer is trapped between 2 layers of impermeable rock, creating pressure
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77
Q

What is an artesian well?

A
  • This is the type of well that naturally flow up to the surface, due to the pressure its under
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78
Q

Why is water extracted from the surface and the ground?

A
  • To meet public, agricultural and industrial demand
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79
Q

What area does the river Kennet drain?

A

An area of around 1,200km(2) in Wiltshire and Berkshire

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80
Q

What does the upper catchment of the Kennet mainly comprise? What is significant about this?

A

Chalk (highly permeable) so groundwater contributes most of the Kennet’s flow

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81
Q

What animals does the Kennet support?

A

Atlantic salmon, brown trout, water voles, otters and white-clawed crayfish

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82
Q

What is the largest urban area that relies on the Kennet to meet public supply?

A

Swindon (220k)

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83
Q

What impact has extraction from the Kennet had on the regional water cycle? (4)

A
  1. Rates of extraction exceeded rates of recharge- falling water table has reduced flows in Kennet by 10-14%
  2. During 2003 drought, flows dell by 20% and in dry conditions of early 1990s by up to 40%
  3. Lower floods have reduced flooding and temporary areas of standing water and wetlands on the Kennet’s floodplain (Marlborough-Hungerford)
  4. Lower groundwater levels have caused springs and seepages to dry up and reduced incidence of saturated overland flow on the chalk hills of the Marlborough Downs
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84
Q

What is the normal water table cycle in Southern England?

A
  • Water table falls from (March to September) as rising temperatures increase evapotranspiration losses
  • Recharge resumes in the late autumn
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85
Q

What is the potentiometric surface?

A

An imaginary surface that defines the theoretical level to which water would rise in a confined aquifer

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86
Q

What is London located at the centre of?

A

A synclinal structure which forms an artesian basin

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87
Q

What is groundwater in the chalk aquifer trapped between?

A

London clay & Gault clay (impermeable)

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88
Q

Where does rainwater enter the chalk aquifer?

A

Where it outcrops on the edge of the basin in the North Downs and Chilterns

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89
Q

When was the London groundwater overexploited? What was the result?

A

C19th & first half of C20th

Caused a drastic fall in the water table (C. London fell by nearly 90m)

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90
Q

… but by early 1990s what rate was London’s water table rising at? And so what?

A

Rate of 3m/year

Began to threaten buildings and underground tunnels

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91
Q

What has Thames Water been granted since 1992?

A

Abstraction licences to slow the rise of the water table (which is now stable)

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92
Q

What are the main fossil fuels that have driven global industrialisation and urbanisation?

A

Coal, oil and natural gas

93
Q

In 2019, what % of global energy consumption did fossil fuels account for?

A

84

94
Q

When did the increasing combustion of fossil fuels begin?

A

Industrial Revolution (1760)

95
Q

How much CO2 does fossil fuel consumption release to the atmosphere anually?

A

10bn tonnes, increasing atmospheric CO2 concentration by over 1 ppm (parts per million)

96
Q

Since 1750, what is it estimated human emissions of CO2 are? How much of this is by the burning of fossil fuels?

A

Nearly 2,000 GT (3/4 form burning of fossil fuels)

97
Q

What was the CO2 level in the atmosphere in 2021?

A

415 ppm (the highest for at least 800,000 years)

98
Q

What would atmospheric CO2 concentrations exceed without increased absorption of anthropogenic carbon by the oceans and biosphere?

A

500 ppm

99
Q

What is one possible solution to the problem of present-day global warming?

A

To capture and store CO2 released by power plants and industry

100
Q

What is carbon capture and storage (CCS)?

A

The removal of CO2 from emissions by thermal power stations and its storage in disused oil and gas wells underground

101
Q

What are the three stages to CCS?

A
  1. CO2 is separated from power station emissions
  2. CO2 is then compressed and transported by pipeline to storage areas
  3. It is injected into porous rocks deep underground where it is stored permanently
102
Q

What does CCS have the potential to reduce USA emissions from coal and gas-fired power stations by?

A

80-90%

103
Q

What is the Drax project in North Yorkshire? What is the plan?

A

Designed to capture 2 million tonnes of CO2 per year (commenced operation 2019)

Carbon transported by pipeline by pipeline to the North Sea and stored in depleted gas reservoirs

104
Q

What economic and geological factors limit CCS’ effectiveness? (3)

A
  1. Involves big capital costs- e.g. the Drax and Peterhead projects will cost at least £1bn
  2. Uses large amounts of energy- typically 20% of a power plant’s output is needed to separate the CO2 and compress it
  3. Requires storage reservoirs with specific geological conditions- i.e. porous rocks overlain by impermeable strata
105
Q

What is feedback in a system?

A

An automatic response to changes which disturb a system’s balance or equilibrium

106
Q

What makes positive feedback occur?

A

When an initial change causes further change (‘snowball’ effect)

107
Q

What does negative feedback do?

A

It counters system change and restores equilibrium

108
Q

What is the tipping point?

A

The critical point or threshold which if passed leads to irreversible change, e.g. the moment when summer sea ice in the Arctic disappears, which would alter the Atlantic thermohaline circulation

109
Q

What is equilibrium?

A

A long-term balance between inputs and outputs in a system

110
Q

What is dynamic equilibrium?

A

A system constantly changing and working to have that balance- shift between the outputs and inputs to try and find that balance

111
Q

Example of a positive feedback loop in the water cycle (4)

A
  1. Increased temperatures
  2. Higher rates of evaporation
  3. Atmosphere holds more water vapour (GHG)
  4. Enhanced greenhouse effect (increased absorption of solar radiation from the Sun)
112
Q

Example of a negative feedback loop in the water cycle (5)

A
  1. Increased temperatures
  2. Higher rates of evaporation
  3. Increased convection
  4. Increased cloud cover
  5. Increased albedo effect (more solar radiation being reflected off the light surface of clouds)
113
Q

How do drainage basins maintain equilibrium in the long term?

A

Balance the inputs with outputs - precipitation is balanced by outputs of evapotranspiration and run-off

114
Q

How do drainage basin systems respond to above average precipitation

A

Increasing river flow and evaporation; excess water recharges aquifers (increasing water storage in permeable rocks)

115
Q

What is drainage basin’s response an example of?

A
  • Negative feedback
116
Q

How do drainage basin systems respond to droughts?

A

Reducing run-off and evapotranspiration; as water table falls, springs and seepages dry up (help to conserve groundwater stores)

117
Q

How do trees (i.e. silver birch) respond to droughts?

A

Reducing transpiration losses by shedding some/all of its leaves (negative loop that restores the water balance and ensures the tree’s survival)

118
Q

Example of a positive feedback loop in the carbon cycle involving sea ice (5)

A
  1. Increased CO2 in atmosphere
  2. Enhanced greenhouse effect
  3. Sea ice melts (reducing albedo effect)
  4. More heat absorbed (increasing ocean temperatures)
  5. More sea ice melting (further albedo effect)
119
Q

Example of a positive feedback loop in the carbon cycle involving permafrost (5)

A
  1. Increased CO2/CH4 in atmosphere
  2. Enhanced greenhouse effect
  3. Permafrost melt (CO2/CH4 released)
  4. Further enhanced greenhouse effect (temperature increases)
  5. Further permafrost melting (CO2/CH4 released…)
120
Q

What diurnal changes occur in the water cycle? (2)

A
  1. Lower temperatures at night = reduce evapotranspiration.
  2. Convectional precipitation = daytime phenomenon (often afternoon when temps at max).
120
Q

What are the short-term changes to the cycles? (2)

A
  1. Seasonal - the changes that occur during the different seasons due to radiation differences and/or precipitation levels (time frame = over year).
  2. Diurnal - day and night changes (light and dark) this is measured over a 24 hour period.
121
Q

What diurnal changes occur in the carbon cycle? (3)

A
  1. Photosynthesis rates higher during daytime (CO2 from atmosphere to vegetation)
  2. Respiration rates higher during night (CO2 from vegetation to atmosphere).
  3. Decomposition rates higher during daytime (more CO2 to atmosphere) - lower during night.
122
Q

What is the main driver for seasonal change?

A

Solar radiation - tilt of the earth.

123
Q

How does solar radiation vary in the UK (southern England)? What is the result?

A

June - c800 W/m2

December - 150 W/m2

Result - evapotranspiration highest in summer months and lowest in winter = river flows in England normally at their lowest in late summer (80% precipitation lost to evapotranspiration).

124
Q

How are seasonal variations in the carbon cycle shown?

A

Month-to-month changes in the net primary productivity of vegetation (NPP)

125
Q

What seasonal variations occur in the water cycle (mid-high latitudes)? (2)

A
  1. Summer - more heat, river discharge lowest, soil moisture low = increased evapotranspiration.
  2. Winter = reverse.
126
Q

What seasonal variations occur in the water cycle (tropics/equator)? (2)

A
  1. Rainy season v drier season.
  2. Convectional rainfall all year round.

NB: insignificant - e.g. Amazon…

127
Q

What seasonal variations occur in the carbon cycle (mid-high latitudes)? (3)

A
  1. Summer - longer days (more sunlight), leaves on trees = increased photosynthesis.
  2. End of summer - increased leaf litter = decomposition.
  3. Winter - less leaves, shorter days = decreased photosynthesis.
128
Q

What seasonal variations occur in the carbon cycle (tropics/equator)?

A

Less rainfall = decrease in photosynthesis.

NB: insignificant - e.g. Amazon…

129
Q

Why do global CO2 concentration levels correspond to the northern hemisphere seasons? (2)

A

Larger amount of land mass = increased vegetation = higher photosynthesis (e.g. atmospheric CO2 levels fall by 2 ppm).

At end of summer, flow = reversed (natural decomposition releasing CO2 back to atmosphere).

130
Q

What causes algal blooms in the North Atlantic? When does it occur? (2)

A

Phytoplankton - stimulated into photosynthesis by rising water temperatures, more intense sunlight and the lengthening of the photoperiod.

Starts in March, peaks in mid-summer.

131
Q

How many glacial cycles have there been in the past 400,000 years?

A

4 major glacial cycles with cold glacials followed by warm inter-glacials.

132
Q

What is a glacial period?

A

Prolonged cold climatic phase lasting for tens of thousands of years and causing continental glaciation in middle and high latitudes.

133
Q

What is an inter-glacial period?

A

Period of climatic warming (lasting c.10,000 years) between glacials.

134
Q

How long has each glacial cycle tended to last?

A

100,000 years

135
Q

When was the last glacial period and relating conditions?

A

20,000 years ago - average annual temperatures in British Isles were 5*C lower than today (Scotland, Wales & most of Northern England and Ireland submerged by ice up to 1km thick).

136
Q

What happened in the warm inter-glacial periods? (2)

A

Temperatures - similar to those of today. However, on much longer time scales, global temperatures have been even more extreme.

Example - 250m years ago, avg. global temps reached 22C (at least 7-8C higher than today’s).

137
Q

What long-term changes occur in the water cycle (glacial)? (4)

A
  1. More water stored in ice sheets, glaciers and permafrost = sea level worldwide falls by 100-130 metres (ice sheets/glaciers expand to cover c1/3 continental land mass.
  2. Ice sheets advance Equator-wards destroying forest & grasslands = water stored in biosphere shrinks.
  3. Climate in tropics becomes drier - deserts and grasslands displace large areas of rainforest.
  4. Lower rates of evapotranspiration = reduce exchanges of water between the atmosphere and the oceans, biosphere and soils (slows the cycle).
138
Q

What long-term changes occur in the water cycle (inter-glacial)? (2)

A
  1. Ice sheets melt = higher sea levels = more evaporation.
  2. Higher temps = more plant growth & more evaporation due to more interception.

[NB: more water in the cycle.]

139
Q

What long-term changes occur in the carbon cycle (glacial)? (4)

A
  1. Reduction of CO2 in atmosphere (e.g. CO2 concentrations fall to about 180 ppm, while in warmer inter-glacial periods, 100 ppm higher)
  • a) changes in ocean circulation stimulate phytoplankton (die and sink to deep ocean).
  • b) Lower ocean temps = CO2 more soluble in surface waters.

2) Carbon pool in vegetation shrinks (ice sheets occupy large parts of continents - less vegetation (& lower temps/precipitation) = NPP will decline.

3) Carbon sequestered in permafrost.

[NB: overall slowing of carbon flux & smaller amounts of CO2 returned to atmosphere through decomposition.]

140
Q

What long-term changes occur in the carbon cycle (inter-glacial)? (3)

A
  1. Higher amount of vegetation = more CO2 stored in biosphere.
  2. Higher temps/precipitation levels = higher photosynthesis.
  3. Warmer/more humid temps = higher rates of decomposition.

[NB: more carbon being transferred between stores.]

141
Q

Why do we need to monitor changes to both the water and carbon cycles?

A

In order to establish patterns in the past and so you are able to estimate future patterns. We want to monitor these changes to look at the impacts of climate change (short and long term).

142
Q

What changes would scientists look to measure? (4)

A
  1. Global air temperatures.
  2. Sea surface temperatures.
  3. Sea ice thickness.
  4. Rates of deforestation.
143
Q

How do scientists carry out the monitoring of the changes? Why?

A

Remote sensing - the scanning of the earth by satellites or drones to obtain information.

Because - ground-based measurements of environmental change at the global scale are impractical.

144
Q

How is arctic sea ice monitored by remote sensing? (2)

A

Satellite - NASA’s Earth Observing System (EOS) satellites have monitored sea ice growth and retreat since 1978.

Analysis - measures microwave energy radiated from Earth’s surface. Comparison of time series images to show changes.

145
Q

How does the atmosphere link the water and carbon cycles?

A
  1. Atmospheric CO2 has greenhouse effect.
  2. Plants & phytoplankton: extract water from the soil and transpire; photosynthesise; act as carbon store
  3. Water evaporated from oceans to atmosphere.
  4. Carbon dioxide is exchanged between oceans/atmosphere.
146
Q

How do oceans link the water and carbon cycles? (3)

A
  1. Atmospheric CO2 levels influence: sea level; melting of ice sheets and glaciers; sea surface temps (SSTs) & thermal expansion of oceans; air temps.
  2. Ocean acidity increases when exchanges of carbon dioxide aren’t in balance.
  3. Solubility of CO2 increases in the oceans with lower SSTs.
147
Q

How does vegetation and soil link the water and carbon cycles? (3)

A
  1. Temp and rainfall affect decomposition rates & the release of carbon dioxide to the atmosphere.
  2. Water availability influences: inputs of organic litter to the soils; rates of photosynthesis; NPP; transpiration.
  3. Water storage capacity of soils increases with organic content.
148
Q

How does the cryosphere link the water and carbon cycles? (4)

A
  1. CO2 levels in atmosphere determine intensity of greenhouse effect & melting of ice sheets, glaciers, sea ice and permafrost.
  2. Melting exposes land and sea surfaces which absorb more solar radiation and raise temperatures further.
  3. Permafrost melting exposes organic material to oxidation and decomposition which releases CO2 and methane.
  4. Run-off, river flow and evaporation respond to temperature change.
149
Q

What is the AO2 ideas regarding interlinkages between cycles?

A

To what extent is the interdependence a two-way relationship?

Water is more important - if carbon shut down, water could continue to cycle; if water cycle shut down, carbon would not be able to cycle (i.e. carbon cycle processes reliant on presence of water- photosynthesis & decomposition).

In some places, the links are stronger than the others… (Amazon v Tundra - photosynthesis etc)

Atmosphere is really important - key factor in influencing all of the links between the stores

150
Q

What has caused the modification of stores in the water and carbon cycles, and the rate of transfer between the stores? (3)

A
  1. Population & economic growth.
  2. Deforestation.
  3. Urbanisation.
151
Q

Where is the human impact on the water cycle most evident?

A

Rivers and aquifers.

152
Q

How have humans impacted rivers and aquifers? (2)

A
  1. Rising demand for water (irrigation, agriculture, public supply) has created acute shortages.
  2. Quality of fresh water resources have declined.
153
Q

Place specifics of human impacts on rivers and aquifers (2)

A
  1. Colorado Basin (SW USA) - surface supplies diminished as more water abstracted from rivers, and huge amounts are evaporated from reservoirs (Lake Mead & Powell).
  2. Bangladesh - over-pumping of aquifers in coastal regions led to incursions of salt water, often making water unfit for irrigation & drinking.
154
Q

What flows/stores of water cycle does deforestation and urbanisation impact? (4)

A
  1. Reduce evaporation (thus reduce precipitation).
  2. Increase surface run-off.
  3. Decrease through-flow.
  4. Lower water tables.
155
Q

Place specific example of impacts on water cycle flows/stores

A

Amazonia - forest trees key component of water cycle: water to atmosphere by evaporation, returned by precipitation. Deforestation has broken this cycle (climates to dry out).

156
Q

How has human activity impacted flows and stores of carbon? (6)

A
  1. Exploitation of coal, oil and natural gas has removed billions of tonnes of carbon from geological store (e.g. industrialisation of Chinese & Indian economies).
  2. Land use change (deforestation) transfers approximately 1bn tonnes carbon to atmosphere annually (stored as atmospheric CO2).
  3. Deforestation (reduced planet’s forest cover by 50%) = amount stored in biosphere, and fixed by photosynthesis, has decreased.
  4. Phytoplankton (absorb more than 50% CO2 from fossil fuels) threatened by acidification of oceans.
  5. Soil (important store) degraded by erosion caused by deforestation and agricultural mismanagement.
  6. Stores in wetlands (drained for cultivation & urban dev.) have been depleted as they dry out and are oxidised.
157
Q

How has climate change impacted the water cycle? (4)

A
  1. Global warming = + evaporation (amount of water vapour in atmosphere)- more vapour (GHG) = feedback effect (+ global temps, increase evaporation & precipitation).
  2. Increased precipitation = higher run-off & greater risk of floods.
  3. Water vapour = source of energy in atmosphere (releasing latent heat on condensation)- more energy in atmosphere = extreme weather events more frequent (hurricanes, mid-latitude storms).
  4. Global warming = + melting of glaciers, ice sheets (Greenland) & permafrost (Artic tundra) = water storage in cryosphere shrinks (transferred to oceans & atmosphere).
158
Q

How has climate change impacted the carbon cycle? (4)

A
  1. Higher temps = + rate of decomposition & accelerate transfers of carbon from biosphere & soil to atmosphere.
  2. In humid tropics, increase aridity & threaten extent of forests- forests replaced by grasslands = carbon stored in tropical biomass diminish. BUT high latitudes, global warming = boreal forests of Siberia and Canada expand polewards.
  3. Carbon frozen in permafrost of tundra released (temps rise = allow oxidation & decomposition of vast peat stores).
  4. Acidification of oceans (absorption of excess CO2 from atmosphere) reduces photosynthesis by phytoplankton, limiting capacity of oceans to store carbon.
159
Q

AO2 of long-term climate change

A

Movement of carbon into/out of atmosphere will vary regionally, depending on changes in rates of photosynthesis, decomposition and respiration.

160
Q

What % of the Earth’s land surface is occupied by wetlands?

A

6-9%

161
Q

What % of the terrestrial carbon pool do they contain?

A

35%

162
Q

What is the common feature of wetlands?

A

A water table at or near the surface causing the ground to be permanently saturated

163
Q

Problems faced by wetlands (3)

A
  1. Population growth, economic development & urbanisation have placed huge pressure on wetlands​
  2. A significant loss in biodiversity and wildlife habitats
  3. Transfer of huge amount of stored CO2 and CH4 to the atmosphere
163
Q

What do wetlands include? (5)

A
  1. Freshwater marshes​
  2. Salt marshes​
  3. Peatlands​
  4. Flood plains
  5. Mangroves
164
Q

Why are wetlands important? (2)

A
  1. Wetlands can help to slow down climate change by naturally absorbing and storing vast amounts of carbon. ​
  2. Wetlands can also help to prepare for, cope with and bounce back from the impacts of climate change.
165
Q

Place specific examples of wetlands (2)

A
  1. In the lower 48 US states - wetland area reduced by 50% since 1600
  2. Canada’s prairie provinces lost 70% of their wetlands in 20th century
  • Wetland restoration programmes in this area have shown that wetlands can store on average 3.25 tonnes C/ha/year
  • Now 112,000 ha have been targeted for restoration in Canadian prairies - should sequester 364,000 tonnes C/year
  • Slow rate of success but a significant sink is being protected
166
Q

Examples of management strategies (4)

A
  1. International Convention on Wetlands (Ramsar)
  2. European Union Habitats Directive
  3. UK - running a number of small-scale schemes from restoring wetlands from farmlands. Raising the water table through controlled flooding
  • 400 ha of grade 1 farmland in Cambridgeshire is being converted back to wetland
  • Will assist the UK government to meet it’s target to restore 500 ha of wetland
  1. Management and restoration of the Everglades
  • The Comprehensive Everglades Restoration Plan (CERP) is a multibillion dollar project passed by Congress in 2000
  • Used to remove excess phosphorus from water before discharging into the Everglades
167
Q

What does restoration focus on?

A

Restoration focuses on raising local water tables to re-create waterlogged conditions

168
Q

How can coastal areas & wetlands on floodplains be restored?

A

Coastal areas of marshland can be restored by breaching sea defences

Wetlands on floodplains can be reconnected to rivers by the removal of flood embankments & controlled floods

169
Q

What are the environmental benefits of wetlands? (3)

A
  1. Wetlands are the most effective carbon sinks on the planet.​
  2. Peatlands store twice as much carbon as all the world’s forests combined ​
  3. Steart’s salt marshes currently store 10,000 tonnes of carbon every year.
170
Q

Human benefits of wetlands? (4)

A
  1. Wetlands have supported human life for millenia and are essential for human health and prosperity.​
  2. Wetlands provide livelihoods for one billion people.​
  3. 50% of international tourists seek relaxation in wetland areas, supporting millions of jobs.​
  4. More than half the world relies on wetland grown produce such as rice for their staple diet.
171
Q

Why is the impact on the carbon cycle of wetland restoration limited?

A

Only occupy 6-9% of Earth’s surface, so even if wholly restored, impact on carbon cycle will be limited.

172
Q

What are the issues with agricultural practices today? (4)

A
  1. Over-cultivation - cultivation which, given environmental resources, is not sustainable in the long term and is evidenced by declining yields, soil exhaustion and erosion
  2. Overgrazing - excessive grazing of land by livestock which destroys or degrades pasture and is not sustainable
  3. Excessive intensification - intensive livestock = 100 million tonnes/year CH4 into atmosphere
  4. CH4 emissions from flooded (padi) rice fields & from the uncontrollable decomposition of manure
173
Q

Examples of land and crop management (5)

A
  1. Zero tillage:
  • Growing crops without ploughing the soil conserves the soils organic content
  • Reduces oxidation and decreases the risk of erosion by wind and water
  1. Polyculture:
  • Growing crops mixed in with trees - the trees will provide year-round ground cover and protects soils from erosion
  1. Crop residues:
  • Leaving crop residues (stems and leaves) on fields after the harvest, to provide ground cover and protect the soils from erosion and from drying out
  • Protects moisture so enables decomposition
  1. Contour ploughing and terracing:
  • Reduces run-off and erosion
  1. Introducing new strains of rice:
  • Grow in drier conditions and therefore produce less CH4
  • Reduces the need for flooded rice fields which reduces the methane emissions
  • Applying chemicals such as ammonium sulphate which inhibit microbial activities that produce CH4.
174
Q

Examples of livestock and manure management (2)

A
  1. Improving the quality of animal food Reduces enteric fermentation so that less food is converted into CH4.
  2. Controlling the way manure decomposes to reduce CH4 emissions Storing manure in anaerobic containers and capturing CH4 as a source of renewable energy.
175
Q

What is enteric fermentation?

A

Digestive process by which carbohydrates are broken down by microorganisms into simple molecules for absorption into the bloodstream of an animal

176
Q

What is CAP and trade and how does it work? (4)

A
  1. It is a market-based approach designed to limit CO2 emissions by providing economic incentives for reducing the emissions of pollutants
  2. Businesses are allocated an annual quota for their CO2 emissions
  3. If they emit less than their quota:
    - Receive carbon credits
    - Carbon credits are traded on international market
  4. If they exceed their quota:
    - Must purchase more credits or receive a financial penalty
177
Q

What are carbon offsets and how are they used?

A

They are credits that are awarded to countries and companies for schemes that help limit the amount of CO2 in the atmosphere

i.e. afforestation, renewable energy, wetland restoration etc

They can be bought to compensate for excessive emissions elsewhere

178
Q

Advantages of cap and trade (4)

A
  1. The trading process can lead to faster cuts in emissions - “Cap and trade allows the market to find the cheapest method to cut emissions”
  2. They increase government revenue - potentially more money spent on renewable resources
  3. The overall cap is gradually reduced over the years - driving a decrease in the amount of carbon emitted. The US emissions decrease of 15% in 10 years
  4. Can encourage green innovations by entrepreneurs
179
Q

Disadvantages of cap and trade (4)

A
  1. Some companies may not change their habits and are happy to buy carbon credits
  2. The system needs to be rigid for it to work - government must be firm and not allow emission extensions
  3. It can encourage companies to cheat/lie about their amount of emissions
  4. Emission credits are cheaper to buy than spending on more climate friendly resources
180
Q

Conclusion on cap and trade (3)

A
  1. A cap and trade system will be effective if companies are honest and the government is strict
  2. However, if companies do cheat and government are not strict then it will not be effective
  3. Have raised over $504 million in Ontario for school community projects e.g. Schools being more energy efficient
181
Q

What are international agreements and why are they needed? (3)

A
  1. Formal understandings and commitments between two of more countries
  2. For climate change usually agreed at summits
  3. Solving the problem of CO2 emissions requires international co-operation
182
Q

What is the International Energy Agency (IEA) step by step plan? (3)

A
  1. IEA says that no new fossil fuel boilers should be sold from 2025 to be able to achieve net zero emissions by 2050
  2. The next goal would be to phase out petrol and diesel cars by 2035
  3. This is part of a 400 step plan which has been internationally agreed
183
Q

What is the UN Framework Convention on Climate Change (UNFCCC)? (3)

A

Agreed, 1992- is the main international treaty on fighting climate change

Objective is to prevent dangerous man-made interference with the global climate system.

The EU and all its member countries are among the 197 Parties of the Convention.

184
Q

What was the Kyoto Agreement (1997)? (3)

A
  1. Most advanced countries agreed legally binding legislation to reduce CO2 emissions - 1st agreed about emissions ever
  2. China and India (two of the biggest emitters) were exempt, and the US and Australia refused to ratify
  3. Kyoto agreement expired in 2012
185
Q

What was the Paris Agreement (2015)? (4)

A
  1. Aims to reduce global CO2 by 60% by 2050
  2. Keep global warming below 2 degrees Celsius
  3. Advanced countries said they would financially support poorer countries
  4. Trump administration controversy about Paris Agreement - USA pulled out of agreement, followed by China
186
Q

What was the COP26- Glasgow (2022) Agreement? (4)

A
  1. Secure global net zero by mid-century and keep 1.5 C degrees within reach by:
    - accelerating the phase-out of coal
    - curtailing deforestation by 2030
    - speeding up the switch to electric vehicles
    - encouraging investment in renewables.
  2. Adapt to protect communities and natural habitats.
  3. Mobilise at least $100bn in climate finance per year.
  4. Work together to deliver; finalising the Paris Rulebook and accelerate action to tackle the climate crisis through.
187
Q

What does afforestation involve?

A

The planting of trees in deforested areas or in areas that have never been forested

188
Q

Why is planting trees important? (3)

A
  1. Trees are carbon sinks - can help reduce atmospheric CO2 levels in the medium to long-term and combat climate change
  2. Reducing flood risks & soil erosion
  3. Increasing biodiversity
189
Q

What is desertification?

A

The reduction in agricultural capacity due to overexploitation of resources and natural processes such as drought. Only in extreme cases does it result in desert-like conditions.

190
Q

What is land degradation?

A

The deterioration of land suitably for agriculture by soil erosion, desertification and salinisation.

191
Q

What is the UN REDD Scheme?

A

The UN’s Reducing Emissions from Deforestation and Forest Degradation (REDD) scheme incentivises developing countries to conserve their rainforests by placing a monetary value on forest conservation

192
Q

What were UN REDD Scheme’s aims in China? (3)

A
  1. Aims to afforest 400,000km2 (size of Spain) by 2050

NB: 2000-09, 30,000km2 successfully planted

Wider aim - stop desertification; balance CO2 from industrial activity; create usable land in future

193
Q

What went wrong with the scheme in China? (2)

A
  1. Wrong tree species
  2. Too water intensive
194
Q

Positives of UN REDD Scheme in China (6)

A
  1. The new forest can hold between 12 and 30 tones of CO2 per acre
  2. 23% of China is now trees 198 million acres
  3. In 2019 China planted trees on 17 million acres of land which is about the size of Ireland
  4. Mainly on land that became desertified due to intensive agriculture
  5. Plan to plant another 16.6 million acres this year
  6. This accounts for 5% of global tree coverage growth from 2000 to 2007
195
Q

What problem is forestry trying to solve?

A

Deforestation

196
Q

Which agencies recognise the crucial role of forests in the water cycle? (2)

A
  1. United Nations (UN)
  2. World Bank (WB)
197
Q

Examples of UN/WB’s programmes (2)

A
  1. UN’s Reducing Emissions from Deforestation and Forest Degradation (REDD) programme
  2. WB’s Forest Carbon Partnership Facility (FCPF)
198
Q

What do these programmes do?

A

Fund over 50 partner countries in Africa, Asia-Pacific, South America

199
Q

What financial incentives are provided to protect & restore forests?

A
  1. Carbon offsets
  2. Direct funding
200
Q

Who has Brazil received support from to protect its forests? (4)

A
  1. UN
  2. WB
  3. World Wildlife Fund (WWF)
  4. German Development Bank
201
Q

What programme is now taking place in the Amazon basin?

A

The Amazon Regional Protected Areas (ARPA) programme

202
Q

Facts about ARPA (3)

A
  1. Now covers nearly 128m acres of the Amazon basin
  2. Targeted area of 150m acres
  3. Areas included in programme are strictly protected (75% decrease in deforestation rates between 2000 and 2012)
203
Q

What are the benefits of ARPA? (5)

A
  1. Stabilising the regional water cycle
  2. Offsetting 1.4bn tonnes carbon a year
  3. Supporting indigenous forest communities
  4. Promoting ecotourism
  5. Protecting the genetic bank provided by thousands of plant species in the forests
204
Q

What are potential limitations to forestry projects? (2)

A
  1. Hard to incentivise people who rely on income created by deforestation
  2. Hard to ensure the management is being carried out (hard to survey large amounts of forest)
205
Q

What sector is the biggest consumer of water? Figures?

A

Consumer: agriculture

Figures: globally, accounts for 70% of water withdrawals // 90% of consumption

206
Q

How does water wastage occur in agriculture? (2)

A
  1. Evaporation
  2. Seepage through inefficient water management (e.g. over-irrigating crops)
207
Q

Examples of improved management techniques which minimise water losses to evaporation (3)

A
  1. Mulching - layer of material applied to surface of soil = conservation of soil moisture, improving fertility & health, reducing weed growth
  2. Zero soil disturbance - arable land where no tillage is applied between harvesting and sowing (sown directly into soil)
  3. Drip irrigation - tubing with emitters on ground by side of plants: slowly drip water into soil at root zone. As moisture levels maintained at optimum range, plant productivity & quality improve
208
Q

Examples of management techniques to reduce losses to run-off (2)

A
  1. Terracing - an agricultural practice that suggests rearranging farmlands or turning hills into farmlands by constructing specific ridged platforms
  2. Contour ploughing - method of plowing furrows that follow the curves of the land rather than straight up and down slopes: slows the water flow and helps save precious topsoil
209
Q

Why are these agricultural techniques limited spatially?

A

Techniques used little outside the developed world

210
Q

What do domestic and industrial water allocation systems try to do? (4)

A
  1. Equally apportion water resources among users
  2. Protect existing water users from having their supplies diminished by new users
  3. Govern the sharing of limited water during droughts (when supplies inadequate to meet needs)
  4. Facilitate efficient water use
211
Q

What is the Colorado management scheme?

A
  1. Divide up resources between downstream states.
  2. 90% used for irrigation (agriculture).
212
Q

What is a limitation of the Colorado scheme?

A

Less water allocated = less crops produced.

213
Q

In which country is the state government responsible for allocating water?

A

Australia

214
Q

Why are domestic and industrial water allocation systems spatially limited?

A

Not seen in developing world

215
Q

What do specific targets for drainage basin planning include? (3)

A
  1. Run-off
  2. Surface water storage
  3. Groundwater
216
Q

How is rapid run-off controlled? (3)

A
  1. Reforestation programmes in upland catchments
  2. Reducing artificial drainage
  3. Extending permeable surfaces (e.g. gardens, green roofs) in urban areas
217
Q

How is surface water storage improved?

A

Conserving and restoring wetlands (including temporary storage on floodplains)

218
Q

How are groundwater levels maintained? (2)

A
  1. Limiting abstraction (e.g. for public supply, farming and industry)
  2. Artificial recharge (water injected into aquifers through boreholes)
219
Q

What is the EU initiative and facts?

A

EU’s Water Directive Framework

  • 10 river basin districts (England & Wales) have been defined
  • Each district has its own River Basin Management Plan (published by Environ. Agency and DEFRA)

What does it do? Sets targets in relation to, for example, water quality, abstraction rates, groundwater levels, flood control, floodplain dev. & status of habitats and wildlife

220
Q

Limitations of drainage basin planning

A
  1. Costly
  2. Small scale
221
Q

What are the different types of clouds?

A
  1. Cumuliform clouds - air heated locally through contact with Earth’s surface = convection etc.
  2. Stratiform/layer clouds - air masses move horizontally across a cooler surface (often ocean) - known as advection.
  3. Wispy, cirrus clouds - form at high altitudes (ice crystals) - do not produce precipitation = little influence on water cycle.
222
Q

What are the different types of rainfall?

A
  1. Convection
  2. Advection
  3. Orographic uplift
  4. Frontal/mixed air masses
223
Q

What is the environmental lapse rate?

A

Vertical temp profile of lower atmosphere at any given time - temp falls by 6.5*C for every 1km height gained.

224
Q

What is dry adiabatic lapse rate?

A

Rate that a parcel of dry air (less than 100% humidity so condensation not taking place) cools. Temp falls 10*C/km gained.

225
Q

What is saturated adiabatic lapse rate?

A

Rate a saturated parcel of air cools as it rises (one in which condensation is occurring) - temp falls 7*C/km gained.

226
Q

Explain the formation of a cloud (3)

A
  1. Ground heated by sun, warms air in contact with surface to 18C -> air is warmer than surrounding air (13C) and so rises as less dense -> vertical movement of air = convection.
  2. Internal temp reaches dew point (8*C) = condensation, clouds start to form - but air continues to rise as long as internal temp > surrounding temp.
  3. Continues to rise until equilibrium is attained (top of cloud - same temp as surrounding = stable = cannot rise further as heavier than surrounding).
227
Q

What happens to parcel of air as it rises?

A

Pressure decreases = parcel of air expands (adiabatic expansion) = less particle collisions (less energy created) = loses latent heat to surrounding = temp falls.

A Level Geography (OCR) (13 decks)

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