Earths life support systems. Flashcards
1
Q
List some of the importance’s of water
A
- Creates benign thermal conditions
(Ocean slow release of heat, clouds reflecting solar radiation and water vapour absorbing long-wave radiation) - Metabolic medium for photosynthesis, respiration and transpiration streams.
- Economic activity
(Generate electricity, irrigate crops, provide public demand for water and used in industry)
2
Q
List some of the importances of carbon.
A
- Biological significance (carbon is used in the composition of biological molecules such as proteins, carbohydrates and nucleic acids)
- Economic resource (fossil fuels utilised in industry and timber)
- Domestic purpose (heating)
- Insulator
3
Q
What type of systems are the global carbon and water cycle and why?
A
- Closed systems
Driven by the suns energy, only energy crosses the boundary, not material.
4
Q
Can a carbon and water cycle be an open system?
A
YES
In small scale, such as in drainage basins and forest ecosystems material can move across defined boundaries.
5
Q
What % of all water on earth does the ocean comprise?
A
97%
6
Q
What is one of the smallest stores of water and why?
A
- Atmospheric store.
There is a rapid flux of water into and out of the atmosphere (residence time 9 days)
7
Q
List inputs of water into the atmosphere
A
- Evapotranspiration
- Ablation (melting and sublimation)
8
Q
List outputs of water from the atmosphere
A
- Precipitation
- Condensation
9
Q
Name flows in the water cycle
A
- Precipitation
- Evaporation
- Runoff
- Groundwater flow
10
Q
What is the difference between groundwater flow and runoff?
A
- Groundwater flow is the HORIZONTAL movement of water within aquifers
- Runoff is the movement of water across land surface.
11
Q
Define infiltration
A
The vertical movement of rainwater through the soil
12
Q
Define ‘system’
A
A system is a set of interrelated objects comprising components and processes that are linked to create a dynamic whole.
13
Q
What does the global carbon cycle consist of?
A
- Stores
- Sinks
- Flows (connects)
14
Q
Name the principal stores in the carbon cycle
A
- Atmosphere
- Oceans
- Carbonate rocks
- Fossil fuels
- Plants
- Soils
15
Q
What is the biggest carbon store?
A
Carbonate rocks (such as limestone and chalk alongside deep ocean sediments)
16
Q
What are the two categories of carbon cycle?
A
- Slow carbon cycle
- Fast carbon cycle
17
Q
What is the slow carbon cycle
A
The circulation of carbon that has been stored in rocks, sea floor sediments and fossil fuels.
These are characterised by long residence times (150M years)
18
Q
What is the fast carbon cycle?
A
The rapid circulation of carbon between atmosphere, oceans and biosphere.
These transfers are between 10-1000x faster than the slow carbon cycle transfer.
19
Q
What are the key components of the fast carbon cycle
A
- Terrestrial plants and phytoplankton (absorb CO2)
- Respiration and decomposition (returns CO2)
- Dissolving in the ocean.
20
Q
What are the main flows involved in the slow carbon cycle?
A
- Accumulation of crustacean remains that have been subjected to pressure, becoming sedimentary rocks. (INPUT)
- Subduction: the sedimentary rock is sub-ducted into the upset mantle and are vented in volcanic eruptions. (OUTPUT)
- Weathering:
If exposed, the rocks are attacked by chemical weathering such as carbonation. Rainwater combines with atmospheric CO2 to form a weak acid which attacks carbonate minerals. OUTPUT
21
Q
State the water balance equation
A
Precipitation (P) = Evapotranspiration (E) + Streamflow (Q) ± Storage
22
Q
What are the 7 principal flows in the water cycle?
A
- Precipitation
- Evaporation
- Transpiration
- Run-off
- Infiltration
- Percolation
- Throughflow
23
Q
How is precipitation formed?
A
- Water vapour in the atmosphere cools to its dew point.
- It condenses into tiny water droplets or ice particles, forming clouds.
- The droplets or ice particles aggregate, reach a critical size and leave as precipitation
24
Q
In what 3 ways can precipitation impact drainage basins?
A
- Form of precipitation
Precipitation can fall as snow in high latitude and mountainous catchments and remain on the ground for months - creates considerable time lag between precipitation and runoff - Intensity of precipitation
The amount falling in a given time, if high it undergoes through-flow, as it is falling at a rate exceeding the infiltration capacity in the soil. - Duration of precipitation
Length that the event lasts - prolonged events cause saturation of the soil which creates overland flow and potential river flooding
25
How is transpiration influenced by temperature and wind speed?
- Deciduous trees shed their leaves in climates with dry or cold seasons to reduce moisture loss.
- In areas with higher wind speed, such as the unsheltered tundra, water potential is effected.
26
What is a feature of cumuliform clouds and how are they formed?
- Flat bases and considerable vertical development
- Occur when air is heated locally through contact with earths surface, causing heat parcels to rise in convection and expand (due to fall in altitude pressure) which then cool.
27
What is a feature of stratiform clouds and how are they formed?
- Layered clouds
- Air moves horizontally across a cooler surface and mixes with turbulence (ADVECTION)
28
What is a feature of cirrus clouds?
- Wispy clouds formed at high altitude.
- DO NOT produce precipitation so have little influence on the water cycle.
29
What are the 4 ways in which clouds are formed?
- **Convection**
Air is warmed by contact with the ground or sea surface and rises. As the air rises and pressure falls it cools by expansion (adiabatic expansion).
- **Advection**
Air masses move horizontally across a relatively cooler surface.
- **Frontal**
A relatively warm air mass mixes with a cooler one.
- **Orthographic uplift**
Air masses are forced upwards as they cross a mountain barrier or turbulence forces ascent.
30
Name the 3 lapse rates.
- Environmental lapse rate (ELR)
- Dry adiabatic lapse rate (DALR)
- Saturated adiabatic lapse rate (SALR)
31
What is a lapse rate referring to?
The vertical distribution of temperature in the lower atmosphere, and the temperature changes that occur within an air parcel as it rises vertically away from the ground.
32
What is the environmental lapse rate (ELR)
- The vertical temperature profile of the lower atmosphere at any given time.
- The temp falls by 6.5°C for every kilometre of height gained.
33
What is the dry adiabatic lapse rate?
The rate at which a parcel of **dry** air (less than 100% humidity so condensation isn’t taking place) cools.
- Cooling is caused by adiabatic expansion at approx. 10°C/km.
34
What is the saturated adiabatic lapse rate?
The rate at which a saturated parcel of air (where condensation IS occurring) cools as it rises through the atmosphere.
- As condensation releases latent heat the SALR is 7°/km, lower than DALR.
35
Describe convection in more detail
- The ground heated by the sun warms the air in contact with the surface to a temperature warmer than it’s surroundings
- As the air is now warmer than it’s surroundings, it is less dense and therefore buoyant.
- This is **atmospheric instability**, creating freely rising air in a convection current.
- When it’s internal temperature reaches dew point (the same temperature externally) condensation occurs and clouds form.
36
What are the types of stores in the water cycle?
- Oceanic (72% of earths surface)
- Cryosphere (icecaps, ice sheets, glaciers and permafrost)
- Terrestrial water (rivers, wetlands and groundwater)
- Atmospheric
- Biosphere
37
What are carbon cycle stores also known as?
Sinks or pools
38
What are the main flows (or fluxes) between carbon stores?
- Photosynthesis
- Respiration
- Combustion
- Decomposition
- Weathering
39
In the water balance equation, what is meant when there is a positive water balance?
When precipitation exceeds evapotranspiration
40
In the water balance equation, what is meant when there is a negative water balance?
When evapotranspiration exceeds precipitation
41
Define run-off
The movement of water across the land surface
42
Define infiltration
The vertical movement of rainwater through the soil
43
Define percolation
The movement of surface and soil water into underlying permeable rock.
44
What factors affect evapotranspiration?
- Temperature
- Wind speed
- Humidity
- Climatic factors (sunshine, soil moisture)
45
What is meant by orographic rainfall?
When air is forced to rise over hills or mountains.
46
What is meant by frontal rainfall?
When air masses of different temperatures and densities meet - the warm air rises over the cool sinking air.
47
What is meant by convectional rainfall?
When warm air rises from hot surfaces, causing rainfall
48
Outline cryospheric processes
- **Input**: *Accumulation*: input into a glacial system from snowfall
- **Output**: *Ablation*: output from glacial system due to sublimation and melting.
(These often occur in cycles of glacial periods and interglacial periods)
49
Define *drainage basin*
An area of land drained by a river and its tributaries
50
What type of system is a drainage basin?
- An open system
- It has inputs and outputs of both matter and energy
51
What are the inputs, outputs and flows found in a drainage basin?
- **Inputs**: precipitation
- **Flows and transfers**: throughfall, stem flow, infiltration, percolation, overland flow and groundwater flow.
- **Outputs**: to sea or atmosphere (evapotranspiration).
52
Define groundwater store
Water stored underground in permeable and porous rock
53
Define channel store
The volume of water in a river channel
54
Define stemflow
Water flows down the stems of plants or trees
55
What is meant by infiltration rate?
The speed at which water soaks into the soil.
56
What 3 flows enter streams and rivers?
- Infiltration followed by throughflow to stream and river channels
- Overland flow across the ground surface
57
Define throughfall
Water moving from vegetation to the ground
58
Define channel flow
The flow of water in rivers
59
Define leakage
Loss from groundwater stores
60
What is meant by saturated overland flow?
The idea that overland flow only occurs when soil becomes oversaturated and the water table rises to the surface
61
Per year on average, what is the flux of carbon from the atmosphere to the biosphere from photosynthesis?
120 gigatonnes (GT)
62
Describe the role of chemical weathering in the carbon cycle
- Most weathering involves rainwater containing dissolved CO2.
- This creates a weak carbonic acid that can slowly dissolve limestone and chalk in *carbonation*.
63
In what 2 ways does the ocean sequester carbon?
- The physical (inorganic) pump
- The biological (organic) pump
64
What is involved with the physical (inorganic) pump of carbon?
- When carbon is distributed vertically by oceanic currents
- At high latitudes cold water sinks and carbon is transferred deep into the ocean
- This downwelling carries dissolved carbon to ocean depths where individual molecules can remain for centuries
- Eventually, deep ocean currents transport carbon to areas of upwelling - the cold, carbon rich water rises to the surface and CO2 diffuses back to the atmosphere.
65
What is involved with the biological (organic) pump of carbon?
- Phytoplankton fixates carbon in photosynthesis, and other marine organisms such as crustaceans use dissolved carbon for shells.
- When organisms die, organic matter sinks into deep water and releases carbon dioxide into the deep water.
- (In addition, some materials form layers of carbon rich sediments which over millions of years turn into sea-floor sediments in the slow carbon cycle).
66
1/2 of carbon fixation from photosynthesis takes place in the oceans, true or false?
True
67
List the water cycle stores in a drainage basin
- Vegetation store (interception store)
- Surface storage
- Soil moisture
- Groundwater store
- Channel store
68
How is dynamic equilibrium achieved in both the water and carbon cycle
Negative feedback loops
69
What is an example of negative feedback in drainage basins (example of water cycle)?
- In a drainage basin with unusually heavy rainfall there will be an increase in the amount stored in aquifers.
- This in turn will raise the water table, increasing flows from springs until the water table reverts to normal levels
70
What is an example of negative feedback in the carbon cycle?
- Burning of fossil fuels increases atmospheric CO2, but at the same time stimulates photosynthesis.
- This negative feedback response should remove excess CO2 from the atmosphere and restore equilibrium
71
How does the land-use change of urbanization impact the water cycle?
- Urbanization introduces artificial surfaces that are largely impermeable, so infiltration is reduced and runoff accelerated.
- Urban areas have drainage systems to remove surface water rapidly, so there is a lack of lag time between precipitation and transfer to rivers - creating floods.
- This, in particular, occurs where urban development is on floodplains - reducing water storage capacity, increasing river flow and flooding
72
How does the land-use change of urbanization impact the carbon cycle?
- Urban growth removes vegetation and replaces it with urban surface
- This dramatically reduces the biosphere store of organic carbon
- In addition, there is a higher rate of CO2 emission due to urban activity such as vehicle usage and industry.
73
How does the land-use change of farming impact the water cycle?
- Irrigation diverts water from rivers and groundwater supplies to cultivated land, and some of this water is used by plants from soil storage and released by transpiration.
- Agroecosystems (farmland) has lower interception, evaporation and transpiration compared to forest ecosystems, commonly cleared for this.
- The activity of ploughing increases evaporation and soil moisture loss
- Ploughing creates furrows when downslope - these act as drainage channels which accelerates run-off and soil erosion.
- Heavy machinery compacts soils.
74
How does the land-use change of farming impact the carbon cycle?
- Clearance for farming reduces storage in both above and below ground biomass.
- The soil carbon store is depleted by ploughing due to exposing exposing organic soil matter to oxidation.
- There is a further depletion of the soil carbon store when plants are harvested and only small amounts of organic matter are returned to the soil - allowing soil erosion.
- Livestock release methane
- Tractors emit CO2
75
How does the land-use change of forestry impact the water cycle?
- Plantations of natural forests increase interception of rainfall, for example *conifers* which are evergreen and planted at high density.
- Forestry is inputting a higher biosphere store
- Evaporation increases as leaf store water evaporates directly back to the atmosphere.
- Run-off and stream discharge is reduced due to interception
- As a result, lag times and lengthened, peak flow is low and total discharge is low in plantation areas.
- Transpiration is facilitated, being higher than farm or moorland areas.
- Clear felling DOES create sudden, but temporary changes to the local water cycle which has the opposite effect of above.
76
Out of urbanization, agriculture and forestry, which land-use change can promote water and carbon cycles?
Forestry
77
How does the land-use change of forestry impact the carbon cycle?
- Converting land to planted forest increases carbon stores.
- Through photosynthesis, forest trees extract CO2 from the atmosphere and sequester it (most carbon is stored in wood).
- The soil store is enhanced
- However, trees are only active carbon sinks for the first 100 years following planting, as after it is balanced by inputs of litter to the soil and respiration and activities of soil decomposers. SO, plantations have a rotation of felling and replanting.
78
What case do we need to remember for water extraction?
The River Kennet (Southern England)
79
What is water extraction?
The process of taking water from a surface or ground source either temporarily or permanently.
- It is usually motivated by public, agricultural or industrial demand.
80
Contextualize the River Kennet water extraction case study
- The River Kennet is in Southern England, draining **1200km²** in Wiltshire and Berkshire.
- The upper catchment area comprises of chalk which is highly permeable, so *groundwater* contributes most of the Kennet's flow.
- Several urban areas rely on water from the Kennet Basin to meet public supply, such as Swindon.
81
What are the impacts of water extraction from the River Kennet?
- Rates of extraction have *exceeded* rates of recharge, so the falling water table has reduced flows in the Kennet by 10-14%.
- Lower flows have reduced flooding and temporary areas of standing water and wetlands around Marlborough and Hungerford.
- A significant event was the 2003 drought, where flows fell by 20% and up to 40% during the 1990s.
- Lower groundwater has caused springs and seepages to dry up, reducing the incidence of saturated overland flow in the Marlborough Downs.
82
Define 'aquifer'
- An aquifer is a permeable or porous band of water-bearing rock, such as chalk.
- Groundwater is extracted from aquifers.
83
What is an 'artesian aquifer'
- An artesian aquifer / basin is where sedimentary rocks form a basin shape or *'syncline'*.
- There is an aquifer trapped between two impermeable rock layers, potentially containing groundwater that is under *artesian pressure*.
- A well could allow the water to flow to the surface under its own hydrostatic pressure - an artesian aquifer.
84
What is an example of an artesian basin?
London!
85
How do fossil fuels impact the carbon cycle?
- Approximately 10 billion tonnes of CO2 are released into the atmosphere annually, as fossil fuels accounted for 85% of emissions in 2019.
- Anthropogenic carbon emissions comprise less than 10% of the natural influx from the biosphere and oceans to the atmosphere, they impact significantly on the size of the atmosphere, ocean and biosphere carbon stores.
- Combustion of fossil fuels and the resulting transfer of carbon from geological stores to the atmosphere, being the main cause of global warming.
86
How does sequestration of waste carbon (human activity) impact the carbon cycle?
- Sequestration of waste carbon, such as carbon-capture-and-storage acts as a solution to the problem of global warming from carbon emissions.
- This is limited, however, as it involves big capital costs of at least 1 billion, it uses large amounts of energy and requires highly specific storage reservoirs such as porous rocks overlain by impermeable strata
87
Discuss positive feedback in the global water cycle caused by global warming
- Rising temperatures increases evaporation and the atmosphere holds more vapor
- From the atmosphere holding more vapor, there is greater cloud cover and more precipitation.
- These changes create a *positive feedback effect*, this is because water vapor is a greenhouse gas and increases absorption of long-wave radiation from the earth, causing further rise in temperature.
88
Discuss negative feedback in the global water cycle in response to global warming
- Atmospheric water vapor can induce negative feedback
- More water vapor creates greater cloud cover which reflects more solar radiation back into space, so smaller amounts of solar radiation are absorbed by the atmosphere, oceans and land -----> average global temperatures fall.
89
What is an example of small-scale negative feedback in the water cycle?
- In individual trees
- In most years, precipitation is sufficient to satisfy an individual tree's demand for water.
- However, in drought years that bring about disequilibrium, shallow-rooted trees such as birch become stressed: water lost in transpiration is not replaced by similar uptake of water from the soil
- The tree responds by reducing transpiration losses by shedding some or all of its leaves, restoring water balance.
90
Discuss negative feedback in the carbon cycle in response to global warming
- Negative feedback can neutralize rising levels of atmospheric CO2 by stimulating photosynthesis, in a process called *carbon fertilization*.
- Excess CO2 is extracted from the atmosphere and stored in the biosphere.
- Over a long time, some of this carbon would be stored long-term in soils or oceans, allowing the system to return to a steady state.
91
Discuss positive feedback in the carbon cycle as a result of global warming
- Global warming will intensify the carbon cycle, speed up decomposition and release more CO2 to the atmosphere, amplifying the greenhouse effect.
- Another example is the tundra experiencing Arctic sea ice and snow cover shrinkage. Large expanses of sea and land are now exposed. More sunlight is absorbed, warming the tundra and melting the permafrost, a major store.
92
What are two short term changes to carbon and water cycles?
- Diurnal changes
- Seasonal changes
93
How do short term diurnal changes interact with the water cycle?
- At night time, there are lower temperatures which reduce evapotranspiration.
- Precipitation, by convection, is a daytime phenomenon as it is dependent on direct heating of the ground surface by the sun.
- Convectional rainfall is usually in the afternoon
94
How do short term diurnal changes interact with the carbon cycle?
- During the daytime, photosynthesis flows occur which transfers CO2 from atmospheric stores to the biosphere.
- At night-time, due to lack of sunlight presence, respiration exceeds intake of CO2, and CO2 is released back into the atmosphere.
95
How are seasonal changes significant in the water cycle?
- Evapotranspiration is at it's highest rate in the summer as solar radiation peaks, and at its lowest in winter.
96
How are seasonal changes significant in the carbon cycle?
- Seasonal variations are shown by month-to-month changes in the *net primary productivity* of vegetation (NPP).
- In middle and high latitudes, day length or *photoperiod*, and temperature drive seasonal changes in NPP.
- During the summer months, in the Northern Hemisphere, there is a net flow of CO2 from the atmosphere to the biosphere as vegetation is in full foliage, so photosynthesis is rapid.
- When summer ends the flow is reversed and natural decomposition releases CO2 back to the atmosphere.
- In response to warm temperatures, ecosystems extract huge amounts from the atmosphere. In addition, this occurs with algal blooms where there is an explosion of algae colonies in oceans stimulated by rising water temperatures, sunlight and lengthened photoperiod.
97
What has the long term impact of glacial periods had on the water cycle?
- A long term change has been from glacial periods
- During glacial periods, the water cycle underwent a number of changes.
- There was a net transfer from oceanic stores to storage in the cryosphere. As a result, the sea level worldwide fell by 100-130m
- As the glacial period advanced, the cryosphere destroyed extensive tracts of forest and grassland, so the area covered by vegetation and water stored in the biosphere shrunk.
- Glacial-period tropical climates became drier, so deserts and grassland displaced large areas of rainforest.
- Lower rates of evapotranspiration from destruction from the biosphere reduced exchanges of water between the atmosphere and biosphere, oceans and soils.
98
What has the long term impact of glacial periods had on the carbon cycle?
- Glacial periods are characterized by a dramatic reduction of CO2 in the atmosphere.
- It is possible that this is due to changes in ocean circulation during glacial periods that bring nutrients to the surface and stimulate phytoplankton growth.
- The phytoplankton may fix large amounts of CO2 in photosynthesis before dying and contributing to the organic (biological) pump.
- Lower ocean temperatures also make CO2 more soluble.
- In addition, the terrestrial biosphere store shrinks during glacial periods due to the destruction from ice sheets. Also, the tropics become grassland and deserts.
- With the land surface buried by ice, carbon stored in the soils will no longer be exchanged with the atmosphere.
- With less vegetation cover, fewer forests, lower temperatures and lower precipitation, NPP and the total volume of carbon fixed in photosynthesis will decline. The implications of this are an overall slowing of the carbon flux and smaller amounts of CO2 returned to the atmosphere in decomposition.
99
What is the importance of research and monitoring techniques to identify and record changes to the global cycles?
- Cycles are central to supporting life on earth, so understanding these and how they are changing is imperative to managing global challenges such as the impacts of climate change (in terms of consequences on future water, food and energy supply).
- Changes to the water and carbon cycle are important to the analysis of environmental change and the global challenges presented
- Understanding regional variations in sources and sinks of CO2 helps to identify sequestration and emission management options.
100
What are examples of monitoring of the carbon and water cycles?
- NASA's Earth Observing System (EOS) satellites monitoring sea ice growth and retreat.
- ESA albedo (reflectivity) images from various satellites to measure deforestation and land use changes.
101
What stores do you consider when discussing how the carbon and water cycles are interlinked?
- Atmosphere
- Oceans
- Biosphere (vegetation and soil)
- Cryosphere
102
How are the carbon and water cycles interlinked and interdependent related to the atmosphere?
- Atmospheric CO2 has a greenhouse effect
- CO2 plays an important role in photosynthesis by terrestrial plants and phytoplankton. Plants, which are carbon stores, extract water from the soil and transpire it as part of the water cycle.
- CO2 is exchanged between the two stores as plants are able to photosynthesize and respire.
103
How are the carbon and water cycles interlinked and interdependent in relation to oceans?
- Ocean acidity increases when exchanges of CO2 are not in balance (inputs exceeding outputs).
- The solubility of CO2 in the oceans increases with lower sea surface temperatures.
- Reciprocally, CO2 levels influence sea surface temperatures via the greenhouse effect.
- CO2 levels also influence the thermal expansion of oceans, air temperatures, the melting of ice sheets and sea level.
104
How are the carbon and water cycles interlinked and interdependent related to vegetation and soil?
- Water availability affects rates of photosynthesis, NPP, inputs of organic litter to soils and transpiration (ultimately facilitates or inhibits carbon flows).
- The water-storage capacity of soils increases with organic content.
- Temperatures and rainfall affect decomposition rates and the release of CO2 to the atmosphere - mediated by the atmospheric store of water, and the GHE from water vapor and carbon.
105
How are the carbon and water cycles interlinked and interdependent related to the cryosphere?
- CO2 levels in the atmosphere determine the intensity of the greenhouse effect and melting of ice sheets, glaciers, sea ice and permafrost.
- Melting exposes land and sea surfaces which absorb more solar radiation, raising surface temperatures further.
- Permafrost melting exposes organic material to oxidation and decomposition, which releases CO2 and CH4.
- This alters a significant store of water: the cryosphere.
- Run-off, river flow and evaporation respond to temperature change induced by atmospheric CO2.
106
List which ways humans are causing changes in availability of water in the water cycle
- Urbanization
- Rising demand for water
- Deforestation
107
In what way does human activity alter availability of water in aquifers?
- Rising demand for water for irrigation, agriculture and public supply (especially in arid, or semi-arid environments) has created acute shortages.
- For example, the Colorado Basin in SW USA has seen surface supplies diminished as more water is abstracted from rivers, and huge amounts are evaporated from reservoirs.
- Elsewhere, quality of fresh-water is declining due to over-pumping of aquifers in coastal regions of Bangladesh. Incursions of saltwater often make water unfit for irrigation and drinking.
108
In what ways do the human activities of deforestation and urbanization alter *availability* of water?
- Deforestation and urbanization reduces evapotranspiration, and therefore precipitation.
- For example, in Amazonia, forest trees are a key component of the water cycle, transferring water to the atmosphere by evapotranspiration -- which is then returned by precipitation.
- In places with extensive deforestation, often for urbanization, this cycle is broken which causes climates to dry out, affecting availability of water.
- Urbanization also increases run-off from reducing infiltration which can lower water tables.
109
How does human activity of fossil fuel usage affect the availability of carbon?
- Gas and oil industries exploit fossil fuels for industrial and domestic use, this has removed billions of tonnes of carbon from geological stores.
- Fossil fuels accounts for 84% of primary energy consumption, and around 8 billion tonnes are emitted per year to the atmosphere from combustion.
- In addition, acidification of oceans caused by high atmospheric CO2 threatens the biological carbon store of oceans, and the carbon fixed in the process of photosynthesis in phytoplankton
110
How do human activities of deforestation affect the availability of carbon?
- Deforestation reduces the carbon store in the biosphere and the carbon fixed by photosynthesis
- Massive deforestation has reduces the planets forest cover in historic times by nearly 50%, so the amount stored in the biosphere, and fixed by photosynthesis has declined steeply.
- Increased soil erosion as a consequence of deforestation (and poor agricultural practice) is leading to a decline in the carbon store in soil, not helped as trees cannot input organic litter anymore.
111
What can be the impact of long-term climate change on the water cycle?
- Global warming has increased the amount of evaporation, and subsequently the amount of water vapor in the atmosphere. The positive feedback of water vapor in the atmosphere further increases global temperatures, and the patterns of evaporation + precipitation.
- Increased precipitation from global warming in areas where there is urbanization, building on floodplains and deforestation will increase flood events and risks.
- Water vapor acts as a source of energy in the atmosphere, releasing latent heat on condensation. With higher energy in the atmosphere, extreme weather events such as storms and hurricanes will become more powerful and frequent.
- Global warming accelerates the melting of the cryosphere, thus water storage in this store sinks and is transferred to the oceans and atmosphere.
112
What can be the impact of long-term climate change on the carbon cycle?
- The impacts of climate change on the carbon cycle are much more complex - however, the long term impact of climate change will probably be an increase in carbon stored in the atmosphere, and a decrease of carbon stored in the oceans and biosphere.
- Higher temperatures increase rates of decomposition, and the rate of carbon transfer from the biosphere and soil to the atmosphere will increase
- Where temperatures rise so high that aridity increases, forests will be replaced by grasslands which reduces the carbon store in woody vegetation.
- In contrast, in high latitudes, global warming may enable boreal forests (such as those in Siberia and Canada) to expand polewards.
- In permafrost areas carbon is being released from the frozen ground as temperatures rises.
- Acidification of oceans can limit the capacity of the oceans to store carbon from reducing photosynthesis from phytoplankton.
113
List the types of management strategies used to protect the global carbon cycle
- Wetland restoration
- Afforestation
- Improving agricultural practices
- International agreements to reduce emissions
- Cap and trade
114
How is wetland destruction harmful to the global carbon cycle?
- Wetlands contain 35% of the terrestrial carbon pool, so managing this is crucial to maintain these important carbon sinks
- In mainland USA states wetland has halved since 1600 due to destruction from human pressures
- Destruction of wetlands transfers huge amounts of stored CO2 and CH4 to the atmosphere.
115
How is wetland restoration as a management strategy used to protect the global carbon cycle?
- Restoration programs, such as in Canadian prairies, have shown that wetlands can store on average 3.25 tonnes C/ha/year. Now 112000 ha have been targeted here which should sequester 364,000 tonnes C/year.
- New initiatives such as the **International Convention on Wetlands** and the **European Union Habitats Directive** have been formed to implement this elsewhere.
- The UK government met its target of restoring 500 ha of wetland in 2020.
- At a local level, restoration involves raising water tables to create waterlogged conditions. This is achieved by removal of flood embankments and breaching sea defenses.
116
How is afforestation (as a management strategy) used to protect the global carbon cycle?
- Afforestation can help to reduce atmospheric CO2 levels in the medium to long term and combat climate change (as trees are carbon sinks)
- It can reduce flood risks and soil erosion
- Protecting tropical rainforests from loggers, farmers and miners is an inexpensive way of curbing emissions.
- The **REDD scheme** (**UN's Reducing Emissions from Deforestation and Forest Degradation**) incentivizes developing countries to conserve rainforests through placing a monetary value on conservation. Projects like these are operating in Amazonia and Lower Mississipi.
- China are an example of having a massive government-sponsored afforestation project. By 2050, it aims to afforest an area approximately the size of Spain. The purpose of this was to combat desertification and land degradation in the semi-arid expanses of Northern China.
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How has agricultural techniques damaged the carbon cycle?
- Unsustainable practices such as overcultivation, overgrazing and excessive intensification results in soil erosion and release of CO2.
- Livestock farming produces 100 million tonnes/year of CH4
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Discuss improved agricultural techniques as a way of protecting the global carbon cycle
- *Zero tillage*: growing crops without ploughing to conserve organic content, reducing oxidation and risk of erosion
- *Polyculture*: growing annual crops interspersed with trees, providing all year round cover to prevent soil erosion
- *Mulching*: leaving crop residues on fields following harvest to provide ground cover and input of organic matter
- Avoiding use of heavy machinery that compacts soil
- *Contour ploughing and terracing* on slopes to reduce run-off and erosion
- *Rotational grazing* to prevent over grazing.
- *Manure management*: controlling the way manure decomposes to reduce CH4 emissions via using anaerobic containers and capturing it as a source of energy.
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What are examples of international agreements to reduce carbon emissions?
- **The Kyoto Protocol 1997**
- Most rich countries agreed to legally binding restrictions in emissions.
- This was relatively unsuccessful as EDCs, and the biggest polluters, China and India were exempt -- and countries such as the USA and Australia failed to ratify the treaty.
- **The Paris Climate Convention**
- This was created after the *Kyoto Protocol* expired in 2012.
- The international agreement at the *Paris Climate Convention* came in 2015, with implementation from 2020.
- The **Paris Agreement's** aims are to reduce global CO2 emissions below 60% of 2010 by 2050, and keep global warming below 2°.
- It involves rich countries transferring funds and technologies to poorer countries to achieve their targets.
- This is limited by countries setting their own voluntary targets, the agreement not being legally binding and the timetable being disorganized.
- A controversy is China and India arguing global reductions of CO2 are AC's responsibility as industry is essential to raising living standards and historically, Europe and NA are to blame for contemporary global warming and climate change.
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How is cap and trade (as a management strategy) used to protect the global carbon cycle?
- Cap and trade offers an alternative, international *market-based approach* to limit CO2 emissions.
- All businesses are allocated a quota for CO2 emissions, and if they emit less than their quota they receive *carbon credits* which can be traded on international markets.
- Businesses that exceed quotas must purchase additional credits or incur financial penalties
- *Carbon offsets* are credits awarded to countries and companies for schemes such as afforestation, renewable energy and wetland restoration. These can be bought to compensate for excessive emissions elsewhere.
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List the types of management strategies used to protect the global water cycle
- Forestry
- Water allocations and improved management techniques
- Drainage basin planning
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How does forestry (as a strategy) protect the global water cycle?
- Multilateral agencies such as the UN and World Bank, alongside other organizations and governments fund programs to protect tropical rainforests.
- The UNs REDD scheme and the World Banks **Forest Carbon Partnership Facility** (FCFP) fund over 50 partner countries in Africa, Asia-Pacific and South America
- Financial incentives to protect and restore rainforests are a combination of carbon offsets and direct funding.
- Brazil has received support from the UN, World Bank, WWF and the German Development Bank to protect its forests.
- *Amazon Regional Protected Areas* (**ARPA**) program now covers 128 million acres of the Amazon Basin with plans to extend this to 150 million acres.
- Areas in the ARPA program are strictly protected, with a 75% decrease in deforestation between 2000-2012.
- The benefits in *protecting the global water cycle* is stabilizing the regional water cycle, offsetting 1.4 billion tonnes of carbon/year, supporting indigenous forest communities, promoting ecotourism and protecting the genetic bank of rainforest species.
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How does water allocation and improved management techniques (as a strategy) protect the global water cycle?
- Water allocation concerns the governments decisions on the provision of water resources, influenced by factors such as water scarcity.
- Agriculture is the biggest consumer, globally accounting for 70% of water withdrawals and 90% of consumption.
- Wastage of water occurs from evaporation and seepage through inefficient management (such as overirrigating crops).
- Improves management techniques can be used such as drip irrigation and terracing to prevent runoff and loss.
- Water allocation can be improved with better water harvesting, with storage in ponds and reservoirs - providing farmers with extra water resources
- Recovery and recycling of waste water from agriculture, industry and urban population is feasible, yet unapplied outside ACs.
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What is an example of water allocation as a management technique for the global water cycle?
- The Lower Indus Valley in Pakistan and the US Colorado Basin.
- In the US Colorado Basin, water agreements divide up resources between downstream states. This water is allocated to California, Arizona, Nevada, Utah and New Mexico.
- In Pakistan, the Punjab and Sindh receive 92% of the Indus's flow
- In both regions, the vast bulk of water is used for irrigation
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How does drainage basin planning (as a strategy) protect the global water cycle?
- Drainage basin planning manages water resources at a regional scale.
- Drainage basin management is feasible in adopting an integrated or holistic management approach to accommodate conflicting demands.
- Specific targets for drainage basin planning include: *runoff, surface water storage and ground water*
- Rapid *runoff* is controlled in planning by reforestation in upland catchment areas, reducing artificial damage and extending permeable surfaces in urban areas.
- *Surface water storage* is improved by conserving and restoring wetlands, including temporary storage on floodplains.
- *Groundwater levels* are maintained by limiting abstraction and by artificial recharge - where water is injected into aquifers through boreholes.
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What are examples of drainage basin planning in the UK?
- Projects operating under the **EU's Water Directive Framework**
- 10 river basin districts have been defined, comprising major catchments such as the Severn, Thames and Humber.
- Each district has its own **River Basin Management Plan** published jointly by the Environmental agency and Defra.
- The River Basin Management Plans sets targets in relation to: water quality, abstraction rates, groundwater levels, flood control, floodplain development and status of habitats.
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What is meant by abstraction?
The extraction of water from rivers and boreholes for public demand
