1.4 The carbon cycle and energy security Flashcards
(139 cards)
1
Q
What is the natural carbon cycle?
A
the movement and storage of carbon between the land, ocean and the atmosphere.
2
Q
Where is inorganic carbon found?
A
Found in rocks as bicarbonates and carbonates
3
Q
Where is organic carbon found?
A
Found in plant material and living organisms
4
Q
Types of carbon stores (3)
A
- terrestrial
- oceanic
- atmospheric
5
Q
Define flux
A
the movement/transfer of carbon between stores.
6
Q
What is a carbon sink?
A
any store which takes in more carbon than it emits, so an intact tropical rainforest is an example
7
Q
What is a carbon source?
A
any store that emits more carbon than it stores so a damaged tropical rainforest is an example.
8
Q
Examples of where carbon is present in stores (4)
A
▪ The atmosphere as CO2 and methane
▪ The hydrosphere as dissolved CO2
▪ The lithosphere as carbonates in limestone and fossil fuels like coal, gas and oil
▪ The biosphere in living and dead organism
9
Q
Describe carbon sequestration
A
- the transfer of carbon from the atmosphere to other stores
- can be both natural and artificial.
- For example. a plant sequesters carbon when it photosynthesises and stores the carbon in its mass.
10
Q
What are the main carbon stores? (6)
A
- Marine Sediments and Sedimentary Rocks
- Oceans
- Fossil fuel deposits
- soil organic matter
- atmosphere
- terrestrial plants
11
Q
Describe the global distribution of carbon stores in the lithosphere and biosphere
A
- The lithosphere is the main store of carbon , with global stores unevenly distributed.
- For example, the oceans are larger in the southern hemisphere
- storage in the biosphere mostly occurs on land.
- Terrestrial plant storage is focussed in the tropics and the northern hemisphere.
12
Q
Describe transfers in the carbon cycle
A
- The transfers in the carbon cycle act to drive and cause changes in the carbon cycle over time.
- They all have impacts of varying magnitude over different lengths of time .
- Biological and chemical processes determine how much carbon is stored and released.
- The role of living organisms is very important in maintaining the system running efficiently.
13
Q
Describe the process of photosynthesis
A
- Living organisms convert Carbon Dioxide from the atmosphere and Water from the soil, into Oxygen and Glucose using Light Energy.
- By removing CO ₂ from the atmosphere, plants are sequestering carbon and reducing the potential impacts of climate change.
- Photosynthesis helps to maintain the balance between oxygen and CO ₂ in the atmosphere.
14
Q
Describe the process of respiration
A
- Respiration occurs when plants and animals convert oxygen and glucose into energy which then produces the waste products of water and CO ₂.
- It is therefore chemically the opposite of photosynthesis
15
Q
Describe the balance between plant photosynthesis and respiration
A
- During the day, plants photosynthesise, absorbing significantly more CO ₂ than they emit from respiration.
- During the night they do not photosynthesise but they do respire, releasing more CO ₂ than they absorb.
- Overall, plants absorb more CO₂ than they emit, so are net carbon dioxide absorbers (from the atmosphere) and net oxygen producers (to the atmosphere).
16
Q
Describe the process of combustion
A
- When fossil fuels and organic matter such as trees are burnt, they emit CO ₂ into the atmosphere , that was previously locked inside of them.
- This may occur when fossil fuels are burnt to produce energy, or if wildfires occur.
17
Q
Describe the process of decomposition
A
- When living organisms die, they are broken down by decomposers (such as bacteria and detritivores ) which respire, returning CO₂ into the atmosphere.
- Some organic matter is also returned to the soil where it is stored adding carbon matter to the soil.
18
Q
How does ocean diffusion affect ocean acidity?
A
- The oceans can absorb CO ₂ from the atmosphere, which has increased ocean acidity by 30% since pre-industrial times
- The ocean is the biggest carbon store, but with carbon levels increasing seawater becomes more acidic which is harming aquatic life by causing coral bleaching.
- Many of the world’s coral reefs now under threat.
19
Q
Describe the process of sedimentation
A
- This can happen on land or in the sea.
- For example, when shelled marine organisms die, their shell fragments fall to the ocean floor and become compacted over time to form limestone.
- Organic matter from vegetation and decaying marine organisms is compacted over time, whether on land or in the sea, to form fossil fuel deposits.
20
Q
Describe the processes of carbonation weathering and erosion
A
- Inorganic carbon is released slowly through weathering: rocks are eroded on land or broken down by carbonation weathering.
- Carbonation weathering occurs when CO ₂ in the air mixes with rainwater to create carbonic acid which aids erosion of rocks such as limestone .
- The carbon is moved through the water cycle and enters the oceans.
- Marine organisms use the carbon in the water to build their shells .
- Increasing carbon dioxide levels in the atmosphere, may increase weathering and erosion as a result, potentially affecting other parts of the carbon cycle.
21
Q
Describe the process of rock metamorphosis
A
Extreme heat and pressure forms metamorphic rock, during which some carbon is released and some becomes trapped.
22
Q
Describe volcanic outgassing
A
- There are pockets of CO2 found in the Earth’s crust.
- During a volcanic eruption or from a fissure in the Earth’s crust, this CO2 can be released.
23
Q
Describe short-term variations in carbon fluxes
A
- The quickest cycle is completed in seconds as plants absorb carbon for photosynthesis and then they release carbon when they respire.
- This cycle can slow down when levels of
light or CO2 drop.
24
Q
Describe longer-term variations in carbon fluxes in soil
A
- Dead organic material in soil may hold carbon for hundreds of years.
- Some organic materials may become buried so deeply that they don’t decay, or are buried in conditions unfavourable to decayers (potent low-lying gas, too much water).
- This material will become sedimentary rocks or hydrocarbons by geological processes.
25
Describe differences in carbon storage in different layers of the ocean
- The majority of the processes which take the CO2 out of the atmosphere and into the ocean occur in the top surface layer which makes up only a small proportion of the water in the world’s ocean.
- The carbon rich water in the surface layer is then transferred down into the lower layers of the ocean and transported around the world due to thermohaline circulation.
- It is this circulation which allows such large amounts of carbon to be stored in the sea
26
Describe the role of phytoplankton in ocean sequestation
- Phytoplankton are microscopic organisms that, like plants, photosynthesise.
- They take in carbon and turn it into organic matter.
- As they are the base of the marine food web, when they get eaten, carbon is passed through the food chain.
- CO2 is also released back into the water as these organisms respire.
27
Describe the role of shell-making organisms in ocean sequestation
- Some organisms like Plankton sequester CO2, turning the carbon into their hard outer shells and inner skeletons.
- When these organisms die, some of their shells dissolve into the ocean water meaning the carbon becomes part of deep ocean currents.
- Any dead organisms which sink to the seafloor become buried and compressed, eventually forming limestone sediments (sedimentation)
- Over a long time period these can turn into fossil fuels.
28
describe how CO2 is dissolved into oceans
- some CO2 from the atmosphere will naturally by dissolving into the water.
- This process occurs on the surface of the oceans where CO2 reacts with water to form carbonic acid.
- As the concentrations of CO2 in the atmosphere increase, oceans absorb more CO2, causing them to become more acidic.
- This acidification of the oceans could have long lasting negative effects.
- This movement of CO2 isn’t one way, some will go from the water back into the atmosphere.
- There would come a point where the surface layer of the ocean would become so saturated with carbon that this process would slow down or stop occurring.
29
Why is the concentration of CO2 in oceans different around the world?
- the colder the water, the more CO2 is absorbed
- CO2 concentration is 10% higher in the deep ocean compared to the surface of the ocean.
- Polar regions hold more carbon than tropical regions.
- Warm tropical waters release CO2 to the atmosphere but cold high latitude oceans absorb in CO2 from the atmosphere.
30
Describe thermohaline circulation
- Thermohaline circulation is an ocean current that produces both vertical and horizontal circulation of cold and warm water around the world’s oceans.
- The atmospheric circulation creates large currents in the oceans which transfers water from the warmer tropical areas of the world to the colder polar regions.
- Rate of circulation is slow
- Warm surface waters are depleted of CO2 and nutrients therefore the foundation of the planet’s food chain depends on cool and nutrient rich water which support algae to grow.
31
How do ocean temperatures affect CO2 absorption?
- The rate of absorption of CO2 into the ocean depends on ocean temperatures.
- The colder the water, the more CO2 is absorbed.
- Therefore, as ocean temperatures increase, the
oceans will absorb less CO2 (possibly even emitting some of its stored CO2).
- This would accelerate Climate Change and lead to further ocean warming (positive feedback mechanism)
32
Describe the carbon transfers in the food chain (3)
▪ Primary producers (plants) take carbon from the atmosphere to photosynthesise and release carbon when they respire.
▪ Vegetation growth depends on water, nutrients and sunlight.
▪ When consumers eat plants, carbon from the plants is converted into fats and proteins
33
Describe the carbon transfers in decomposition (3)
▪ Micro-organisms feed on waste material from animals and plants.
▪ Animal and plant remains are easier to decompose compared to wood. Decomposition is faster in tropical climates with high rainfall, temperatures and oxygen levels.
▪ 95% of a tree’s biomass consists of CO2 which is sequestered and converted to cellulose. The amount of carbon stored in trees depends on the balance of respiration and photosynthesis.
34
Variations in carbon fluxes due to terrestrial organisms (2)
● Diurnally – during the day, fluxes are positive from the atmosphere to the ecosystem whereas in the night, fluxes are negative from the atmosphere to the ecosystem.
● Seasonally – In the northern hemisphere during winter, plants die and decay leading to high atmospheric CO2 concentrations but during spring when plants begin to grow, CO2 levels in the atmosphere begin to drop.
35
How much of the world's carbon do soils store?
20-30%
36
Why are arid and semi-arid soils the most important store?
- Any loss by a plant to the ground means that some carbon will transfer to the soil.
- Soil microbes break down plants release carbon to the atmosphere.
- After organisms die, thousands of compounds in soil are decomposed.
37
Factors affecting soil capacity to store carbon (3)
▪ Climate – this affects the rate of plant growth and microbial activity. Decomposition occurs at a fast rate in places with higher temperatures and rainfall.
▪ Soil type – Clay rich soils contain more carbon than sandy soils.
▪ Use of soils – Land use, cultivation and disturbance can affect how much carbon can be held.
38
Describe the natural greenhouse effect (4)
- sunlight passes through the atmosphere and warms the earth
- infrared radiation is given off by the earth
- most escapes to outer space, allowing the earth to cool
- but some infrared radiation is trapped by gases in the air (including CO2) keeping the air warm enough to sustain life
39
Describe the proportions of inputs and outputs of the natural greenhouse effect (4)
- Around 31% of energy is reflected by clouds and gases in the atmosphere.
- The remaining 69% is absorbed by the Earth’s surface and oceans.
- 69% of surface absorption is reradiated to space as longwave radiation
- A large proportion of longwave radiation is radiated back to the Earth by clouds & greenhouse gases
40
Describe levels of atmospheric carbon prior to the industrial revolution
- Before The Industrial Revolution, the natural greenhouse effect was constant.
- The slow carbon cycle, volcanism, sedimentation have been fairly constant over the last few centuries.
- Natural exchanges between the slow and fast sections of the carbon cycle were relatively small.
- There were small variations in atmospheric CO2 up until the late 19th century.
41
How has human activity affected the greenhouse effect?
- Since the 1750s (when industrialisation began in the UK), global concentrations of greenhouse gases like CO2 & CH4 have increased by more than 25%.
- Since the 1980s, 75% of carbon emissions have come from burning fossil fuels.
- Human activities have led to more carbon being released into the atmosphere and less being absorbed
42
How does land use change affect levels of atmospheric carbon?
- Accounts for a tenth of carbon release annually and impacts on short-term stores in the carbon cycle, such as the soil and atmosphere.
- Farming Practices: In the Amazon, around 70% of deforestation is for cattle ranching. Cattle produce significant amounts of methane, further contributing to global warming. Scientists are considering whether feeding cows different foods would help to reduce their methane emissions.
43
How do fertilisers affect atmospheric carbon levels?
- Fertilisers are a significant source of greenhouse gases as well as rice paddy fields, from which methane emissions have increased as a result of increased productivity due to higher CO₂ levels.
- More sustainable grains and seeds like quinoa are being considered as substitutes, which require less water to grow
44
How does deforestation affect levels of atmospheric carbon?
- In total, deforestation accounts for about 20% of all global greenhouse emissions.
- The main impact is when the cycle is interrupted and the land is used for other purposes, which then reduces carbon sequestration and land becomes a carbon source rather than a carbon sink.
45
How does urbanisation affect levels of atmospheric carbon?
- This is the process of replacing countryside with buildings and other similar infrastructure.
- It affects the local and global carbon cycles, by replacing vegetation and covering soils.
- Urban areas occupy 2% of the world’s land mass, but these areas account for 97% of all human caused global CO₂ emissions.
- Cement is an important building material, but releases carbon dioxide during production, contributing 7% to global carbon dioxide emissions each year, so sustainable options for recycling concrete are being developed.
46
How does combustion of fossil fuels affect levels of atmospheric carbon?
- This results in CO2, sulphur and particulates being released into the atmosphere.
- If combustion occurs in a hot engine, NO2 will also be released (also a greenhouse gas) as nitrogen from the air fuses with oxygen.
- It is estimated that burning fossil fuels has added more than 180 Gt of carbon to the atmosphere.
47
How is solar energy distributed around the Earth's surface? (3)
- The amount of solar energy reaching the Earth varies depending on location, and is the main factor in determining climate temperatures.
- Solar intensity is more intense at the equator, and reduces as you travel towards the poles.
- The Albedo Effect will also determine the temperature of a location. Snow reflects solar radiation whereas dark forests absorb the most solar radiation.
48
Global distribution of impacts of the enhanced greenhouse effect (4)
● In Europe, average temperatures are expected to increase more than the global average.
● The largest increases are expected in Eastern and Northern Europe during winter and Southern Europe during summer.
● Annual precipitation is expected to increase in Northern Europe but decrease in Southern Europe.
● Extreme weather events are likely to increase in both frequency and intensity.
49
Describe the global distribution of convectional rainfall (4)
- Solar radiation is the most intense along the equator, so convectional rainfall is common and rainfall is generally very high.
- Where convectional rainfall is likely to occur can be understood using the ITCZ Model.
- Rainfall occurs at subtropical highs (mid-latitude) and the poles.
- Where air submerges and cools, water vapour condenses to form clouds and precipitation. Where air rises, the air heats up and moisture will evaporate. This creates dry weather conditions.
50
How might global warming affect certain species?
- Species with low population numbers are already at high risk. There is already evidence showing that there will be change in species’ population size, timing of reproduction and migration.
- Marine organisms are also at risk. They are threatened with low oxygen levels and high rates of acidification. The impact on coastal ecosystems and low lying areas of sea levels rising could continue.
51
Impacts of global warming on the Arctic (3)
- The arctic region is warming twice as fast as the global average.
- Melting permafrost releases methane and carbon dioxide which increases the concentration of greenhouse gases in the atmosphere.
- This could lead to further Global Warming and even more melting of snow and ice, establishing a positive feedback loop through a reduced Albedo effect.
52
Impacts of global warming on the Arctic tundra ecosystem (3)
- The Arctic tundra ecosystem has changed significantly; rapid warming has contributed to extensive melting of snow and ice during the summer months.
- Shrubs and trees which previously couldn’t live in the Arctic have began to grow.
- In Alaska, the Red Fox has now spread northwards and competes with the Arctic Fox for food and territory
53
Impacts of global warming on the hydrological cycle (5)
- Increased rate of evaporation could lead to more moisture being held in the atmosphere rather than in the ocean.
- Increase in surface permafrost temperatures.
- Less sea ice and glacier storage.
- Change in capacity of terrestrial ecosystems.
- Change in river discharge - increased risk of flooding in winter and droughts in summer.
54
Define energy security
Maximum energy security refers to the uninterrupted availability of energy sources at an affordable price.
55
What is the difference between long-term and short-term energy security?
- Long term energy security mainly deals with timely investments to supply in energy sources that will match economic developments and environmental needs.
- Short term energy security focuses on the ability of the energy system to react promptly to sudden changed in the balance between energy demand and energy supply.
56
How is energy security evaluated? (4)
● It is generally evaluated at a national level, countries are either energy secure or insecure.
● There are four aspects of supply: Availability, Accessibility, Affordability and Reliability.
● It requires an accurate prediction of future energy.
● Those countries that are most energy secure are those who can meet their energy demand using supply from within their boundaries.
57
What is energy security important for? (5)
- Most modes of transport
- Lights in towns and cities
- Heating homes
- Domestic appliances
- Necessary for most forms of manufacturing
58
What is energy consumption measured in?
- usually per capita
- Equivalent kilograms of oil per year (Kgoe/yr)
- Gigajoules per year (GJ/yr) or Exajoules (EJ/yr)
- Megawatt hours per year (Mwh/yr)
59
How is energy intensity measured?
- Energy Intensity is an alternative measure of how efficiently a country is using its energy, in units of energy used per unit of GDP.
- A high energy intensity indicates a high price or cost of converting energy into GDP.
- It is generally recognised that energy intensity decreases with development; energy is used more efficiently and so the cost per unit of GDP reduces.
60
Define energy mix
The energy mix refers to the range and proportion of energy produced by methods of production. These can include:
- Non-renewable fossil fuels like oil, gas and coal.
- Recyclable fuels like nuclear energy and general waste.
- Renewable energy like wind, solar and geothermal
61
What is the difference between primary and secondary energy sources?
- Primary energy sources produce energy by using a raw material
- secondary sources are modified primary energy sources which are easier to use e.g. oil into petrol and coal into electricity.
62
Describe global patterns of energy consumption
- Global energy consumption varies, but is generally higher in northern hemisphere countries, which are more developed
63
Roles of energy players (3)
▪ They explore, exploit and distribute energy resources.
▪ They own supply lines and invest in the distribution and processing of raw materials.
▪ They respond to market condition to increase the profits.
64
Reasons why TNCs are the most prominent energy players (3)
- Some TNCs have more economic value than a small country, enabling the company to take action and invest in large-scale projects that a country may not afford.
- TNCs can bypass political tensions and access sources otherwise restricted to other countries. In certain parts of the world, an MEDC trying to help to exploit an energy source in an LEDC could be seen as a direct threat to the LEDC.
- TNCs may be inclined to invest in local infrastructure, logistics and development of workers’ villages. This benefits all; the TNC benefits from faster transport links and a happier workforce, whilst the government receives ‘free’ investment.
65
Describe OPEC
- OPEC is an IGO that with member countries which export oil and petroleum.
- OPEC producers control 81% of the world’s discovered oil reserves.
- Their mission is to unify the petroleum policies of its members to ensure the stabilisation of oil markets.
66
Aims of OPEC (3)
- create an efficient and regular supply of oil to consumers.
- create a steady income for producers.
- create a fair return for those investing in the industry.
67
Criticisms of OPEC (5)
- In the past, OPEC set quotas depending on the condition of the world economy. Supplies were boosted when demand rose whilst supplies were cut if demand fell.
- Between 2012-2016, oil output was kept high to compete against the USA which produced vast amounts of oil through fracking.
- The flooding market caused a collapse in global oil prices.
- OPEC has also been accused of holding back production in order to increase prices and in turn increase profits for oil exporting nations.
- This can be detrimental to developing countries, who need vast, cheap amounts of oil to continue economic development and manufacturing.
68
Describe the role of national governments as energy players
- Governments try to secure energy supplies for their country and they also regulate the role of private companies.
- EU governments are trying to reduce CO2 emissions and reduce dependency on fossil fuels.
69
Describe the role of consumers as energy players
- Consumers create demand with purchasing choices usually based on price.
- As a country becomes richer and more educated, the population can change their shopping habits to reflect their needs: locally sourced, environmental friendly, reliable energy supply during winter and extreme weather.
- lots of energy companies now have tariffs on imported or non-renewable sources to reduce energy insecurities or carbon-offset their energy.
- money raised on non-renewable energy can fund environmental work such as afforestation, research into carbon capture and storage, etc
- If consumers change their spending habits and only use these tariffs then companies will be encouraged to move towards more green energy
70
How does human geography affect energy supply?
- Most countries are interdependent for energy sources - they import energy from other countries.
- This has geopolitical implications and requires the cooperation of other countries
- Any stage in the energy supply chain may be used by countries as a political tool, to cause or resolve tension between countries. Different countries have varying ‘national interests’.
71
Describe the energy supply chain
- Energy is produced in the areas where the physical geography is suitable
- Energy is either processed on site, or there may be no need for processing
- Energy is distributed by pipeline, transportation, or in the form of electricity
- Distribution methods may cross international borders, having geopolitical implications
72
Problems caused by fossil fuel supply
- There is a mismatch between the supply and demand for fossil fuels.
- This is largely due to inequality in wealth and development, natural resource supplies and industrialisation.
- Consumption of coal is declining worldwide, more than other fossil fuels.
- Over half of the world’s oil come from OPEC and North American nations.
- However, since Europe has the largest demand for oil but produces very little, oil must be transported and traded. This may cause further insecurity and tensions.
73
Describe energy pipelines
- Pipelines are efficient in carrying billions of m3 of oil across the world between countries.
- Many of these pathways depend on international agreements, so influence global politics.
74
Describe how oil is transported using oil tanker
- Around half of the world’s oil is transported using oil tanker though choke points (a key point in the logistics of energy, which can easily be disrupted).
- If choke points become blocked or threatened, then oil prices can rise very quickly and political tensions escalate.
- Ukraine is considered a choke point in the EU’s supply of oil - most pipelines from Russia run through Ukraine, and with increasing uncertainty in Ukraine relations with Russia, the EU’s supply could become increasingly insecure.
75
How can political conflict limit energy security?
- Conflicts and political altercations can severely limit energy security.
- For example, military conflict can destroy infrastructure which will restrict the flow of energy from source to use.
- Disagreements between nations can also limit energy security.
- This is the case for Russia, who have several political sanctions against them. As Russia is a major supplier to Europe, this has caused some shortages in electricity.
76
Why are alternative energy sources increasing in usage?
- Some alternative sources aim to increase supply of fossil fuels, keeping energy prices low and improving energy security.
- However, some new alternative sources aim to reduce CO2 and greenhouse gas emissions whilst still meeting demand.
77
Shale gas fracking - description
- Extracted through fracking, Shale Gas has received major environmental opposition.
- However, it provides 25% of the US’s energy needs in 2015.
- Fracking is relatively new process of extracting Shale gas. Water, chemicals and sand are pumped into the ground to break up the shale, access the hydrocarbons and force them to the surface.
- Horizontal drilling helps to remove the gas reserves.
78
Advantages of shale gas fracking (4)
● Less polluting than coal or oil
● Requires large amounts of water
● Could provide boost to the economy
● In the UK, the Royal Academy of Engineers believe we can make fracking safe
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Disadvantages of shale gas fracking (4)
● Wastewater needs treating due to chemical contents
● May pollute groundwater aquifers. In the USA the water has become flammable due to pollution by fracking
● Earthquakes of low magnitude may occur, though they are not usually strong enough to pose a risk to humans. They may damage fracking infrastructure, causing further leakages
● The IPCC suggest it would be irresponsible to use shale gas
80
Deep-water oil - description
- As oil supplies decrease, energy companies have begun extracting oil from deeper depths.
- Deep-water oil faces larger risks during extraction, and (similar to normal oil production) oil spills during transportation
81
Deep-water oil - advantages (4)
● Many engines and appliances are designed to operate on oil, therefore to continue to extract oil would avoid large changes to many important engines: vehicles, planes, etc.
● Shale gas produces half the emissions of coal, which would reduce global emissions without completely eradicating fossil fuel use.
● A large influx of readily available shale gas would drop the price of electricity.
● The majority of shale gas is found in the US, which would improve the US’s economy and provide an alternative source to Russian oil (if political tensions between UK and Russia continue, our energy security is at risk).
82
Deep water oil - disadvantages (2)
● Fracking faces large environmental opposition, especially as fracking can trigger minor tremors.
● Shale gas is still more expensive to produce than conventional gas.
83
Tar sands - description
- The extraction of petroleum from sands involves high energies and boiling water, which can leave ponds of concentrated chemicals.
- Tar sands have a large environmental cost, but can be lucrative in profit and employment opportunities.
84
Tar sands - advantages (2)
● Tar sand production creates economic growth and a large influx of jobs for rural regions.
● Fastest growing industry, producing the high-value bitumen for international exportation.
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Tar sands - disadvantages (3)
● The process of extracting bitumen is water and energy intensive, producing a large volume of waste (12 barrels or hot water produce 1 barrel of bitumen and 3 barrels of tailing pond waste).
● The liquid waste is left in tailing ponds, so water can be recycled after it separates from the clay and salts. However, tailing ponds may also contain sulfate, chloride and ammonia which may infiltrate the groundwater stores and other water sources.
● Open mining involves removing the top layer of vegetation and soils to access the bitumen-sands, destroying habitats.
86
Renewable energy - advantages
- Renewable energy is likely to be an important component of the future energy mix as it has a
low carbon footprint (in most cases), the technology is always improving and becoming more efficient.
- Each renewable resource has advantages and disadvantages , though as time progresses the disadvantages will decrease as the technologies are improved
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Renewable energy - disadvantages
All have the disadvantage of being visually unappealing and causing minor disturbances to the local environment.
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Solar power - description
Panels that convert the sun’s energy into electricity
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Solar power - advantages (2)
- Costs are decreasing rapidly
- Large potential in desert areas
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Solar power - disadvantages (2)
- Not very efficient yet (15-20%)
- Effectiveness dependent on climate and time of the year and day
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Wind power - description
Wind drives large turbines and generators that produce electricity
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Wind power - advantages (3)
- Low running costs
- Can be used year round
- Plenty of suitable sites
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Wind power - disadvantages (2)
- Bird life can be affected
- Weather dependent
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Wave power - description
Waves force a turbine to rotate and produce energy - or other similar method
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Wave power - advantages (2)
- Produce most electricity during winter when demand is highest
- Pioneer projects are commencing across the globe
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Wave power - disadvantages (2)
- Very expensive and a ‘perfect’ solution is yet to be created
- Needs to survive storms
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Tidal power - description
Incoming tides drive turbines in similar way to hydropower
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Tidal power - advantages (2)
- Has significant potential
- Reliable source of energy once installed
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Tidal power - disadvantages (3)
- Very expensive
- Few schemes currently operating in the world
- Impact on marine life
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Geothermal power - discription
Water is pumped beneath the ground to hot areas and the steam from the water drives turbines to produce electricity
101
Geothermal power - advantages (2)
- Low maintenance costs
- Suitable where other technologies might not be
102
Geothermal power - disadvantages (2)
- High installation cost
- Risk during earthquakes etc.
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Why is it unlikely that renewables will completely replace non-renewables? (3)
▪ Not all renewable energy sources provide the same amount of energy; you need more wind turbines than hydroelectric dams.
▪ Oil prices in 2015 dropped significantly and as renewables are generally more expensive, they became less attractive.
▪ Some forms of renewable energy have negative impacts e.g. HEP could lead to large swathes of land getting flooded.
104
Nuclear power - description
- Nuclear power is the use of nuclear reactions to produce electricity.
- can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions.
- considered to be a recyclable energy, since little Uranium is needed to produce large amounts of energy through fission
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Nuclear power - advantages (4)
- very low carbon footprint
- high efficiency
- may have fewer negative impacts than fossil fuels
- technology becoming more affordable and accessible for NICs
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Nuclear power - disadvantages and risks (5)
▪ Nuclear Disasters like Chernobyl and Fukushima (mainly due to mismanagement) could happen again
▪ The risk that nuclear powered stations may be infiltrated during conflict or by terrorists.
▪ Radioactive waste has to be disposed of safely, often through vitrification in underground caverns.
▪ The technology involved is only accessible for developed countries. Operational costs are quite low but construction and decommissioning costs are extremely high.
▪ Energy security may be compromised if countries own and fund nuclear plants in other countries
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Biofuels - description
- any kind of fuel manufactured from living things or from waste
- The process of burning biofuels is carbon neutral - CO2 taken in by a plant during photosynthesis will then be released during combustion.
108
Biofuels - advantages (6)
- Renewable energy source.
- Lower emissions (carbon neutral) than fossil fuels.
- Can be grown very easily
- Provides rural inward investment and local development projects.
- Positive multiplier effect.
- Fuel earns export income.
109
Biofuels - disadvantages (8)
- Deforestation for biofuels
- Takes land that food can be grown on.
- Requires fertilizers and pesticides.
- Requires large volumes of water
- Loss of carbon sinks as forest destroyed to make way for plantations.
- Biofuel production will reduce food production, leading to future insecurity.
- Water sources may become contaminated with chemicals.
- Where a biofuel source is also a food supply, food prices can increase when shortages occur.
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Describe carbon capture and storage (CCS)
- a technological strategy used to capture CO2 emissions from coal fired power stations.
- The gas collected from the power plant, compressed and stored into underground aquifers or disused mines.
- CCS could help to reduce carbon emissions by 19% but due to their cost, only 1 scheme exists currently
111
Describe hydrogen fuel cells
- Hydrogen fuel cells provides an alternative to the use of oil.
- Hydrogen is the most abundant element in the atmosphere but it usually combines with other elements especially carbon. Therefore Hydrogen needs to be separated and stored before use.
- Fuel cells convert chemical energy found in hydrogen into electricity and this produces pure water as a by-product.
- These fuel cells are much more efficient than petrol engines in vehicles.
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Causes of deforestation
- More than half of forested land is cleared due to increased demand for commodity production: soy, palm oil, beef and paper production.
- Land is also being converted to build dams and reservoirs, therefore land clearing may increase as energy demands increase or water supplies decrease.
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Impacts of deforestation on the carbon cycle (3)
▪ Reduction in carbon stored in biosphere.
▪ Reduction in carbon absorbed for photosynthesis.
▪ More carbon released from combustion.
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Regional trends in deforestation (4)
▪ 90% of forests in the UK and USA were lost through deforestation by the 19th century.
▪ Boreal forests have been threatened in Russia and Canada for oil and tar sands production.
▪ In Africa and South America, most forests have halved in area since the 1960s
▪ In Indonesia, large areas of forest land have been cut down or burnt to make way for palm oil plantations for which demand is increasing significantly
115
Describe the two types of grassland
- Temperate grasslands which have no trees
- Tropical grasslands or Savannahs which have trees but infertile soil
116
Roles of grasslands (5)
● Traps moisture and floodwater
● Absorb toxins from soil
● Provide cover for dry soils
● Provides habitats for wildlife
● Act as a carbon sink
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Impacts on carbon cycle of converting grasslands to farmland (3)
- Release CO2 into atmosphere initially.
- There is a net increase in CO2 emissions as biofuel crops need fertilisers.
- Cultivated soil is more susceptible to erosion.
118
Benefits of mangrove forests (4)
- stabilising coastlines against erosion
- collecting nutrient-rich sediments trapped between the entangled prop roots
- providing protection and shelter against extreme weather (e.g. storm winds and floods) and tsunami, by absorbing and dispersing surges
- providing nurseries for coastal fish away from predators
119
Why is overfishing a threat to some communities? (4)
- Fishing supports 500 million people of which 90% live in LDCs.
- Fish is a cultural choice for wealthy MEDCs where as it is a necessity for people in LEDCs.
- Millions of small-scale fishing families depend on seafood for their income as well as for food.
- In addition to fishing, many countries rely on their marine life to attract tourism
120
Impacts of global warming on coral reefs
- As oceans become more acidic, corals cannot absorb alkaline CaCO3 in order to maintain their skeletons, in turn reefs begin to dissolve.
- Algae provide food to corals through photosynthesis. If the water becomes warm enough, the algae leave the coral, leaving the coral to turn white (Coral bleaching)
121
Benefits of coral reefs (4)
- Shelter 25% of marine species
- Protect shorelines
- Support fishing industries
- Provide income through tourism
122
Impacts of climate change on the water cycle and climate (4)
- More frequent and more intense storms and hurricanes.
- Rising sea levels, therefore more coastal erosion and some land lost (isostatic sea level rise).
- More frequent floods, droughts and heatwaves.
- Changes in ocean currents and atmospheric circulation could have an impact on patterns of precipitation, evapotranspiration and temperature.
123
Impacts of global warming on the carbon cycle (5)
- More CO2 being released from boreal forests as they become drier and forest fires start.
- methane from thawing permafrost.
- methane from the destabilization of wetlands.
- Loss of Arctic Albedo may lead to increased permafrost thawing.
- If some arctic bogs thaw, huge quantities of methane and CO2 gas will be released into the atmosphere, leading to irreversible changes to climate.
124
Describe the Albedo effect
- white snow reflects solar radiation, earth and dark surfaces will absorb solar radiation
- this explain the temperature of the Arctic
125
Predictions for future climate change
- Greenhouse gases are likely to increase in the future as more countries industrialise and develop.
- Greenhouse gases remain in the atmosphere for a long time and so even if global emissions were reduced, surface air temperatures would still continue to increase.
126
Physical factors creating uncertainty over climate change (3)
● Oceans and forests are carbon stores.
● Oceans take a very long time to respond to changes in greenhouse gas concentrations.
● Weather will have a direct influence over vegetation productivity and the rate of chemical reactions. As how climates will change is unknown, future vegetation changes is also unknown.
127
Human factors creating uncertainty over climate change (3)
- economic growth
- population change
- technology and globalisation
128
Describe the positive feedback mechanism in Peatlands
- Peat is the accumulation of partly decayed vegetation, which stores a large amount of carbon.
- Warming causes peat to dry out and the rate of decomposition increases.
- Peatlands emit carbon in the form of methane which increases greenhouse gases and accelerates enhanced Greenhouse Effects.
129
Describe the positive feedback mechanism of melting permafrost
- When permafrost melts, trapped carbon is released into the atmosphere as CO2 and methane which increases greenhouse gas concentrations in the atmosphere.
- This leads to higher temperatures and further melting of ice.
130
Define a climate tipping point
A climate tipping point is a critical threshold; when this threshold is reached, small changes in the global climate system can transform a stable system irreversibly.
131
Describe the Amazon tipping point
- Rainfall in the Amazon is largely recycled. If there is a drought in the rainforest, trees may die.
- A tipping point could be reached when moisture can no longer be recycled (due to too few trees to intake moisture) which leads to more trees dying.
132
Describe a boreal forest tipping point
- In the boreal forest ecosystem, hot and dry summers lead to water stress which can result in a loss of trees.
- A tipping point could be reached when trees no longer absorb much CO2 which in turn increases the concentration of greenhouse gases in the atmosphere, leading to further dry summers.
133
Describe the thermohaline circulation tipping point
- Cold water in the North Atlantic forms part of the thermohaline circulation.
- To keep warm water heading from the tropics towards Britain, heavy water must sink in the North.
- The melting of Northern ice sheets releases large amounts of fresh water into the ocean which is less dense and has low salinity.
- This will disrupt the circulation of water, affecting the temperature of the water reaching the ocean and in turn the weather of the UK.
- It is believed by some scientists that the thermohaline circulation is slowing down. If it stops then the world will go into another ice age
134
Examples of adaptation strategies against climate change (4)
- water conservation and management
- land use planning and flood risk management
- resilient agricultural systems
- solar radiation management
135
How is Israel conserving and managing water?
- smart irrigation
- recycling sewage for agricultural use
- reducing agricultural consumption and importing water in food as virtual water
- adopting stringent conservation techniques
- managing demand by charging 'real value' prices for water to reflect the cost of supply and of ecosystem management
136
Describe land-use planning and flood-risk management
- land-use zoning is a technique used for flood management, where development on flood plains in limited to low-impact things like playing fields and parks
- low-cost approach to flood management
- infiltration occurs naturally and surface runoff is reduced along with the risk of wider flooding
137
Describe conservation cropping
- resilient agricultural system that is growing in use
- involves growing crops using a no-tilling (ploughing) approach
- it uses fewer fertilisers, retains stubble, and grows cover crops
- benefits include increased yields and incomes for farmers, plus improved soil structure, healthier soils, water conservation, and erosion control
138
Describe solar radiation management
- this is a form of climate engineering, which aims to reflect solar ray and so reduce global warming
- examples include sulphur aerosols into the upper atmosphere, cloud brightening, and space-based reflectors
- advantages: can be deployed relatively quickly, offset the effects of some greenhouse gases
- disadvantages: uncertainty about effectiveness, ethical social and political issues, potentially expensive, would have to be continued forever
139
Examples of mitigation strategies against climate change (5)
- carbon taxation
- energy efficiency
- afforestation and reforestation
- renewable switching
- carbon capture storage
