1
Q
What is the carbon cycle?
A
The biogeochemical cycle by which carbon moves from one sphere to another. It acts as a closed system made up of linked subsystems that have input, throughputs and outputs.
2
Q
What stores is carbon present in?
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 organisms
3
Q
Why is carbon important?
A
- regulates climate
- provides major building blocks for life on earth
4
Q
What is carbon storage measured in?
A
Petagrams Pg
5
Q
What are residence times?
A
The average length of time that material spends in a given pool
6
Q
What are fluxes?
A
Fluxes refer to the movement/transfer of
carbon between stores.
7
Q
Carbon store: Marine sediment and sedimentary rock
A
Easily the biggest store. 66,000 - 100,000 million billion metric tons of carbon. The rock cycle and continental drift recycle the rock over time, but this may take thousands, if not millions of years.
8
Q
Carbon store: Oceans
A
The second biggest store contains a tiny fraction of the carbon of the largest store. 38,000 billion metric tons of carbon . The carbon is constantly being utilised by marine organisms, lost as an output to the lithosphere, or gains as an input from rivers and erosion.
9
Q
Carbon store: Fossil fuel deposits
A
Fossil fuel deposits used to be rarely changing over short periods of time, but humans have developed technology to exploit them rapidly, though 4000 billion metric tons of carbon remain as fossil fuels.
10
Q
Carbon store: soil organic matter
A
The soil can store carbon for over a hundred years, but deforestation, agriculture and land use change are affecting this store. 1500 billion metric tons of carbon stored.
11
Q
Carbon store: atmosphere
A
Human activity has caused CO ₂ levels in the atmosphere to increase by around 40% since the industrial revolution , causing unprecedented change to the global climate. 750 billion metric tons of carbon stored.
12
Q
Carbon store: terrestrial plants
A
Vulnerable to climate change and deforestation and as a result carbon storage in forests is declining annually in some areas of the world. 560 billion metric tons of carbon.
13
Q
What is the geological carbon cycle?
A
- Very long turnover rate over 100,000 years
- Organic matter that is buried in deep sediments, protected from decay, takes millions of years to turn into fossil fuels. Carbon is exchanged with the fast component through volcanic emissions of CO2, chemical weathering, erosion, and sediment formation on the sea floor.
14
Q
What is the biological carbon cycle?
A
- Carbon is sequestered in, and flows between, the atmosphere, oceans, oceans sediments, and on land in vegetation, soils and freshwater.
- relatively large exchange fluxes and rapid turnover rates
15
Q
How is oil and natural gas formed?
A
Formed from the remains of tiny aquatic animals and plants. Gas and oil occur in pockets in rocks, migrating up through the crust until meeting caprocks. Natural gas, such as methane, is made up of the fractions of oil molecules, so small they are in gas form not liquid, usually found with crude oi. Other carbon deposits include oil shales, tar sands and gas hydrates.
16
Q
How is coal formed?
A
Formed from the remains of trees, ferns and other plants. There are four main types:
- anthracite - the hardest coal, with the most carbon and therefore a higher energy content
- bituminous coals - second in hardness and carbon content
- soft coals such as lignite and brown coal are lower in carbon and energy potential; these are the major global source of energy supplies but emit more CO2 than hard coals
- peat is the stage before coal, an important carbon and energy source
17
Q
What is lithification?
A
where freshly deposited loose grains of sediment are converted into rock
18
Q
What is decomposition?
A
the breakdown of animals and plant structures by bacteria and the release of carbon compounds into the atmosphere, soil and to the ocean floor. Plants and animal particles from decomposition store carbon
19
Q
What geological processes release carbon?
A
- Volcanic outgassing
- Chemical weathering
20
Q
Explain volcanic outgassing
A
- Disturbance by volcanic eruptions or earthquake activity may allow pockets of CO2 that exist in the earths crust to be released into the atmosphere.
- Volcanoes currently emit 0.15-0.26 Gt CO2 annually, compared to humans emitting about 35 Gt annually, mainly from fossil fuel use, so volcanic degassing is relatively insignificant.
- An example of major degassing as a pulse is the 1991 eruption of Mt Pinatubo in the Philippines.
21
Q
Where does outgassing occur?
A
○ Active or passive volcano zones associated with tectonic plate boundaries including subduction zones and spreading ridges
○ Places with no current volcanic activity such as the hot springs and geysers in Yellowstone National Park USA
○ Direct emissions from fractures in the earth’s crust
22
Q
Explain chemical weathering
A
- The geological aspect of the carbon cycle interacts with the rock cycle.
- The processes through which the materials of the earth change can be broken down into 5 phases
- Chemical weathering - acid rain, formed from water reacting with atmospheric CO2 making carbonic acid, reacts with surface minerals, dissolving them into their component ions
- Transportation of calcium ions by rivers from the land into the oceans - the calcium ions combine with bicarbonate ions forming calcium carbonate and precipitate out as calcite and other materials
- Deposition and burial turns the calcite sediment into limestone
- Subduction occurs
- Some carbon rises to the surface within heated magma, then is “degassed” as CO2 and returned to the atmosphere. This is proved by diamonds (the purest form of carbon) being discovered to be formed up to 700km deep, proving that carbon is cycled between the earth’s surface and the lower mantle.
- The processes through which the materials of the earth change can be broken down into 5 phases
23
Q
What is carbon sequestration?
A
Carbon Sequestration is the transfer of carbon from the atmosphere to other stores in solid or liquid form and can be both natural and artificial.
24
Q
Why is photosynthesis important to the carbon cycle?
A
Living organisms convert Carbon Dioxide from the atmosphere and Water from the soil, into Oxygen and Glucose using Light Energy. By removing CO₂ from the atmosphere, plants are sequestering carbon and reducing the potential impacts of climate change.
25
Why is respiration important to the carbon cycle?
Respiration occurs when plants and animals convert oxygen and glucose into energy which then produces the waste products of water and CO₂. Overall, plants absorb more CO₂ than they emit, so are net carbon dioxide absorbers (from the atmosphere) and net oxygen producers (to the atmosphere).
26
What is the biological carbon pump?
- Phytoplankton photosynthesise, taking in carbon and forming organic matter.
- When they get eaten, carbon is passed through the food chain. CO2 is released back into the water as these organisms respire.
- Dead plankton sinks to the ocean floor, where it either decomposes or is turned into sediment
27
What is the carbonate pump?
- Marine organisms use calcium carbonate to make shells and inner skeletons.
- When these organisms die and sink, many shells dissolve before reaching sea floor sediment, so this carbon becomes part of deep ocean currents
- Shells that do not dissolve build up on the sea floor, forming limestone sediments
28
What is the physical pump?
-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.
- However, oceanic circulation provides a constant source of new water on the surface while transferring surface water into the deep ocean. It is this process which enables the ocean to store so much carbon. Water is not stored evenly within the water; the colder the water, the more CO2 is absorbed so the concentration of CO2 in the ocean is different around the world.
29
What is 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. In addition to this, 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.
1, The main current begins in polar oceans where the water is very cold, surrounding seawater sinks due to a higher density.
2. The current is recharged as it passes Antarctica by extra cold, salty, dense water.
3. Division of the main current; northward into the Indian Ocean and into the Western Pacific.
4. The two branches warm and rise as they travel northward then loop back southward and
westward.
5. The now warmed surface waters continue circulating around the globe. On their eventual return to the North Atlantic they cool and the cycle begins again.
30
How does ocean temperature affect rate of 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 carbon dioxide). This would accelerate Climate Change and lead to further ocean warming (positive feedback mechanism).
31
What is the enhanced greenhouse effect?
The enhanced greenhouse effect is the impact on the climate from the additional heat retained due to the increased amounts of carbon dioxide and other greenhouse gases that humans have released into the earths atmosphere since the industrial revolution.
32
How does the enhanced greenhouse effect work?
When the sun releases radiation towards the earth, some of it is absorbed by the earth's surface, causing temperatures to increase. Some of it however, is reflected back towards the atmosphere. Greenhouse gases produced by humans trap this radiation and prevent it escaping, reflecting it back onto the earth's surface. This causes global temperatures to increase more than expected and leads to global warming.
33
What are the causes of the enhanced greenhouse effect?
- CO2 released from burning fossil fuels
- Methane from rice and cattle farming
- Nitrous oxide from fertilisers and jet engines
- Halocarbons from industry and solvents
34
Examples of feedback in the carbon cycle
VANISHING ARCTIC ICE - temp rises, arctic sea ice melts, reflective ice reduced, replaced with darker oceans which absorb more heat, so temp rises more
RAINFOREST CLEARANCE - temp rises, clearance decreases rainfall storage, leads to drought/wildfires, leading to less rainfall to maintain hydrological cycle, fire releases CO2 in vegetation into atmosphere, causing temp rise
35
Why is soil important?
* Without carbon, the nutrient and water cycles cannot operate properly
* The amount of carbon stored depends on the system -
○ Amount of carbon stored within soil = inputs (plant litter and animal waste) - outputs (decomposition, erosion and uptake in plant growth)
* Healthy soils usually -
○ Are dark, crumbly and porous
○ Contain many worms and other organisms
○ Provide air, water and nutrients for micro-organisms and plants to thrive
○ Contain more carbon or organic matter
○ Sequester carbon
○ Improve resilience to wetter weather as they enable infiltration and percolation of water
○ Retain moisture, which regulates soil temperature during heatwaves and reduces the effects of drought
36
What is Arctic amplification?
Arctic amplification is the phenomenon where the arctic region is warming twice as fast as the global average. Melting permafrost releases CO2 and CH4, increasing the concentration of greenhouse gases in the atmosphere and leading to increases global temperatures and further melting.
○ Climate change is altering the arctic tundra ecosystem. Rapid warming has contributed to extensive melting of sea ice in summer months, and greatly reduced snow cover and permafrost.
○ Shrubs and trees have started to establish themselves, as well as animals.
○ Not all scientists agree that melting permafrost will release stored carbon as carbon dioxide and methane
§ Some studies show that as permafrost thaws, the stored carbon remains in the soil and is used by new vegetation
§ Warmer temperatures accelerate decomposition, releasing carbon and nutrients
§ Nutrients encourage plant growth and the removal of carbon from the atmosphere through photosynthesis
37
What is energy security?
Energy security is achieved when there is an uninterrupted availability of energy at a national level and at an affordable price. All countries seek to achieve this; the most secure energy situation is where the national demand for energy can be completely satisfied by domestic sources. The more a country demands on imported energy, the more it is exposed to risks of an economic and geopolitical kind. Four key aspects of energy security are:
* availability
* accessibility
* affordability - competitively priced energy supply
* reliability - uninterrupted
37
Why is energy security important?
The importance of energy security stems from the fact that energy is vital to the functioning of a country. For example, it: powers most forms of transport, lights settlements, is used by some types of commercial agriculture; warms/cools homes and powers domestic appliances; is vital to modern communications; drives most forms of manufacturing.
38
How is energy consumption measured?
1. in per capita terms, i.e. as kilogrammes of oil equivalent or megawatt hours per person. In general, this measure rises with economic development
2. by a measure known as energy intensity, which is assessed by calculating the units of energy used per unit GDP. The fewer the units of energy, the more efficiently a country is using its energy supply. In general, energy intensity values decrease with economic development
39
What is the energy mix?
The energy mix is the combination of different energy sources used to meet a country's total energy consumption. It's an important part of energy security, and varies from country to country. There are distinctions between:
* domestic and foreign sources
* primary and secondary sources
○ primary = found in nature, not converted/transformed. It can be renewable (water/wind/sunlight) or non-renewable (coal/oil/gas)
○ secondary = derived from transformation of conversion of primary sources, usually more convenient (electricity)
40
What factors affect per capita energy consumption?
* physical availability
* cost
* standard of living
* environmental priorities (of governments)
○ for some, energy policy will be taking the cheapest route to meeting the nation's energy needs, regardless of the environmental costs. Others will seek to increase their reliance on renewable sources of energy; wile still other will have in place policies that raise energy efficiency and energy saving
* climate
○ Very high levels of consumption in North America, the Middle East and Australia reflect the extra energy needed to make the extremes of heat and cold more comfortable
* public perception
○ for some consumers, energy is perceived almost as a human right and therefore to be used with little or no regard for the environmental consequences. Others give priority to minimising the wastage of energy and maximising security
* economic development
* technology
41
What is the relationship between economic development and energy consumption per capita?
* Economic developments like infrastructure projects etc cause more demand for energy, which increases consumption.
* As a nation becomes more developed, they are able to obtain more energy, which will cause more energy to be used.
* The ability to obtain more energy facilitates more infrastructure projects, causing exponential growth of energy consumption relative to economic development
42
What are energy pathways?
The route taken by any form of energy from its source to its point of consumption. The routes involve different forms of transport, such as tanker ships, pipelines and energy transmission grids.
43
Energy player - TNCs
* Nearly half of these are state owned - all or in part - and thus under government control, therefore strictly speaking, aren't TNCs.
* Most are involved in a range of operations: exploring, extracting, transporting, refining and producing petrochemicals.
* E.G. Sinopec, BP, Royal Dutch Shell, PetroChina, Exxon Mobil
44
Energy player - OPEC
* Made up of 13 member countries which collectively control about 2/3 of the world's oil reserves.
* It is in a position to control how much oil and gas enters the global market, as well as the prices of both commodities.
* It has been accused of holding back production in order to drive up oil and gas prices.
* Algeria, Angola, Congo, Equatorial Guinea, Gabon, Iran, Iraq, Kuwait, Libya, Nigeria, Saudi Arabia, United Arab Emirates, Venezuela
44
Energy player - energy companies
* These companies are important as they convert primary energy (oil, gas, water and nuclear) into electricity, and then distribute it.
* Most companies are involved in the distribution of both gas and electricity.
* They have considerable influence when it comes to setting consumer prices and tariffs.
E.G. British Gas, EDF, Scottish Power
45
Energy player - consumers
* The most influential consumers are transport, industry and domestic users.
* They are largely passive players when it comes to fixing energy prices.
46
Energy player - governments
* They are the guardians of national energy security.
* They can influence the sourcing of energy for geopolitical reasons.
47
What is the problem with fossil fuel distribution?
There is a mismatch between where fossil fuels are found and where demand is greatest
48
Energy pathway - 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.
49
Energy pathway - chokepoints
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.
50
How can political conflict affect 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.
51
Unconventional fossil fuels - tar sands
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.
Benefits -
- greater energy security
- less reliance on other countries
Costs -
- energy intensive
- carbon emissions rise
- destroys forest and peat bogs - habitat loss
52
Unconventional fossil fuels - deep water oil
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.
Benefits -
- energy independence
- economic growth
- increased oil production
Costs -
- energy intensive
- increased risk of oil spills
- high cost
53
Unconventional fossil fuels - shale gas
Extracted through fracking, Shale Gas has received major environmental opposition. Fracking is the 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.
Benefits -
- less emissions than coal
- could boost economy
- more available reservoirs globally
Costs -
- prone to accident/leakage
- can cause earthquakes
- environmental degradation
- water contamination
54
Unconventional fossil fuels - oil shale
Oil shale is the rock from which shale oil is extracted. Shale oil is extracted by heating oil shale to between 60 and 160°C. It can be done underground or after the oil shale has been mined. High pressure hydrogen is used to remove impurities when heating.
Benefits -
- can be stored until oil prices rise
Costs -
- CO2 emissions
- requires huge amount of water
- pollutes drinking water
- causes earthquakes
55
Fossil fuel alternatives - nuclear
Nuclear energy can be used to create electricity, but it must first be released from the atom. In the process of nuclear fission, atoms are split to release that energy. It provides about 15% of the world's energy.
Benefits -
- can power millions of homes 24/7
- cheap once running
- little uranium needed to produce massive power
- does not produce CO2
- small land footprint
Costs -
- risk of accident
- high initial cost
- expensive to dispose of toxic waste
- uranium ore limited in crust
56
Fossil fuel alternatives - solar
Panels that convert the sun’s energy into electricity
Benefits -
- Costs are decreasing rapidly
- Large potential in desert areas
Costs -
- Not very efficient yet
- Effectiveness dependent on climate and time of the year and day
57
Fossil fuel alternatives - wind power
Wind drives large turbines and generators that produce electricity
Benefits -
- Low running costs
- Can be used year round
- Plenty of suitable sites
Costs -
- Bird life can be affected
- Weather dependent
58
Fossil fuel alternatives - wave power
Waves force a turbine to rotate and produce energy - or other similar method
Benefits -
- Produce most electricity during winter when demand is highest
- Pioneer projects are commencing across the globe
Costs -
- Very expensive and a ‘perfect’ solution is yet to be created
- Needs to survive storms
59
Fossil fuel alternatives - tidal power
Incoming tides drive turbines in similar way to hydropower
Benefits -
- Has significant potential
- Reliable source of energy once installed
Costs -
- Very expensive
- Few schemes currently operating in the world
- Impact on marine life
60
Fossil fuel alternatives - geothermal
Water is pumped beneath the ground to hot areas and the steam from the water drives turbines to produce electricity
Benefits -
- Low maintenance costs
- Suitable where other technologies might not be
Costs -
- High installation cost
- Risk during earthquakes
61
Fossil fuel alternative - biofuels
The process of burning biofuels is carbon neutral - CO2 taken in by a plant during photosynthesis will then be released during combustion.
Benefits -
- Low emissions
- Positive multiplier effect
- Easily grown
Costs -
- clearing land to grow biofuels creates food insecurity
- water contamination
- forest removal means carbon sink loss
62
Carbon capture and storage
Carbon Capture and Storage (CCS) is a technological strategy used to capture CO2 emissions from coal fired power stations. The gas collected from the power plant is 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.
63
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.
64
Why are forests important?
Forests cover around 30% of the Earth’s land area. Forests intercept rainfall and increase groundwater storage. A loss of even a small number of trees can disrupt weather patterns which could lead to more intense flooding and droughts. 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. By 2015, 30% of all global forests had been cleared. Annually, around 13 million hectares are lost every minute.
65
How does deforestation impact the carbon cycle?
▪ Reduction in carbon stored in biosphere.
▪ Reduction in carbon absorbed for photosynthesis.
▪ More carbon released from combustion.
66
Why are coral reefs important?
- Shelter 25% of marine species
- Protect shorelines
- Support fishing industries
- Provide income through tourism
67
How does climate change impact the carbon cycle?
- More CO2 being released from boreal forests as they become drier and forest fires start.
- CH4 from thawing permafrost.
- CH4 from the destabilization of wetlands.
- Loss of Arctic Albedo (white snow reflects solar radiation, earth and dark surfaces will absorb solar radiation) 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.
68
How does forest loss impact well being?
- Burning forests to create land for palm oil plantations releases huge amounts of carbon into the atmosphere
- Indigenous people driven away from forest by the actions of palm oil producers
- Loss of biodiversity (they are home to 80% of global biodiversity) - species such as orangutan, Borneo elephant and Sumatran tiger highly endangered
69
Why are forests important ecosystems? (ie what services do they provide)
Provisioning services - food production, water, wood, fuel
Supporting services - nutrient cycling, soil formation, habitat provision
Regulating services - climate, flood regulation, water purification
70
What does the environmental Kuznets curve show?
Societies are beginning to reach a tipping point, where environmental exploitation turns into environmental protection as income increases
71
How does deforestation impact the water cycle?
* Infiltration is decreased.
* Runoff and erosion are increased.
* Flood peaks are higher and the lag time is shorter.
* Increased discharge leads to flooding.
* More eroded material is carried in the river, both as bed load and as silt and clay in suspension.
72
How does deforestation impact soil health?
* impact washes finer particles of clay and humus away.
* Coarser and heavier sands are left behind.
* CO2 released from decaying woody material.
* Biomass is lost, due to reduced plant growth/photosynthesis
* Rapid soil erosion leads to a loss of nutrients.
* Increased leaching (the loss of nutrients from the soil by infiltration) means that minerals are lost.
73
How does deforestation impact the atmosphere?
* Turbulence is increased as the heated ground induces convectional air currents.
* Oxygen content is reduced and transpiration rates are lower.
* Reduced shading leads to more direct sunlight reaching the forest floor.
* Reduced evapotranspiration makes it less humid.
* The air is dryer (as above).
* Evapotranspiration rates from the resultant grasslands are about one-third that of the tropical rainforest.
73
How does deforestation impact the biosphere?
* Evaporation from vegetation is reduced.
* Less absorption of CO2 means a reduced carbon store
* Species diversity is reduced (e.g. less-resilient forest plants die off).
* Ecosystem services are reduced
* The decrease in habitats means that fewer animal species survive.
* Biomass is lost, because of reduced plant growth /
photosynthesis.
74
How much global land area does grassland cover?
26%
75
What is the role of grasslands?
● Traps moisture and floodwater
● Absorb toxins from soil
● Provide cover for dry soils
● Provides habitats for wildlife
● Act as a carbon sink
76
How does grassland conversion impact the carbon cycle?
- Converting grasslands into agricultural farms will 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.
77
What is ocean acidification?
- the decrease in pH of the Earth's oceans caused by the uptake of carbon dioxide from the atmosphere
- Ocean acidification involves a decrease in the alkalinity/pH of oceans, caused by the uptake of carbon dioxide from the atmosphere, released by burning fossil fuels. It occurs because oceans are a carbon sink (absorbs more carbon from the atmosphere than it releases). Absorbed carbon combines with water to form carbonic acid, releasing hydrogen ions. Water therefore is more acidic.
78
What are the impacts of ocean acidification?
- Shells built by animals like coral are thinner and more fragile.
- Acidification increases the risk of marine ecosystems reaching a critical threshold of permanent damage.
79
How much has the pH of surface seawater decrease since the Industrial revolution?
0.1, a 30% drop
80
What is happening with coral reefs?
○ Coral reefs, an important component of ocean life, stop growing when the pH is less than 7.8.
- The situation is now approaching the point that there is a real risk of some marine ecosystems and their goods and services passing the critical threshold of permanent damage. In the case of coral reefs, they are also being threatened by the rise in surface water temperatures. The widespread bleaching of the Great Barrier Reef of Australia is a clear indication that this threat has become a reality.
81
Why are droughts increasing?
Climate change -
○ Caused by increasing air temp due to GHG emissions. More moisture evaporates from land and lakes
○ Warmer temp also increase evaporation in soils - affects plant life and further reduces rainfall
○ Drier soils absorb less water, increasing flood risk
82
What are the biggest threats to forests?
- Land use changes (deforesting, converting grassland/forest to farmland, urbanisation)
- Economic development - driving deforestation for wood, land, fuel, minerals
- Growing palm oil, soya, biofuels etc
83
How do people oppose forest loss?
Many people join pressure groups like Greenpeace and the WWF to oppose forest loss. Greenpeace found that TNCs don't do enough to prevent deforestation, forest fires and human rights abuses.
84
How much has UK forest cover reduced by?
- After centuries of deforestation, the forest cover of the UK had been reduced from an estimated original figure of 80% to less than 10% by the end of the 19th century.
85
What is Arctic albedo?
Sunlight that was previously reflected back into space by the white surface is now being increasingly absorbed by the ever darkening land surface. In other words, it is encouraging further climate warming.
86
How does climate change's impacts on the Arctic affect human wellbeing?
In terms of human wellbeing, there has been both positives and negatives. The warming climate is opening up previously ice-bound wilderness areas to tourism. the exploitation of mineral resources, particularly Arctic oil and gas, is becoming more feasible. However, climate warming is disrupting and perhaps annihilating traditional ways of life, for example the fishing and hunting of Inuits in North America and the Sami reindeer herders of northern Eurasia.
87
What is the feedback loop with permafrost melt?
As permafrost thaws, organic matter in permafrost decays, releasing large quantities of methane into the atmosphere.
This feeds greenhouse effect - leads to even more warming
88
What are the effects of declining ocean health?
The decline in ocean health caused by acidification and bleaching is resulting in changes to marine food webs. In particular, fish and crustacean stocks are both declining and changing their distributions. Such changes are being particularly felt by developing countries.
- the FAO estimates that fishing supports 500 million people, 90% of whom live in developing countries
- Millions of fishing families depend on seafood for income as well as food.
- Seafood is also the dietary preference of some wealthier countries, notably Iceland and Japan.
- The tourism industry is threatened.
89
Why is there uncertainty about the role of carbon sinks?
* Oceans warming - warmer oceans can't absorb as much carbon dioxide
- Ocean acidification - could become saturated
90
Why is there uncertainty about population growth?
* Potential extra billion consumers by 2050 due to increasing affluence in emerging economies.
* Changing diets and increasing mobility increases emissions
* Increasing urbanisation, more fossil fuels
91
Why is there uncertainty about economic growth?
– There is a correlation between economic growth and energy consumption. After the financial crisis in 2007, there was concern that CO2 emissions would begin to rise as GDP growth picked up.
- Can economic growth be sustained?
92
Why is there uncertainty about energy sources?
* Energy consumption is increasing (by 2% between 2008 and 2014) however renewables make up 2/3 of increase in energy production in 2015
* What is the policy? With the harnessing of alternative energy sources - will fossil fuels be completely replaced?
93
Why is there uncertainty about permafrost melting?
* Melting permafrost releases trapped carbon into the atmosphere as CO2 and methane, which increases atmospheric greenhouse gas concentrations - leading to increased temperatures and melting (positive feedback)
94
Why is there uncertainty about forest die back?
* Tipping point could be reached where the trees will no longer absorb enough CO2,
* Tipping point could be reached where the level of die back actually stops the recycling of moisture within the rainforest which results in further die back.
- But as Arctic climate changes, boreal forest may grow further north, expanding forest carbon sink?
95
Why is there uncertainty about methane hydrates?
* Methane can be stored as crystals - if oceans warm, theoretically hydrates could come out of crystallised form and be released as gas
96
Why is there uncertainty about ocean circulation?
* The melting of the northern ice sheets releases significant quantities of freshwater into the ocean, which is lighter and less saline which blocks and slows the conveyor belt.
97
What are some tipping points?
* Melting glaciers, ice caps and sea ice, so that less heat is reflected out to space
* Ice cap melting increasing the flow of fresh water into the Arctic will collapse the Gulf Stream
* Forests will no longer absorb carbon, but become a source.
* Methane hydrates held in the mud under the sea begin to be released
* Melting permafrost releases vast quantities of methane
* Drought kills the Amazon forest and its carbon sink is released
* Bush fires increase the carbon load and reduce the storage capacity of forests
* As oceans warm the seas absorb less carbon
98
What is the Kyoto Protocol 1997?
An international agreement which aimed to cut GHG emissions by 5% by 2012.
It had mixed successes -
* Paved the way for new rules and measurements on low carbon legislation.
* By 2012 emissions were 22.6% lower than 1990 levels, however 2015 showed a 65% increase above 1990 levels, driven by China and India
* Only industrialised countries were asked to sign, not developing nations. The top emitters - USA and China - were left out of the agreement
99
What is the Paris agreement 2015 (COP21)
The Paris Agreement sets out a global framework to avoid dangerous climate change by limiting global warming to well below 2°C and pursuing efforts to limit it to 1.5°C
* All countries were involved
* The Agreement now has 140 national signatures. Among the more reluctant signatories are the three largest producers of GHGs: China, India and the USA (withdrew in 2017)
* Should be considered a limited success because pledges should reduce emissions from 60 gigatons per year to 55 by 2030, however needs to be about 40 to limit warning to 1.5C
100
Explain water conservation and management (adaptation)
Countries such as Israel with limited freshwater supplies used these strategies to adapt-
* Smart irrigation (Smart irrigation technology uses weather data or soil moisture data to determine the irrigation need of the landscape.)
* Recycling sewage water 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
101
What are the benefits/costs of water conservation and management?
Benefits
* Reduces water shortage frequency
* Saves energy needed to filter/heat water
* Fewer resources used, less groundwater abstraction
Costs
* Efficiency and conservation cannot match increased demands for water
* Changing cultural habits of a large water footprint needs promotion and enforcement by governments, e.g. smart meters
102
Explain resilient agricultural systems
* Climate-resilient agriculture (CRA) is an approach that includes sustainably using existing natural resources through crop and livestock production systems to achieve long-term higher productivity and farm incomes under climate variabilities.
* Conservation cropping it growing in use in places such as the USA, Syria and Iraq. It involves growing crops using a no tilling (ploughing) approach. It uses fewer fertilisers, retains stubble (lower part of stems) and grows cover crops.
103
What are the benefits/costs of resilient agricultural systems?
Benefits
* Increased yields and incomes for farmers
* Improved soil structure
* Higher-tech, drought-tolerant species help resistance to climate change and increase in diseases
* Low-tech measures and better practices generate healthier soils and may help carbon dioxide sequestration and water storage: selective irrigation, mulching, cover crops, crop rotation, reduced ploughing, agroforestry.
* More 'indoor' intensive farming
Costs
* More expensive technology, seeds and breeds unavailable to poor subsistence farmers without aid
* High energy costs from indoor and intensive farming
* Genetic modification is still debated, but frequently used to crease resistant strains, e.g. rice and soya
* Growing food insecurity in many places adds pressure to find 'quick fixes'
104
Explain land use planning (adaptation)
* Land use planning is a technique that allow the planning and management of land types to determine which areas of land should be chosen for which uses of land
105
What are the benefits/costs of land use planning?
Benefits
* Low cost approach
* permits the development of societies (through managing urban land use), whilst also maintaining the environment and its natural resources.
Costs
* Abandoning high-risk areas and land-use resettling is often unfeasible, as in megacities such as Dhaka, Bangladesh or Tokyo-Yokohama
* Needs strong governance, enforcement and compensation
106
Explain flood risk management (adaptation)
* Land use zoning is used for flood management, where development on floodplains is limited to low impact things like playing fields and parks
Hard engineering used: localised flood defences, river dredging
107
What are the benefits/costs of flood risk management?
Benefits
* Simple changes can reduce flood risk, e.g. permeable tarmac
* Reduced deforestation and more afforestation upstream to absorb water and reduce downstream flood risk
* If floodplains are made into parks/playing fields etc infiltration occurs naturally and surface runoff is reduced, leading to decreased risk of wider flooding
Costs
* Constant maintenance is needed in hard management, e.g. dredging; lapses of management can increase risk
* Expensive
108
Explain solar radiation management (adaptation)
This is a form of climate engineering, which aims to reflect solar rays and so reduce global warming. Examples include pumping sulphur aerosols into the upper atmosphere, cloud brightening, and space-based reflectors.
109
What are the benefits/costs of solar radiation management?
Benefits
* Techniques could be deployed relatively quickly and they offset some of the effects of greenhouse gases.
Costs
* Uncertainty about how effective they could be, together with ethical, social and political issues surrounding their use-plus they are potentially expensive .
110
Explain carbon taxation (mitigation)
A carbon tax is a fee or cost paid by users of fossil fuels, which is directly linked to the level of CO2 emissions that the fuel produces. The UK's carbon price floor (CPF) is a tax on fossil fuels used to generate electricity, and came into effect in 2013.
111
What are the benefits/costs of carbon taxation?
Benefits
* Idea is that it sends a message to change to a form of energy which produces fewer emissions.
Costs
* Won't guarantee a reduction in the level of CO2 emissions
112
Explain energy efficiency (mitigation)
The Green Deal scheme encouraged energy-saving improvements to homes, such as efficient boilers and lighting, and improved insulation. It was scrapped in 2015. Energy suppliers must comply with the Energy Company Obligation scheme to deliver energy-efficient measures to households.
113
What are the benefits/costs of energy efficiency?
Benefits
* Lower green house gas emissions and other pollutants as well as decreased water usage
Costs
* Increased cost
114
Explain afforestation and reforestation (mitigation)
Afforestation - planting trees on land not previously forested.
Reforestation - planting trees on land where deforestation has occurred.
Tree planting in the UK is increasing, helping carbon sequestration. It involves the Forestry Commission, charities such as the National Trust and the Woodland Trust, landowners and local authorities.
The Big Tree Plant campaign encourages communities to plant 1 million new trees, mostly in urban areas.
115
What are the benefits/costs of afforestation/reforestation?
Benefits
* The programme means that 2/3 of South Korea is now forested.
* Restoration of degraded environments
* Prevention of soil erosion
* Provision of forest sinks and stores of CO2
Costs
* Illegal logging still occurs
* Loss of land for agriculture and urbanisation
116
Explain renewable switching (mitigation)
Switching energy sources from fossil fuels to the use of renewables. The relationship between the big energy producers and the government dictates the amount of switching from fossil fuels to renewables and nuclear power. Renewables provide intermittent electricity, while fossil fuels provide the continuous power essential for our current infrastructure.
117
What are the benefits/costs of renewable switching?
Benefits
* Oil use in Sweden has reduced from 75% in 1970 to 20% today
* Lowers carbon emissions
* Provides jobs in the manufacturing and instalment process (e.g. Hinkley Point created 25,000 jobs)
Costs
* Can pose other risks e.g. Nuclear power has the potential to release radiation (Fukushima nuclear power plant in Japan 2011 earthquake)
* Large set up costs
* Not viable without a high strike price (e.g. Solar energy)
* Can also have CO2 emissions (e.g. Some biofuels such as rapeseed and palm oil) have needs for fertilisers and irrigation
118
Explain carbon capture and storage (mitigation)
Uses technology to capture CO2 emissions from coal-fired power stations. The gas is stored, compressed and transport by pipeline to an injection well where it's injected into geological reservoirs deep underground.
119
What are the benefits/costs of carbon capture and storage?
Benefits
* Reduces greenhouse gas emissions by 1 million tonnes a year
* Could cut global CO2 emissions by up to 19%
Costs
* Not currently financially viable
* Adds an additional expense to energy production
Geography - physical
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