Carbon Cycle Flashcards
(81 cards)
1
Q
What is a store/reservoir?
A
place where carbon is held
2
Q
What are carbon fluxes?
A
flows of movement between carbon stores which can operate at local or global scales
3
Q
What is used to measure carbon?
A
petagrams (pg) / gigatonnes (gt)
- one petagram equal to 1 trillion kg
4
Q
What are the two types of carbon?
A
- geological carbon (formed when sedimentary rocks are created e.g. Himalayas is one of the largest carbon stores, started off as oceanic sediment, now weathering and returning to oceans)
- biological carbon - derived from dead organisms eg coal and shale
5
Q
Why is carbon important?
A
vital in joining elements to form compounds necessary for life e.g. starches, these forms of carbon account for half of the total dry mass of living things
6
Q
What is a carbon source and sink?
A
sources add carbon to the atmosphere e.g. fossil fuels, respiration
sinks remove carbon from the atmosphere e.g. photosynthesis, ocean uptake
(- reservoirs can be either of these)
7
Q
What happens if carbon sources equal sinks?
A
the carbon cycle is in equilibrium (in a negative feedback system)
8
Q
What is the difference between positive and negative feedback systems?
A
- negative feedback systems maintain a stable state by preventing the system moving beyond thresholds - any change is cancelled out so equilibrium is maintained
- positive feedback systems occur when sources and sinks are unequal to each other so are not in equilibrium - a change in one component causes changes in others
9
Q
What are the four key processes involved in the carbon cycle?
A
- photosynthesis
- respiration
- decomposition
- combustion
10
Q
What happens in photosynthesis?
A
- process by which plants absorb light energy using chlorophyll in the leaves
- absorbed energy converts CO2 in the air and water in the soil into glucose
- some glucose used in respiration (rest used as starch)
11
Q
What happens in respiration?
A
- chemical process where glucose is converted into energy used for growth and repair, movement and maintenance of body temperature
- CO2 is returned to atmosphere, mostly through exhaled air
12
Q
What happens in decomposition?
A
- organisms die and are consumed by decomposers e.g. bacteria, fungi and earthworms
- during this time, carbon is returned from their bodies to the atmosphere as CO2, some material passes into the soil where it may be stored for hundreds of years
13
Q
What happens in combustion?
A
- organic material containing carbon is burned in the presence of oxygen
- it is converted into energy, CO2 and water
- this CO2 is released into the atmosphere, returning carbon that may have been stored for millions of years
14
Q
What does sequestered mean in terms of carbon?
A
naturally stored in physical or biological processes
15
Q
Where are the locations of the world’s largest carbon stores?
A
- central Africa
- Philippines
16
Q
What are the long term carbon stores?
A
- crustal/terrestrial/geological carbon store - 100,000,000 pg stored as sedimentary rocks with very slow cycling over thousands of years
- oceanic carbon store - 38,000 pg of dissolved carbon stored at great depths
- atmospheric carbon store - 560 pg stored as greenhouse gases with lifetime up to 100 years
17
Q
What are the short term carbon stores?
A
- terrestrial soil store - 1,500 pg from plant materials, microorganisms break down organic matter into CO2 - takes days in hot climate, decades in colder
- oceanic surface store - 1,000 pg through CO2 dissolving into the water and plankton
- terrestrial ecosystems - store 560 pg of carbon organically, especially in trees, rapid exchange with atmosphere of seconds/minutes
18
Q
What are the processes in the geological carbon cycle?
A
- physical/chemical/biological weathering of rocks in situ
- decomposition of plant/animal particles
- transportation - rivers carry particles to the ocean
- sedimentation occurs as particles accumulate
- metamorphosis occurs as the layering and burial of sediment causes pressure to build such that the deeper sediments are changed into rocks
19
Q
How much carbon moves through the cycle (between rocks, soil, ocean and atmosphere) annually?
A
10-100 million metric tonnes
20
Q
How is crude oil formed?
A
- remains of plants may form peat and then coal which may take 10-100s million years to form
- high temperature and pressure creates anthracite which has a high energy potential
- anaerobic reactions convert 90% of this organic carbon to liquid which then moves into other rock layers where it becomes trapped
- crude oil is 85% carbon
21
Q
How is limestone formed?
A
- skeletons of marine creatures which had extracted carbon from seawater and phytoplankton
- their remains accumulate on the sea floor and cement and compact into calcium carbonate in limestone
22
Q
How much CO2 does volcanic activity release annually?
A
300 million tonnes of CO2
23
Q
How do volcanoes release carbon?
A
- volcanoes degas through the main vent of the volcano/hot spot
- degassing also occurs at divergent plate margins
- at convergent margins carbon is recycled as carbonate rocks are dragged into the upper mantle
24
Q
Do you know the rock cycle?
A
- igneous rock
- uplift to surface
- weathering
- transport and deposition
- sedimentation
- compaction
- sedimentary rock
- burial, high temp and pressure
- metamorphic
- melting to magma
- crystallisation of magma
- igneous rock
25
What are the biological processes separating carbon?
- biological pump
- carbonate pump
- physical pump
26
How does the biological pump separate carbon?
- phytoplankton float on the surface of the ocean to access sunlight and photosynthesise
- carbon then passed up the food chain by consumers, which release CO2 back to atmosphere - phytoplankton act as the basis of the marine food web, making up 1/2 of the planet's biomass
- phytoplankton sequester 2 billion metric tonnes of CO2 to deep ocean anually
27
How does the carbonate pump separate carbon?
- marine organisms use calcium carbonate to make outer skeletons, when they die, shells will dissolve on way to sea bed and carbon becomes part of the ocean, flowing around the world in currents
- shell that doesnt dissolve builds up on sea floor, forming limestone sediment e.g. those in White Cliffs of Dover
28
How does the physical pump separate carbon?
- oceanic circulation of water whereby CO2 is mixed much slower than it is in the atmosphere, causing large spatial differences in concentration
- colder water absorbs more CO2 so deep ocean has 10% higher concentration than surface/polar regions, warmer water releases CO2 into atmosphere
- large ocean currents e.g. North Atlantic Drift move water from tropics to poles - where water cools and absorbs more CO2
29
What is thermohaline circulation?
- part of global ocean nutrient/CO2 cycles - warm surface water is depleted of nutrients and CO2 but are enriched again as they travel through deeper layers
1. main current begins in cold polar regions, water increases in density and sinks
2. current is recharged as it passes Antarctica by extra cold, salty, dense water
3. main current divides: north and west
4. the two branches become warm and rise then loop westward
5. now-warm waters continue circulating the globe, join up and eventually cool again at North Atlantic
- this circulation helps shift carbon in the carbonate pump cycle from upper to deeper waters
30
What is phytoplankton?
- basis of marine food web
- provide 1/2 of the earths oxygen
- absorb CO2 from surface ocean and float on surface to access sunlight - this carbon then eaten and passed down the food chain
31
How does amount of phytoplankton vary?
- thrive along coastlines
- found along equator in pacific/atlantic oceans
- thrive in high latitude areas
- this is because they favour cold oceans rich in nutrients from deep water upwelling, as well as sunlight
32
How does terrestrial sequestration take place?
- primary producers take in carbon via photosynthesis, release CO2 back into atmosphere through respiration
- consumer animals eat the plants and absorb carbon, becoming part of animal fats/proteins
- animal dies and microorganisms feed on waste material, incl carbon uptake
- remaining animal body decays into soils - process of decomposition happens fastest in tropical climates
- terrestrial sequestration is the fastest part of the carbon cycle, taking just seconds (most productive biomes are tropical forests, savannah, grasslands)
33
How does soil sequester carbon and what are the factors impacting it?
- store 20-30% of global carbon
- sequester 3x that of the terrestrial store
- sequestration is affected by: climate (arid soils store 30 tonnes per hectare, cold soils store 800 tonnes), soil type (clay rich soils protect carbon from decomposition so have higher carbon content than sandy), management/use of soils (soils globally lost 40-90 billion tonnes of carbon since 1850 from cultivation/disturbance
34
What percentage of short wave radiation is absorbed (particularly by oceans)?
69% - that which is emitted is often reflected back to earth by GHGs
35
How long does carbon remain in the atmosphere?
2000 years
36
What are the causes of GHGs?
- industry (from combustion of fossil fuels)
- agriculture (methane from livestock, deforestation for farmland, loss of soil carbon from ploughing)
- electricity generation (increasing demand from increasing population)
- transport
- cement production (concrete is most consumed product in the world after water, chemical processes involved in production release CO2, 6% of global emissions)
- wetland/peatland loss (store 550Gt of carbon, twice as much as world forest biomass combined, but only cover 3% of surface)
37
What are the implications of climate change?
- climate: 2015 hottest year on record, average world temp 1 degree hotter than pre-industrial times - causes melting of permafrost etc (however increased agriculture/tourism)
- ecosystems: habitat changes will cause extinction of 10% of land species, temp and acidification of water (carbonic acid) will threaten corals e.g. heat stress has encompassed 51% of all coral reefs, habitat will shift poleward e.g. butterflies have shifted northwards by 6km in a decade
- hydrological cycle: increased flooding, extreme precipitation events, permafrost thawing (however more land for farming and access to fossil fuels), rivers will dry in some areas, disappearance of glaciers etc
38
How does demand for energy vary?
- 1/2 population live in cities - consume 75% of energy and produce 80% of GHGs
- e.g. London provides 1.7 million tonnes of carbon /year
- France energy consumption is 1/10 that of USA - due to USA's bigger population and climate variations mean more energy required for air con, heating etc
- fossil fuels provide 50% of French energy, 80% of US energy
39
Why does energy consumption vary?
- physical availability (is it available in country? imported energy requires transport which adds to overall cost for consumers, rising costs are likely to reduce consumption, is extraction expensive?)
- technology (can help exploitation of energy difficult to access, increases consumption but modern technology does use a lot of energy)
- climate (e.g. high consumption in USA from heating/air conditioning)
- cost (incl cost of exploitation, processing and delivery, with low costs boosting consumption)
- economic development (implicates perception of energy costs)
- environmental priorities (green energy policies are expensive, concern for environment may reduce consumption)
40
What is energy mix?
the proportion of each primary energy resource it used per year - global energy is dominated by 80% fossil fuels
- primary energy is that which has not been converted into other forms, secondary is that which has been converted e.g. into electricity
41
What are the factors affecting energy mix?
- financial costs
- energy needs of the country (based on economic development, lifestyle, climate)
- cultural/historical legacies, geopolitical links
- accessibility to primary energy resources within the country
- accessibility to primary energy resources from outside the country
- regional/national policies affecting energy production/consumption e.g. climate change
- changing consumption patterns linked to population and economic growth
42
What are the factors affecting energy consumption/security in the UK vs Norway?
- physical availability
- cost
- technology
- political considerations
- environmental priorities
- economic development
43
How does physical availability affect energy consumption/security in the UK compared to Norway?
UK depended on domestic coal and was global leader in nuclear technology until 1970s, until discovery of oil/gas in north sea - Norway's steep valleys/rainfall make HEP popular, fossil fuels from its waters are exported
44
How does cost affect energy consumption/security in the UK compared to Norway?
north sea oil is 'secure' alternative to middle east but expensive to extract so may be less viable if global prices fall - Norsk Hydro runs 600 HEP sites in Norway, supplying 97.5% of its renewable electricity, low cost following initial capital investment however transferring energy to other areas is expensive
45
How does technology affect energy consumption/security in the UK compared to Norway?
UK's current technology/environmental policy make extraction of its 150 years of coal reserves unrealistic but 80% of energy still from fossil fuels, tech exists for 'clean coal' but coal has lost political support - deepwater drilling has enabled oil/gas extraction for both countries
46
How do political considerations affect energy consumption/security in the UK compared to Norway?
UK reliance on imported energy affects security, public concern over fracking/nuclear sites, energy supply industry privatised in 1980s to over-seas countries - HEP used in Norway since 1907 under nationalised system, profits to sovereign wealth fund to prepare for future without fossil fuels
47
How do environmental priorities affect energy consumption/security in the UK compared to Norway?
both committed to 40% reduction in domestic emissions by 2030, however UK abandons 'Green Deal' schemes in 2015, Norway launched 'policy for change' 2016 with target for carbon neutral by 2050
48
How does economic development affect energy consumption/security in the UK compared to Norway?
GDP/capita: $41,200 UK, $61,500 Norway
CO2 emissions per capita 2014: UK 6.5 tonnes, Norway 9.27 tonnes
2015 annual household energy costs: £1300 UK, £2400 Norway
49
What is an energy pathway?
- the flow of energy between the producer to consumer and how it reaches the consumer
50
What are the 3 objectives of energy players, as suggested by the World Energy Council?
1. energy security
2. energy equity (accessible for every country)
3. environmental stability
51
What are the 5 major energy players?
- governments (influence sourcing for geopolitical reasons, to meet international obligations incl environmental policies, and to regulate private companies)
- energy companies (convert primary-secondary and distribute energy, influence in consumer prices/tariffs)
- OPEC (12 members owning 2/3 of oil reserves, control price and quantity of oil/gas entering global market)
- TNCs (50% of top 20 oil companies are state owned, have range of operations in all stages of pathway e.g. Gazprom
- consumers (create demand in terms of transport, industry, domestics. purchasing choices often based on price issues, passive players in fixing prices)
52
What are some examples of energy companies?
- Gazprom: state-owned gas producer in Russia, involved in eevry step of energy pathway e.g. extraction from Siberia, control pipelinesm own 20% of world gas reserves, exports 80% to Europe, Nord Stream Pipeline 1200km along Baltic Sea to avoid other countries
- British Petroleum (BP): UK/US based, privatised in 1980, 6th largest non-state owned company, provides 50% of UK oil production, $6.7 billion in profit 2017, operate in 78 countries
53
In what ways is fossil fuel distribution uneven across the world?
- coil/oil/gas only found under certain geological conditions - disparity between production and areas of high demand creates a mis-match
54
What are the threats to energy pathways?
- natural obstacles e.g. energy must travel large distances, difficult terrain
- weather/natural hazards e.g. damage to pipelines in storms in UK 2013 meant gas reserves fell to 6 hours worth
- militant action e.g. bombed pipelines, seized ships - e.g. Iran wants to export its gas via pipelines in Syria so defended Syrian government from those trying to replace Assad regime
- political tensions/disagreements - lead to choke points being blocked e.g. 3/4 Russia's pipelines cross Ukraine to get to Europe but conflict with Ukraine threatens this e.g. Ukraine could increase prices for allowing gas to enter it, or could stop flow - oil 'choke point' of the Strait of Hormuz where 20% of world oil passes through
55
What are unconventional fossil fuels and why are they used?
unconventional fossil fuels - fossil fuels produced using different methods incl:
- tar sands, shale gas (fracking) and deep water oil
- used when peak production of oil becomes a threat, cost of fossil fuels increases, fossil fuels are running out
56
What is the Tar Sands case study of an unconventional fossil fuel?
- mixture of clay, sand, water and bitumen
- bitumen is too viscous to be pumped out so must be taken from open pit or strip mined, then separated from sands using hot water and lighter hydrocarbons
- largest reserves in Alberta:
- benefits: economically viable when oil prices are high, provide $4 trillion to economy (2015-35), 151,000 direct jobs created, produces 40% of Canada's oil output, production to reach 4 million barrels a day by 2030
- implications: uses high energy resulting in 3x higher contribution to global warming than conventional oil, uses 4 barrels of water for 1 barrel of oil, proposed sites infringe on indigenous rights over hunting grounds
57
What is the Deep Water Drilling case study of an unconventional fossil fuel?
- offshore drilling involves wellbore being drilled below the seabed to underground oil reserve, gravity/pressure in the reserve forces oil into wellbore, then water pumped into reserve to increase formation pressure
- Brazil: discovery of oil fields put it in centre of global energy
- benefits: only 13% of electricity is generated by fossil fuels so this oil production will produce more variety (improves security), $258 billion investment to Rio with 500,000 jobs by 2020
- implications: dangerous due to presence of flammable rock, rigs hard to maintain as hard to reach over water, $221 billion spent on ship fleet, oil spills pollute water
58
What is the Shale Gas case study of an unconventional fossil fuel?
...
59
How many years of coal is left in the UK?
150 years
60
What percentage of UK energy is imported?
60%
61
When does the UK plan to close all its traditional coal-fired power stations?
2025
62
What does the IPCC say about climate change?
says to reduce climate change, renewable cshares should at least treble by 2050
63
How much did solar energy use increase by in 2014?
38.2%
64
What are the strengths of using solar power?
- safe, clean, non-polluting once installed
- renewable (wont compromise future gen)
- can be used in poorer countries due to low operating costs
- flexible/modular so can be used on roofs of buildings
65
What are the limitations of using solar power?
- not enough research into storage methods - energy often must be consumed where it is produced
- electricity produced is more expensive
- not effective in cloudy conditions or polar regions
66
Which country is a world leader in solar power?
- Kenya
- has 30,000+ solar panels producing 12-30 watts each
- not reliant on fossil fuels so not vulnerable to price fluctuations, dont have to spend a lot of money connecting rural communities to the grid, can instead set up solar systems independently
67
What are the casestudies for nuclear power?
- 27% of Japan electrcity pre-2011 but Fukushima prompted closure of all
- Hinkley Point £18 billion project in Somerset to provide 60 years of energy and 25,000 jobs for 10 years
68
What is the casestudy for wind power?
- Hornsea Project aims to install turbines 120km off Yorkshire coast, providing power for 1 million homes, 2000 jobs in construction
69
What is the casestudy for biofuels?
- Brazil was first to produce biofuel from sugar cane in 1970s - bio-ethanol cheaper as vehicle fuel, emit 80% less CO2
- Brazil aims to double production by 2024 however deforestation increases
70
What are the 3 radical technologies that have been developed to combat climate change/offer alternatives to fossil fuels?
- carbon capture and storage: systems collecting CO2 from points e.g. power plants, then transports gas and injects it into geological structures - could cut emissions by 19% however expensive and CO2 can leak
- hydrogen fuel cells: alternative to oil, used in hydrogen engine providing no pollution, only waste product is water e.g. Toyota developed car in 2015, NASA uses liquid hydrogen for space shuttles since 70s
- electric vehicles: 10,000 charging stations in UK, travel 62-340 miles, zero emissions, no noise pollution, but expensive
71
What percentage of temperate forests in UK and USA were deforested in 19th century?
90%
72
How much land is deforested annually?
13 million hectares
73
How much of the earths surface is covered by forest?
30% but only 15% are natural
74
What are the ways human activities impact the carbon/hydrological cycle?
- afforestation (e.g. China's Three-North Shelterbelt Project, 4500km green wall of trees to reduce desertification, monocultures have negative impact on biodiversity, habitat change, often store less carbon, may lead to less infiltration)
- grassland conversion (e.g. US Renewable Fuel Standard Policy encouraged farmers to grow biofuels, corn, soya, rapeseed etc, 5.5 million hectares of natural grassland ploughed, less carbon, infiltration rates change)
- deforestation (90% of Madagascar deforested from expanding population, demand for hardwood, gov doesnt provide funding for people, causes drought, more flooding etc)
- climate change increases drought (from shifting climate belts, increase in dry regions, e.g. in Amazon: absorbs 10% of fossil fuel emissions, but drought caused canopy trees to decline 35 inches, 2005 drought lost 0.27 petagrams of carbon a year, 2010 drought caused dead trees spanning 1.2 million miles and 8bn tonnes of carbon released)
- ocean acidification...
75
How much human-produced CO2 does the ocean absorb and what does this mean for the ocean?
30% - has caused acidity of oceans as carbonic acid dissolves and lower pH
76
What have been the effects of ocean acidification?
- ocean now 30% more acidic than in 1750
- corals become unable to absorb the calcium carbonate needed to maintain skeletons, therefore reefs begin to dissolve, coral releases algae (originally absorbed for food), turning it white - also can only survive a narrow temp of 23-29 degrees
77
How does forest loss affect human wellbeing?
- 1.6 billion depend on forest - 13.2 million formal jobs, 41 million informal jobs, educational value, source of 80% global biodiversity and provides 1.1% of global economy income
78
How much palm oil is produced per year?
66 million tonnes
79
What does Kuznets Curve show?
shows how levels of environmental degradation change with GDP per capita - industrial economies hit 'turning point' in their environmental degradation and post-industrial economies reduce exploitation and move towards protection
80
What is Indonesia's forestry casestudy?
- largest producer of palm oil
- GHG emissions took over USA's in 2015
- 700 land conflicts linked to palm oil in 2016 as indigenous people often driven out of areas they had inhabited for generations
- president has declared a 'forest moratorium' aimed at reducing deforestation
- $1 billion from UN and Norway in funding, stopped new lands getting forest clearance permits, extended in 2015 to reduce CO2 by 26% by 2020
- illegal logging remains an issue
81
What have been the successes of managing climate issues?
- rate of global deforestation has slowed by 50%
- forest carbon emissions decreased by 25% according to UN
- 13% of forests now classed as 'conserved'
- Brazil and USA have largest National Parks
- 13% of UK is now forested with increased number of indigenous trees planted
