The Carbon Cycle

  • Created by: holly_u
  • Created on: 21-04-18 14:42

Biogeochemical Carbon Cycle

carbon cycle= a cycle in which carbon moves from one sphere to another . It's a closed-system with sub-systems with inputs, throughputs and outputs.

flux= measurements of the rate of flow of material between stores.

If sources equal sinks, dynamic equilibrium is obtained.
positive feedback- (amplifying) a change in one component causes other changes
negative feedback- (stabilising) maintaining equilibrium

Carbon stores:
Terrestrial geological- sedimentary rocks, 100,000,000 PgC (fluxes per year)
Oceanic (deep)- dissolved inorganic carbon

Oceanic (surface)- rapid physical processes e.g CO2 dissolving, biological processes (plankton). 1000 PgC
Atmospheric (CO2)- greenhouse gases. 560 PgC
Terrestrial ecosystems- plant photosynthesis. 560 PgC

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Size of Stores

Size order:
Lithosphere (fossil fuels, sedimentary rock, crust) Crust alone holds 100,000,000 tonnes of carbon

Hydrosphere (dissolved CO2) Oceans holds 38,000 tonnes

Cryosphere (frozen water)

Atmosphere (CO2)

Biosphere (living/ dead organisms) 

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Geological Cycle

Geological Cycle:
- Slow part of cycle. Millions of years
- organic matter buried and transferred to coal, oil or gas
- released through weathering and volcanic outgassing

Sedimentary Carbonate Rocks e.g Limestone
1) oceanic sediments compressed and folded e.g Himalaya Mountains, this is actively eroded by weather etc

Biologically made rocks
1) organic carbon from organisms embedded in layers of mud and heat and pressure compresses in oceans

Fossil Fuels
remains of organic material, sink to bottom and decay 
Oil and gas = in pockets of rock
Coal = remains of trees and plants. Peat is stage before coal. Anthracite- hardest, most carbon
Bituminous- slightly less hard & carbon
Soft coals- 25-30% less carbon, global source of energy, but more CO2

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Geological Processes

Mechanical- break up of rocks. freeze-thaw creates small tranportable particles
Chemical- Carbonic acid in rain breaking down rocks
Biological- Rock boring animals e.g clams burrow and plants break rocks up

Particles transported by rivers (carbon cycle) and deposited eventually creating more rock.

Seafloor subduction melts rock and CO2 released

Volcanic Outgassing
Volcanic eruptions allow fluxes into atmosphere at:
- active tectonic boundaries e.g subduction zones, 
- inactive areas e.g Yellowstone National Park
- direct emissions from crust.

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Biological Processes

Ocean sequestration
Sequestration- natural stores of carbon 

1) BIOLOGICAL PUMP -moves carbon through biological processes
driven by marine organisms.
- Phytoplankton- organisms that have chlorophyll meaning they photosynthesise (intaking carbon). Foundation of the food web so transferring carbon. Small amounts reach ocean floor.

2) CARBONATE PUMP- moves carbon through carbon sedimentation
- CO2  dissolves in water producing biocarbonate ions. They combine with calcium and produce calcium carbonate allowing organisms e.g crabs to build shells.
Once dead they sink to bottom of ocean & metamorphisis turns to limestone

3) PHYSICAL PUMP- moves carbon through currents in ocean
-Thermohaline Circulation, when bands of water travel north when warm, once seawater cools it intakes more CO2 making denser to it sinks down to south. 

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Terrestrial Processes

Terrestrial Sequestration
natural stores of carbon on the earths land

SHORTEST TIME (seconds, minutes, years)
1) Photosynthesis- plants absorb carbon from the atmosphere through chlorophyll
2) Respiration- Plants release small amounts
3) Animals eat plants therefore intaking carbon and micro-organisms e.g beetles feed on animal waste
3) Litterfall- dead plant material is decomposed, particularly in tropical climates

Varying fluxes:
Diurnally- during day more photosynthesis due to sunlight, at night only respiration
Seasonally- winter more photosynthesis as more decaying material, spring less.

Store 20-30% of global carbon. Organic source e.g decomposition and photosynthesis from losses from plant. Things affecting capacity: depth soil (e.g permafrost 30cm), climate (higher temperatures more decomposition), soil-type (clay-rich higher content than sandy) & use of soils (cultivation disturbes levels)

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Balanced Cycle

Positive Feedback- affecting dynamic equilibrium e.g burning fossil fuels
Negative Feedback- stabilising & slowing down global warming e.g volcanic eruption

Greenhouse Effect:
Natural process where sunlight warms surface of earth (50% absorbed), rays radiate outwards and trapped in O-zone layer retaining heat. Solar radiation highest along equator so more precipitation.

Atmosphere and Soils
Photosynthetic organisms keeps cycle balanced, so keeping temperature constant
Soil health depends on carbon levels. It gives soil water holding capacity, structure and fertility. Most carbon in surface soil, so soil erosion big threat. 

Enhanced Greenhouse Effect:
Humans burn fossil fuels, cattle farm, deforestation, jet aircrafts and pesticides increasing CO2 and methane. Overall warmer earth, so more evaporation and precipitation, so changing weather. Rising sea level, drought, floods. 

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Impacts of Enhanced Greenhouse Effect

Impacts on ecosystems:
- lower oxygen levels for marine organisms, more ocean acidification and higher temperatures affecting food chain
- coral reefs will die - coral bleaching
- animals extinct e.g polar bears/
- plants less adaptation than animals. so affected by pests & diseases.

Impacts on hydrological cycle:
- permafrost will thaw increasing sea levels - salt water encrochment
- fresh water glaciers will melt
- increased evaporation, more moisture in atmosphere - increased precipitation
- ENSO events more intense

Impacts on climate:
- drier area e.g the Sahel, South Africa
- tropical zones so stronger storm activity
- arctic regions temperatures increase

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Energy Security

Energy security= uninterrupted availability of energy sources at an affordable price

- Usually evaluated at National level
- 4 aspects: availability, affordability, accessibility and reliability

Energy Consumption
measured per capita (total amount divided by population)
megawatt per hour - MWh/yr  
kg of oil per year- kgoe/yr

Measuring efficiency of consumption= energy intensity. measured by units of energy used per unit of GDP. Energy intensity increases with economic development

Energy Mix (comination of different energy sources to meet a countrys demand)

Renewable (wind power) or non-renewable (fossil fuels)
Domestic (in the country) or foreign (imported sources)
A high dependence on imported sources reduces security as blackmail, changing prices & supplies cut off e.g Russia to Ukraine

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UK Energy Mix

44% gas - non-renewable
22% nuclear - non - renewable
12% wind - renewable

Until 1970s coal main UK provider, until North Sea resevoir gas and oil found. Secure supply but expensive. Rely on foreign resources reduces security.

Future expected to increase renewable energy sources, coal to decrease. Fracking.

82% carbon (non-renewable energy)
10% renewable
8% nuclear

Small amount of imports- so more secure

Mountainous so Hydroelectric power major source & export oil and gas e.g to UK

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Energy Consumption

Access to depends on:

  • Physical availability- available within country or imported?
  • Technology- modern technology allowing less easily extractable resources to be removed.
  • Cost- cost of physical extraction, processing and transport to customer
  • Economic development- lower economic countries may percieve as more expensive. 
  • Climate- particularly hot/ cold climates have high consumption due to air conditioning/
    heating. Africa anomaly
  • Environmental priorities- if a government is concerned about environment more renewable sources used
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Energy Players

Energy pathway= route taken from source to consumption

TNCs (companies with HQs in HIC and manufacturing/ production in LIC)
- source the energy and extract it
- mostly under government control (state-owned)
- sell energy

OPEC (12 member countries, owning most oil)
- control oil prices
- sometimes hold back to increase prices, so affects energy security

Energy Companies (convert primary oil into electrcity)
- distribution of energy

Consumers (people who use the energy)
- most influential over amount of energy needed, passive influence on fixing prices

- influence the sourcing of energy. 

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Mismatch between Supply and Demand

Fossil fuel supplies:
COAL- biggest supplier China, also biggest user + USA

OIL- two main suppliers= OPEC and North America
Mismatch in Europe as large consumer and little producer.
No subsitute to oil

GAS- biggest users are biggest producers (utilise resources). USA and Russia

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Energy Pathways

Types of energy pathway: pipelines, shipping routes, electricity power lines, 

OIL- Middle East largest producer so flows to Asia, Europe, USA. 
Russia to Europe
Ship and pipelines

GAS- less globally required, normally through pipelines or converted to liquid and moved by ships

COAL- Previously would be much higher. Still significant trade.

Prone to disruption due to:
- weather/ hazards - UK 2013 storm surge, damage to pathway e.g pipeline, supply runs out, piracy e.g off the Somali coast & conflict - protests/ war

conflict between russia and ukraine over Crimea (oil & gas rich area). Putin wanted, so sent rebel troops but Ukraine fought for control. In 2014 Gazprom turned off gas supplies. Effects for Europe including UK, not energy secure. 

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Unconventional Fossil Fuels

Tar Sands- mixture of clay, tar & sand. It's mined, injected with steam to make more viscous so it can be pumped. 
e.g Canadian Tar Sands. biggest producer 
+  40% of Canada's exports& improves energy security. provides jobs
- But high energy required so expensive, habitat deconustruction, water pollution, carbon levels rise.

Players: government promote tar sands, environmental groups e.g Greenpeace against

Oil Shale- oil- bearing rocks, oil is pumped directly. - uses energy, releasing co2

Shale gas- natural gas trapped in sedimentary rock. Using fracking to pump water in and force gas out.
e.g Utah, USA. 14 million barrels on 60 acres

Deepwater oil- oil and gas offshore at deep depths.Using ocean rigs  + reach places not previously accessible.  - which have toxic and flammable gases so problem if accident occurs. e.g off Brazilian coast, 200km offshore and drills 2,000m below surface

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Renewable Energy

Renewable energy= source that naturally restores itself without human influence
Recyclable energy= source that can be used over and over, often requires human influence

Hydroelectric power (power derived from falling/ running water)
e.g Three Gorges Dam China. Largest capacity power station
+ No co2 emissions and constant source
- high initial cost and displaces people to make space

Wind power (electrical energy harnessed from the wind)
e.g Hornsea Project 1- Yorkshire. 
+ Job opportunites for manufacturing and maintaining
- NIMBY problems (eye-sore) and not constant supply

Solar power (power obtained from the sun's rays)
e.g Chapel lane solar farm, Dorset. Summers day able to power 60,000 homes
+ No co2 emissions and low maintenance
- High initial costs and not constant - weather dependent

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Recyclable Energy & Alternative Sources

Renewable energy= source of energy that naturally replenishes itself without human influence
Recyclable energy= source that can be used over & over, often requires human influence

Nuclear Power (power generated by a nuclear reactor)
+ 'Green energy' 0 co2 emissions and high energy production
- Accidents cause harm e.g Fukishima power plant. 3 years later nuclear waste in oceans, terrorism threats using nuclear power & hard to dispose of nuclear waste - very toxic

Alternative sources:
Biofuels (power generated from biological sources e.g agriculture)
PRIMARY- fuelwood
SECONDARY- processing e.g biodiesel

e.g Rapeseed oil in EU. Cultivated historically since 1200 AD
Brazil, bioethanol. Using fermented sugar cane to produce alcohol-based fuel for energy
+ reduced carbon emissions (but still produces some e.g burning fuelwood)
- Deforestation - Brazil, so reducing photosynthesis and pesticides toxic substances which can contaminate water supplies and cause cancer 

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Radical Technologies

CARBON CAPTURE & STORAGE- trapping co2 before combustion, then stored underground
+ decreases carbon emissions globally
- expensive as complex processes, carbon might not stay underground- slowly released?

HYDROGEN FUEL CELLS- oxygen combined with hydrogen in fuel to create chemical reaction that powers electric cars
+ can be used for heating, electricity, electric vehicles, eliminates pollution, only by-product is water

ELECTRIC CARS- rechargeable batteries power the car
+ no emissions & reduce noise pollution
- expensive & batteries have to be replaces

SOLAR COOKERS/ LIGHTING- aluminium sheets collect solar energy 
+ cheap, good for LICs, reduces fires so less woof burned
- weather dependent, some LICs won't have enough sunlight

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Ecosystem Services

Many benefits humans gain from the properly functioning ecosystems

Regulating (earths systems, globally)
benefits from regulating an ecosystem e.g regulating air quality, natural hazards, erosion

Supporting (actual ecosystem, local)
keep ecosystems healthy by providing sevices e.g photosynthesis, soil formation

non-material benefits from ecosystems e.g tribes worshipping mountains

products obtained from ecosystems e.g food, fuelwood, water, remedies

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Affects on Land-Use Cover- Deforestation

permanent destruction of forests for cattle farming, fuelwood, urbanisation, building materials.
methods: burning trees by clear cutting (removal of all) or slash and burn allowing re-growth

Effects: temperate forests e.g UK and tropical forests e.g Brazil, destroyed creating barren land, loss of culture, loss of leisure and tourism.
On water cycle: reduces interception so soil and groundwater infiltration affected, soil erosion, more arid soils
On carbon cycle: reduction in carbon in soil and biomass, less photosynethis, more atmosphere

e.g Amazon Rainforest, Brazil
World bank gives money for mining, construction of dams and infrastructure so increasing deforestation.
Causing indigenous people to leave 

Players: human well-being can be improved by players e.g government having more sustainable approach

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Afforestation & Grassland Conversion

planting trees on land that never had forest/ without forest for long time period

+ beneficial for co2 sequestration
- controversial impacts. Commercial (non-indigenous) trees e.g palm oil plantations, use more water and are disease prone. 

Grassland Conversion to farming
Two types:
Tropical grassland/ savannah- scattered trees e.g Africa
Temperate grassland- no trees e.g 

- Grassland used to intensively for animals/ ploughed up, disrupts carbon and water cycle. 
- rapid population growth and ecosystem reduces carbon storage

e.g American Midwest. Prairies used to be flat, fertile lands used for bison hunting and ranching. Now used for food production

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Ocean Acidification

The decrease in pH of the Earths oceans caused by uptake of co2 from the atmosphere (dissolved)

Critical threshold= an abrupt change in an ecological state. Small environmental changes having a bigger effect. Positive/ negative feedback loops reinforce changes.

Ocean acificication increases chances of reaching critical threshold of permanent damage.

Increased by:
global warming, cyclones, pollution, quick speed

Shell-building organisms struggle due to reduced carbonate, so more fragile shells
Coral bleaching (algae living on die)  from increased temperatures- reduced tourism
Sea grass, acts as protection for fish, reduced, fish populations decline
Arctic oceans affected most because of low pH. Dark ocean absorbs more heat

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Climate Change

Climate change is occuring due to the Enhanced Greenhouse Effect caused by anthropegenic reasons. Humans are requiring more fossil fuels for every day life due to people becoming more affulent, therefore more emissions e.g carbon dioxide and methane are being released. With more carbon in the atmosphere global warming increases as heat is trapped, causing increasing temperatures.

Frequency of drought is increasing
more moisture evaporates from resevoirs e.g lakes
drier soils
less able to absorb water, so drought

Shifting climate belts
Cold climate zones will decrease in size
Temperate areas e.g UK, will experience hotter summers and cooler winters

AMAZON DROUGHT- severe drought 2014. It holds 17% of terrestrial vegetation. The drought stopped functioning as a carbon sink. Trees died, growth declines & forest fires, co2 atmophere

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Impacts of Forest Loss

Forests are vital for human well-being

Forest eco-system services:
Supporting function- nutrient cycling, soil formation, primary production, photosynthesis
Regulation earths systems- regulates climate & floods, water purification. Threats= deforestation, water related risks & air and water pollution.
Culture- education, recreational e.g Kielder Forest, spiritual. Threats= tourism
Provision of goods- fuelwood, fresh water, building materials. 

Forests being protected in HIC and expanded. Sustainable management e.g UK 

Kuznets Curve:
curve showing how exploitation turns to protection
Pre-industrial= rising incomes worsen environmental impacts
Industrial= high environmental degradation but reach a 'tipping point'. China 20th century
Post-industrial= rising incomes reduce environmental impacts e.g China today

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Impacts of Rising Temperatures

Global warming increases temperatures. Causing amount of water in atmopshere to increase (more evaporation)

Impacts on precipitation:
warm air, more water vapour in atmosphere so wet get wetter and dry get dryer. Wet areas increase by 20%

Impacts on river regimes:
warm water flowing into the oceans including Arctic
Thermohaline circulation effected as warm freshwater disrupts sinking of cold

Impacts on water stores:
Cryosphere- melting. ALBEDO EFFECT. dark ocean absorbs more heat e.g Antrarctic ice sheets melting
PERMAFROST (layer of rock/soil frozen all year round) will melt, affecting infrastructure above and releasing methane.

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Ocean Health

Threats to Ocean Health:
Acidification- uptake of carbon from atmosphere causing decrease in pH of oceans
Bleaching- coral turning white due to organisms living off being ejected
Rising Sea Levels- Global warming causing rising sea levels due to albedo effect
Loss of sea ice- rising temperatures melting glaciers, ice sheets etc.. 

Effects on humans:

  • all countries, even landlocked e.g Chad, rely on fish. Supports 500 million people
  • necessity for poorer countries as cheap protein and seafood for income
  • tourism based around coral reefs and marine life affected
  • only large nations with fishing fleets will be able to follow fish
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Future of global warming is uncertain, as several causes human and natural.
Scientists use technology to measure co2 levels weekly & use aircrafts to measure higher.

Changes to terrestrial (land) sinks:
- permafrost thawing
- more forests as is thaws and warms, storing more co2
- tropical rainforests reduced carbon capacity as at peak currently

Changes to oceanic sinks:
- warming oceans so less uptake of co2
- slowing of biological pump- dissolving of carbon from surface to ocean floor

Human factors:
- rising population so more GHG used
- more globalisation and movements of goods requires more resources
- governments search for more alternative fuels e.g Fracking & Tar sands - USA

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Feedback Mechanisms

Feedback mechanisms:
Negative feedback- maintaining and stabilising carbon levels e.g volcaninc eruption
Positive feedback- one change causing further change, affecting dynamic equilibrium e.g ocean solubility, reducing levels of co2 in atmosphere

e.g Carbon release from peatlands and permafrost
Peatland= wet ecosystem with layers of plant material forming peat soil.When drained/ burned release lots of co2.  Land-use change releases this.
Permafrost= layer of frozen rock/soil all year round. Melting of permafrost releases methane and co2

Tipping points (a critical threshold- changes are unpredictable):
Forest die back= peripheral parts of plants/trees die to due drought, reach a point when change is irreversible

Changes to thermohaline circulation
release of warmer, freshwater affects ability of oceans to allow carbon to sink due to cold temperatures, reaches a critical point when system no longer works

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Climate-change adaptation= actions taken to adjust to changing climatic conditions. Can be hard strategies or soft strategies

Soft involves legislation. Laws enforced

Hard- requires technology

RESILIENT AGRICULUTRAL SYSTEMS, Northern China used crops which can withstand higher temperatures. 
+ resist climate change, decrease diseases, helps water storage, co2 sequestration increased
- subsistence farmers can't afford, genetic modification debated

FLOOD RISK MANAGEMENT, Australia adapting to flood risk by building flood resistant houses (raised floors) & people re-located
+ reduces effects of floods economically & socially
- constant maintenance, debate over funding and re-locating people cause conflict due to attachment

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Mitigation= reduction or prevention of Greenhouse gas emissions through new technologies and low carbon energies, or changing attitudes and behaviour.

fee/ cost paid by consumers of fossil fuels. Price linked to amount of co2 released.
UK, Carbon Price Floor (CPF) in 2013
+ makes people more aware of energy consumption
- causes conflict. Unpopular with industry and consumers

tree planting to counterbalance deforestation. UK 'The Big Tree Plant' Encourages communities to plant 1 million trees in urban areas
+ reduces flood impacts, more photosynthesis so less co2 in atmosphere
- affects biodiversity due to foreign species 

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Global Scale Agreements

International efforts to reduce GHG emisisions:

    aims of long and short term climate change mitigation. Reduce GHGs by 5% by 2012.
    + step forward for global mitigation, exceeded the 5% goal
    - China and USA not bound by agreement (top emitters), reductions may have been due to other reasons
    aims to keep global temperatures below 2 degrees for all the worlds nations.
    review each countrys contribution every 5 years
    HIC must help LICs to adapt

Hard to achieve global agreements due to differing economic levels. 
LICs contribute less
agreements have increased due to global awareness of the problem

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