carbon cycle

• geological processes - chemical weathering

  Carbon is transferred from atmosphere to biosphere and hydrosphere. Carbon in atmosphere reacts with water vapour to form a weak carbonic acid. This can create acid rain. When acid rain falls onto rocks containing calcium carbonate ( limestone ) it reacts with it, dissolving the rock. This reaction produces carbon ions which can be transported by rivers, where they are released into the ocean.
• geological processes - outgassing

  carbon dioxide stored in magma and the earths crust is released through eruptions at plate boundaries or hotspots. This release of trapped gas is called outgassing. Carbon dioxide is also released at ocean ridges or subduction zones by geysers. At these areas, metamorphism can occur ; where sedimentary rocks change into metamorphic ones under intense pressure and heat. This also released carbon dioxide into the atmosphere. large eruptions can heavily disrupt the carbon cycle
• carbon cycle - a closed biogeochemical cycle. balance of carbon inputs and outputs determines whether it is a carbon source or sink

  carbon sink - absorbs more carbon than it releases
• Stores of carbon on Earth

  • Lithosphere (99.9%)
  • Atmosphere (0.001%)
  • Hydrosphere (0.04%)
  • Biosphere (0.004%)
  • Cryosphere (less than 0.01%)
• Lithosphere


  99.9% of Earth's carbon is stored in sedimentary rocks e.g. limestone. 0.004% stored in fossil fuels, oil and coal.
• Atmosphere


  Contains 0.001% of Earth's carbon, stored as carbon dioxide and methane
• Hydrosphere


  CO2 is dissolved in rivers, lakes and oceans. Second largest store on Earth, storing 0.04% of Earth's carbon. Most carbon is found deep in the ocean
• Biosphere


  Stored in tissues of living organisms. Is transferred to soil when they die and decay. 0.004% of Earth's carbon
• Cryosphere


  Less than 0.01% of Earth's carbon. Most carbon in cryosphere is in areas of permanent frost where decomposing animals have frozen into ground
• formation of sedimentary rock

  -dead organic matter from animals and plants falls to the bottom of lakes and oceans. This becomes covered by layers of mud and silt. more layers of organic material build up and compress lower layers. Over millions of years, these layers form shale

  -can also be formed when calcified marine life dies , such as coral, and falls to the bottom of oceans. Over millions of years this forms layers which are lithified into rocks such as limestone
• fossil fuel formation - formed by deposition of organic material. Without oxygen, full decomposition cannot occur meaning that organisms decay anaerobically. If organic matter builds up faster than it decays, this can form oil, natural gas and coal.
• biological pump - microscopic single celled organisms called phytoplankton absorb carbon from atmosphere by photosynthesis. they are at the bottom of the food chain, meaning carbon is transferred by larger organisms up the food chain. Respiration can release some carbon, however it is likely to be reabsorbed by phytoplankton. when these organism die, they fall to the sea floor where carbon is transferred from organisms to the deep ocean
• carbonate pump - chemical weathering produces carbon ions which are washed out into oceans through river systems. this reacts with carbon dioxide, to form calcium carbonate which marine organisms use to produce their shells. when these organisms die they fall to the sea floor and produce carbon rich sediment through the process of sedimentation.
• Physical pump


  Cold water is denser and stores more carbon than warm water
• Physical pump


  1. Pressure causes colder water to be forced to the deeper parts of the ocean

  2. Colder water stores more carbon

  3. Colder water at higher latitudes (the poles) stores carbon
• Thermohaline circulation


  Moves warm water on the surface towards colder parts of the world
• Thermohaline circulation


  1. As warm water cools, it stores more carbon and sinks down to deeper parts of the ocean (downwelling)

  2. Colder water is forced to the surface where carbon is either released into the atmosphere or absorbed by phytoplankton (upwelling)
• Carbon sequestration


  Carbon sequestered into plants and soils
• Photosynthesis


  Carbon produces oxygen and glucose for plants to grow new structures
• Carbon transfer through food chain


  1. Carbon passed to primary and secondary consumers

  2. Some carbon converted into proteins and fats

  3. Some carbon released for respiration and decomposition
• Respiration


  1. Breaks down glucose for energy

  2. Releases water and carbon
• Biological decomposition


  1. Fungi and animals that feed on dead material breakdown animal waste

  2. Stores carbon in soil-organic carbon
• Inorganic carbon in soil


  Comes from the breakdown of limestone
• cycle of carbon between soil and atmosphere

  bedrock is broken up

  nutrients of rock are absorbed by plant/tree roots

  vegetation grows and synthesises

  leaf litter is created

  plants and animals die and decompose

  worms and micro-organisms break down organic material and return it to the soil
• carbon dioxide enters the atmosphere when fossil fuels burn or decaying vegetation releases methane gas which also contains carbon.
• decomposition - transfers carbon from dead biomass tissue to the atmosphere and soil. after death, bacteria and fungi break organisms down and carbon dioxide is released into the atmosphere.
• factors that speed up/ slow down decomposition rates

  type of soil - arctic tundra is dry and lacks oxygen in comparison to tropical rainforests which are warm and moist all year round. means it will take longer to decompose.

  large, protein heavy mammal will take longer to decompose in comparison to a small plant

  heavily vegetated areas, that have deciduous trees with regular leaf litter will create a relatively high carbon content. low lying, hardy vegetation will reduce organic matter

  ploughing of farmland can cause gaseous release, losing carbon content
• some carbon is transferred to the soil in the form of hummus.

  lithology - high levels of carbon are found in clay based soils, while low levels of carbon are found in sand based soils
• players in energy security - TNC's

  TNC's have great global dominance in terms of energy. They are usually involved in most processes of production, from extracting natural resources to marketing product to consumers. TNC's are able to choose the pricing of their energy. they may vary prices per consumer. if they choose to lower prices, a price war can start.
• players in energy security - TNC's

  TNC's may be partially or fully state owned. For example, the Russian government controls 50% of Gazprom and all of its production processes including selling gas. State owned TNC's have power to put privately owned TNC's out of the energy market or they can use them to form political alliances whereby they provide low-price energy to potential ally
• players in energy security - governments

  governments initiate trade deals with other countries to secure reliable nd low-price supplies of energy. They may invest in national energy infrastructure projects such as power stations or dams to become more self-suffiecient on energy production. They form political alliances with countries and groups, such as opec, to ensure that energy supply isn't jeopardised by war or conflict.
• players - governments part 2

  They may encourage people to be more energy efficient through campaigns. They also regulate the activities of private energy companies to ensure consumers are charged fair prices. International protocols/agreements (Kyoto protocol/Paris agreement) may pressure governments to invest in renewable energy to reduce carbon emissions
• players - OPEC (organisation of petroleum exporting countries)

  consists of 13 countries aiming to influence the global supply and price of oil. Main member countries include Saudi Arabia, Iraq and Iran. in 2021, they had control over 80% of oil reserves. The countries collectively produce 32 million barrels of crude oil a day. they aim to stablilise oil market, and not be influenced by supply and demand. To do this, they may hold oil off the market in order for prices to remain high. However, recent competition through USA who is fracking oil means they have had to lower prices
• players - consumers.

  arguably have the least power as they have no influence over energy supply or the price they pay. However, they influence demand and how much energy TNC's or groups like OPEC need to produce. As lifestyles change ( e.g growing middle class in china) the demand for supply may go up as they use it for more luxury goods.
• players - consumers part 2

  however, in more recent years they have more influcnce as people are becoming environmentally aware and campaigning for renewable energy sources. This can put TNC's out of business as more people protest against fracking and opt for wind turbines, solar panels etc.
• Factors affecting energy security

  economic development - developing countries may have an abundance want supply of energy sources but cannot afford to extract or distribute energy to homes and businesses due to expenses and technology needed. people in developed countries will have more disposable income meaning they require more energy for cars, or to run infrastructure such as railway stations
• factors affecting energy security

  physical availability and access

  some countries have higher domestic energy supples e.g sources of oil/natural gas. less investment is needed to transport energy from producers to consumers. urban spaces usually have energy infrastructure that allows for a constant supply while rural areas have a more intermittent supply. Political tensions can affect trade of energy between countries ( Ukraine and Russia). some areas are more suited for energy production e.g situated near a river means country can produce hydroelectric power.
• The Amazon rainforest plays an important role in regulating the local, regional and global climate systems
• Amazon drought events


  1. Releases moisture into the atmosphere through evapotranspiration

  2. Affects humidity and rainfall patterns

  3. Photosynthesis slows down and less carbon is removed from the atmosphere

  4. Forest wildfires become more common, releasing more carbon dioxide into the atmosphere and increasing local atmospheric temperatures further
• Climate change can alter evapotranspiration and rainfall patterns within tropical rainforests