The carbon cycle
The carbon cycle is... the exchange of carbon between the atmosphere, terrestial biosphere, oceans and sediments
We measure carbon in Pentagrams (Pg)
The terrestrial part of the carbon cycle is where plants take in carbon dioxide through photosynthesis and releases it through respiration and decomposition of dead matter.
In the oceans, carbon is held in dissolved form and in ocean organisms
The geological carbon cycle
This natural cycle moves carbon between the land, the oceans and the atmosphere.
Within the cycle, there is usually a natural equilibrium between production and absorption, however there are disprutions
An example would be an extremely large volcanic eruption which emits a large amount of carbon in the atmosphere
Important stores and fluxes
- Rocks containing carbon get subducted at boundaries and re-emerge in volcanic eruptions
- Carbon sediments are transported to the oceans via rivers. They are then deposited
- Terrestrial carbon is released through volcanic eruptions as CO2
- Acid rain dissolves rocks rich in carbon, causing chemical weathering and releasing bicarbonates
- Carbon in organic matter sinks to the ocean floor, building up layers of coal, chalk and limestone
- Heating along subduction boundaries alters sedimentary rocks, creating metamorphic rocks. This released CO2 from rocks which are carbon rich
The bio-chemical carbon cycle
The amount of carbon released or stored is determined by biological and chemical processes
CO2 is exchanged between the atmosphere and oceans >
Photosynthesis plants remove CO2 from the atmosphere >
Respiration (animals consume plants and release CO2 into the atmosphere and water >
Decomposition (the decomposition of dead plants and animals releases CO2 into soils and deposits carbon on the sea floor) >
Combustion (burning fossil fuels and releases CO2 into the atmosphere) >
The removal and storage of carbon from the atmosphere.
It occurs through photosynthesis and is held in oceans, forests and soils.
It is crucial because it prevents too much carbon being in the atmosphere and helps to regulate the planetary temperature balance.
The movement of carbon in the ocean is controlled by:
- Carbon cycle pumps - they deliver carbon dioxide to the sea floor and ocean surface
- Thermahaline circulation - a global system of surface and deep water currents within the ocean that are driven by differences in temperature
Terrestrial carbon stores
Terrestrial carbon is found in plants, animals, soil and micro-organisms
Green plants are known as primary producers. The absorb and convert carbon during photosynthesis. When the plants grow, they release the carbon back to the atmosphere through respiration.
Primary consumers (bugs, bettles, larve and herbivores) feed on producers and return carbon through respiration.
Other organisms feed on dead plants, animals and waste and are biological decomposers.
The Greenhouse Effect creates rainfall and temp va
> Solar energy is recieved from the sun. Dark surfaces on Earth absorb sunlight and some is reflected back into space.
> Some absorbed heat leads to melting, increasing the surface area of the oceans, leading to the albedo affect.
> The greenhouse gases in the atmosphere act like a blanket to trap some of the heat and keep the Earth warm
> CO2 is the most common greenhouse gas and it has the highest radiative forcing effect - this means it holds onto heat for longer
Why does temp vary around the world?
The amount of solar insolation varies at different locations
The angle of the sun's rays means isolation at the equator is more intense
At the poles this energy has to spread out over wider surface areas
The variation in surfaces also changes how much heat is absorbed or reflected
Light surfaces reflect heat and dark surfaces absorb heat
Why does precipitation vary around the world?
The temp of the atmosphere and Earth's surface controls rainfall:
> Intense equatorial heat creates low pressure systems and high rainfall levels
> At 30 degrees north and south of the equator, rainfall is low due to high air pressure
> In the mid latitudes air masses converge with low pressure systems bringing rainfall
> Close to the poles air is dense and dry so rainfall is low
How does carbon regulate the atmosphere
- Phytoplankton in the ocenas sequester CO2 through the process of photosynthesis
- Terrestrial photosynthesis enables plants to sequesters 100-120 Gt of CO2 a year
- Tropical rainforest climates are ideal for plant growth, which promotes photosynthesis
Soil and carbon
- Carbon is vital in soils
- Without cabron, the nutrient and water cycle cannot operate properly
- The amount of organic carbon stored within soil = inputs - outputs
> If a country is energy secure then they have access to reliable and afforable resources of energy. These may be domestic or from 'friendly' countries
> If a country imports more energy than it produces domestically, the country has an energy deficit and is energy insecure
> Some countries produce more energy than they need and are energy secure
All countries have an energy mix and so get their energy from different sources.
Where they get energy from depends on a range of factors:
- Physical availability
- Cost of resources
- Economc development
- Environmental priorities
Key energy players
- Consumers create demand - purchasing choices are usually based on price or cost
- Consumers have some power over oil companies
- The expansion of nuclear energy as well as fracking in the UK is controversial
- Its members are oil producing and exporting countries where oil is their main export and is vital for the social and economic welbeing
- OPEC's mission is to co-ordinate and unify the petroleum policies of its members, to ensure the stabalisation of oil in order to secure: an efficient economic and regular supply of petroleum for consumers, a steady income for producers
Key energy players
- They meet international obligations, whilst securing energy supplies for nations present and future
- Danish gov made agreements with Norway, Sweden and Germany to ensure energy security
- TNCs that supply energy keep trade flowing through established pathways and controlling prices
- Many EU governments are changing to renewables to meet COs reduction targets
- TNCs making slow progress towards 'green energy'
How are coal, oil and natural gas formed?
- Most coal in Western Eurpoe and North America and formed during the Carboniferous period, when the landmass of which these regions formed a part was located within the tropics
- Oil and natural gas are generally younger than coal and were formed during the Mesozoic era
- Forming from fossil remains of plants and animals that died and were buried
Definition = the flow of energy between a producer and a consumer
- There are several major pathways. These pathways depend on the multilateral (between countries) and bilateral (between two countries) agreements
- Some countries/companies build energy pathways which avoid transit sites in order to make them secure
- Major pathways includes - Nord Stream, The Yamal Eurpoe Pipeline, Kazakhstan - China
Unconventional fossil fuels
Unconventional sources are produced using different methods:
- Deep water oil - as we use up accessible reserves, companies are lookng into deeper ocean waters, such as the Gulf of Mexico. This is risky and expensive
- Tar sands - these are a mixture of sand, clay, water and bitumen
- Shale gas - methane or natural gas which is held in underground sandstone and shale
- Oil shale - deposits of kerogen in sedimentary rocks that haven't yet become oil
Alternatives to fossil fuels
Hydrogen fuel cells
- Could replace fuel or natural gas
- Only waste product is water
- More efficient in cars
- Example - The Mirai
- However, takes a lot of energy to get hydrogen in a pure form
Carbon capture and storage
- Collects CO2 emissions from places such as power plants and then injects it into reliable geological structures
- Example - The Boundary Dam in Canada
- However, there are issues such as CO2 leakage which could affect human health and increase underground pressure
Alternatives to fossil fuels 2
- Don't have much of a distance range
- Charging points are scattered (in the UK there are 3,919 to serve 60,000 vehicles)
- They reduce air pollution, have zero carbon emissions and are cheap to run
- Where two or more atomic nuclei fuse to make a larger nucleus and lots of energy is released in the process of diffusion
- Very clean
- 35 countries working to develop this technology