1.4 The carbon cycle and energy security Flashcards
What is the natural carbon cycle?
the movement and storage of carbon between the land, ocean and the atmosphere.
Where is inorganic carbon found?
Found in rocks as bicarbonates and carbonates
Where is organic carbon found?
Found in plant material and living organisms
Types of carbon stores (3)
- terrestrial
- oceanic
- atmospheric
Define flux
the movement/transfer of carbon between stores.
What is a carbon sink?
any store which takes in more carbon than it emits, so an intact tropical rainforest is an example
What is a carbon source?
any store that emits more carbon than it stores so a damaged tropical rainforest is an example.
Examples of where carbon is present in stores (4)
▪ 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 organism
Describe carbon sequestration
- the transfer of carbon from the atmosphere to other stores
- can be both natural and artificial.
- For example. a plant sequesters carbon when it photosynthesises and stores the carbon in its mass.
What are the main carbon stores? (6)
- Marine Sediments and Sedimentary Rocks
- Oceans
- Fossil fuel deposits
- soil organic matter
- atmosphere
- terrestrial plants
Describe the global distribution of carbon stores in the lithosphere and biosphere
- The lithosphere is the main store of carbon , with global stores unevenly distributed.
- For example, the oceans are larger in the southern hemisphere
- storage in the biosphere mostly occurs on land.
- Terrestrial plant storage is focussed in the tropics and the northern hemisphere.
Describe transfers in the carbon cycle
- The transfers in the carbon cycle act to drive and cause changes in the carbon cycle over time.
- They all have impacts of varying magnitude over different lengths of time .
- Biological and chemical processes determine how much carbon is stored and released.
- The role of living organisms is very important in maintaining the system running efficiently.
Describe the process of photosynthesis
- Living organisms convert Carbon Dioxide from the atmosphere and Water from the soil, into Oxygen and Glucose using Light Energy.
- By removing CO ₂ from the atmosphere, plants are sequestering carbon and reducing the potential impacts of climate change.
- Photosynthesis helps to maintain the balance between oxygen and CO ₂ in the atmosphere.
Describe the process of respiration
- Respiration occurs when plants and animals convert oxygen and glucose into energy which then produces the waste products of water and CO ₂.
- It is therefore chemically the opposite of photosynthesis
Describe the balance between plant photosynthesis and respiration
- During the day, plants photosynthesise, absorbing significantly more CO ₂ than they emit from respiration.
- During the night they do not photosynthesise but they do respire, releasing more CO ₂ than they absorb.
- Overall, plants absorb more CO₂ than they emit, so are net carbon dioxide absorbers (from the atmosphere) and net oxygen producers (to the atmosphere).
Describe the process of combustion
- When fossil fuels and organic matter such as trees are burnt, they emit CO ₂ into the atmosphere , that was previously locked inside of them.
- This may occur when fossil fuels are burnt to produce energy, or if wildfires occur.
Describe the process of decomposition
- When living organisms die, they are broken down by decomposers (such as bacteria and detritivores ) which respire, returning CO₂ into the atmosphere.
- Some organic matter is also returned to the soil where it is stored adding carbon matter to the soil.
How does ocean diffusion affect ocean acidity?
- The oceans can absorb CO ₂ from the atmosphere, which has increased ocean acidity by 30% since pre-industrial times
- The ocean is the biggest carbon store, but with carbon levels increasing seawater becomes more acidic which is harming aquatic life by causing coral bleaching.
- Many of the world’s coral reefs now under threat.
Describe the process of sedimentation
- This can happen on land or in the sea.
- For example, when shelled marine organisms die, their shell fragments fall to the ocean floor and become compacted over time to form limestone.
- Organic matter from vegetation and decaying marine organisms is compacted over time, whether on land or in the sea, to form fossil fuel deposits.
Describe the processes of carbonation weathering and erosion
- Inorganic carbon is released slowly through weathering: rocks are eroded on land or broken down by carbonation weathering.
- Carbonation weathering occurs when CO ₂ in the air mixes with rainwater to create carbonic acid which aids erosion of rocks such as limestone .
- The carbon is moved through the water cycle and enters the oceans.
- Marine organisms use the carbon in the water to build their shells .
- Increasing carbon dioxide levels in the atmosphere, may increase weathering and erosion as a result, potentially affecting other parts of the carbon cycle.
Describe the process of rock metamorphosis
Extreme heat and pressure forms metamorphic rock, during which some carbon is released and some becomes trapped.
Describe volcanic outgassing
- There are pockets of CO2 found in the Earth’s crust.
- During a volcanic eruption or from a fissure in the Earth’s crust, this CO2 can be released.
Describe short-term variations in carbon fluxes
- The quickest cycle is completed in seconds as plants absorb carbon for photosynthesis and then they release carbon when they respire.
- This cycle can slow down when levels of
light or CO2 drop.
Describe longer-term variations in carbon fluxes in soil
- Dead organic material in soil may hold carbon for hundreds of years.
- Some organic materials may become buried so deeply that they don’t decay, or are buried in conditions unfavourable to decayers (potent low-lying gas, too much water).
- This material will become sedimentary rocks or hydrocarbons by geological processes.
Describe differences in carbon storage in different layers of the ocean
- The majority of the processes which take the CO2 out of the atmosphere and into the ocean occur in the top surface layer which makes up only a small proportion of the water in the world’s ocean.
- The carbon rich water in the surface layer is then transferred down into the lower layers of the ocean and transported around the world due to thermohaline circulation.
- It is this circulation which allows such large amounts of carbon to be stored in the sea
Describe the role of phytoplankton in ocean sequestation
- Phytoplankton are microscopic organisms that, like plants, photosynthesise.
- They take in carbon and turn it into organic matter.
- As they are the base of the marine food web, when they get eaten, carbon is passed through the food chain.
- CO2 is also released back into the water as these organisms respire.
Describe the role of shell-making organisms in ocean sequestation
- Some organisms like Plankton sequester CO2, turning the carbon into their hard outer shells and inner skeletons.
- When these organisms die, some of their shells dissolve into the ocean water meaning the carbon becomes part of deep ocean currents.
- Any dead organisms which sink to the seafloor become buried and compressed, eventually forming limestone sediments (sedimentation)
- Over a long time period these can turn into fossil fuels.
describe how CO2 is dissolved into oceans
- some CO2 from the atmosphere will naturally by dissolving into the water.
- This process occurs on the surface of the oceans where CO2 reacts with water to form carbonic acid.
- As the concentrations of CO2 in the atmosphere increase, oceans absorb more CO2, causing them to become more acidic.
- This acidification of the oceans could have long lasting negative effects.
- This movement of CO2 isn’t one way, some will go from the water back into the atmosphere.
- 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.
Why is the concentration of CO2 in oceans different around the world?
- the colder the water, the more CO2 is absorbed
- CO2 concentration is 10% higher in the deep ocean compared to the surface of the ocean.
- Polar regions hold more carbon than tropical regions.
- Warm tropical waters release CO2 to the atmosphere but cold high latitude oceans absorb in CO2 from the atmosphere.
Describe 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.
- 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.
- Rate of circulation is slow
- Warm surface waters are depleted of CO2 and nutrients therefore the foundation of the planet’s food chain depends on cool and nutrient rich water which support algae to grow.
How do ocean temperatures affect 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 CO2). - This would accelerate Climate Change and lead to further ocean warming (positive feedback mechanism)
Describe the carbon transfers in the food chain (3)
▪ Primary producers (plants) take carbon from the atmosphere to photosynthesise and release carbon when they respire.
▪ Vegetation growth depends on water, nutrients and sunlight.
▪ When consumers eat plants, carbon from the plants is converted into fats and proteins
Describe the carbon transfers in decomposition (3)
▪ Micro-organisms feed on waste material from animals and plants.
▪ Animal and plant remains are easier to decompose compared to wood. Decomposition is faster in tropical climates with high rainfall, temperatures and oxygen levels.
▪ 95% of a tree’s biomass consists of CO2 which is sequestered and converted to cellulose. The amount of carbon stored in trees depends on the balance of respiration and photosynthesis.
Variations in carbon fluxes due to terrestrial organisms (2)
● Diurnally – during the day, fluxes are positive from the atmosphere to the ecosystem whereas in the night, fluxes are negative from the atmosphere to the ecosystem.
● Seasonally – In the northern hemisphere during winter, plants die and decay leading to high atmospheric CO2 concentrations but during spring when plants begin to grow, CO2 levels in the atmosphere begin to drop.
How much of the world’s carbon do soils store?
20-30%
Why are arid and semi-arid soils the most important store?
- Any loss by a plant to the ground means that some carbon will transfer to the soil.
- Soil microbes break down plants release carbon to the atmosphere.
- After organisms die, thousands of compounds in soil are decomposed.
Factors affecting soil capacity to store carbon (3)
▪ Climate – this affects the rate of plant growth and microbial activity. Decomposition occurs at a fast rate in places with higher temperatures and rainfall.
▪ Soil type – Clay rich soils contain more carbon than sandy soils.
▪ Use of soils – Land use, cultivation and disturbance can affect how much carbon can be held.
Describe the natural greenhouse effect (4)
- sunlight passes through the atmosphere and warms the earth
- infrared radiation is given off by the earth
- most escapes to outer space, allowing the earth to cool
- but some infrared radiation is trapped by gases in the air (including CO2) keeping the air warm enough to sustain life
Describe the proportions of inputs and outputs of the natural greenhouse effect (4)
- Around 31% of energy is reflected by clouds and gases in the atmosphere.
- The remaining 69% is absorbed by the Earth’s surface and oceans.
- 69% of surface absorption is reradiated to space as longwave radiation
- A large proportion of longwave radiation is radiated back to the Earth by clouds & greenhouse gases
Describe levels of atmospheric carbon prior to the industrial revolution
- Before The Industrial Revolution, the natural greenhouse effect was constant.
- The slow carbon cycle, volcanism, sedimentation have been fairly constant over the last few centuries.
- Natural exchanges between the slow and fast sections of the carbon cycle were relatively small.
- There were small variations in atmospheric CO2 up until the late 19th century.
How has human activity affected the greenhouse effect?
- Since the 1750s (when industrialisation began in the UK), global concentrations of greenhouse gases like CO2 & CH4 have increased by more than 25%.
- Since the 1980s, 75% of carbon emissions have come from burning fossil fuels.
- Human activities have led to more carbon being released into the atmosphere and less being absorbed
How does land use change affect levels of atmospheric carbon?
- Accounts for a tenth of carbon release annually and impacts on short-term stores in the carbon cycle, such as the soil and atmosphere.
- Farming Practices: In the Amazon, around 70% of deforestation is for cattle ranching. Cattle produce significant amounts of methane, further contributing to global warming. Scientists are considering whether feeding cows different foods would help to reduce their methane emissions.
How do fertilisers affect atmospheric carbon levels?
- Fertilisers are a significant source of greenhouse gases as well as rice paddy fields, from which methane emissions have increased as a result of increased productivity due to higher CO₂ levels.
- More sustainable grains and seeds like quinoa are being considered as substitutes, which require less water to grow
How does deforestation affect levels of atmospheric carbon?
- In total, deforestation accounts for about 20% of all global greenhouse emissions.
- The main impact is when the cycle is interrupted and the land is used for other purposes, which then reduces carbon sequestration and land becomes a carbon source rather than a carbon sink.
How does urbanisation affect levels of atmospheric carbon?
- This is the process of replacing countryside with buildings and other similar infrastructure.
- It affects the local and global carbon cycles, by replacing vegetation and covering soils.
- Urban areas occupy 2% of the world’s land mass, but these areas account for 97% of all human caused global CO₂ emissions.
- Cement is an important building material, but releases carbon dioxide during production, contributing 7% to global carbon dioxide emissions each year, so sustainable options for recycling concrete are being developed.
How does combustion of fossil fuels affect levels of atmospheric carbon?
- This results in CO2, sulphur and particulates being released into the atmosphere.
- If combustion occurs in a hot engine, NO2 will also be released (also a greenhouse gas) as nitrogen from the air fuses with oxygen.
- It is estimated that burning fossil fuels has added more than 180 Gt of carbon to the atmosphere.
How is solar energy distributed around the Earth’s surface? (3)
- The amount of solar energy reaching the Earth varies depending on location, and is the main factor in determining climate temperatures.
- Solar intensity is more intense at the equator, and reduces as you travel towards the poles.
- The Albedo Effect will also determine the temperature of a location. Snow reflects solar radiation whereas dark forests absorb the most solar radiation.
Global distribution of impacts of the enhanced greenhouse effect (4)
● In Europe, average temperatures are expected to increase more than the global average.
● The largest increases are expected in Eastern and Northern Europe during winter and Southern Europe during summer.
● Annual precipitation is expected to increase in Northern Europe but decrease in Southern Europe.
● Extreme weather events are likely to increase in both frequency and intensity.
Describe the global distribution of convectional rainfall (4)
- Solar radiation is the most intense along the equator, so convectional rainfall is common and rainfall is generally very high.
- Where convectional rainfall is likely to occur can be understood using the ITCZ Model.
- Rainfall occurs at subtropical highs (mid-latitude) and the poles.
- Where air submerges and cools, water vapour condenses to form clouds and precipitation. Where air rises, the air heats up and moisture will evaporate. This creates dry weather conditions.
How might global warming affect certain species?
- Species with low population numbers are already at high risk. There is already evidence showing that there will be change in species’ population size, timing of reproduction and migration.
- Marine organisms are also at risk. They are threatened with low oxygen levels and high rates of acidification. The impact on coastal ecosystems and low lying areas of sea levels rising could continue.
Impacts of global warming on the Arctic (3)
- The arctic region is warming twice as fast as the global average.
- Melting permafrost releases methane and carbon dioxide which increases the concentration of greenhouse gases in the atmosphere.
- This could lead to further Global Warming and even more melting of snow and ice, establishing a positive feedback loop through a reduced Albedo effect.
Impacts of global warming on the Arctic tundra ecosystem (3)
- The Arctic tundra ecosystem has changed significantly; rapid warming has contributed to extensive melting of snow and ice during the summer months.
- Shrubs and trees which previously couldn’t live in the Arctic have began to grow.
- In Alaska, the Red Fox has now spread northwards and competes with the Arctic Fox for food and territory
Impacts of global warming on the hydrological cycle (5)
- Increased rate of evaporation could lead to more moisture being held in the atmosphere rather than in the ocean.
- Increase in surface permafrost temperatures.
- Less sea ice and glacier storage.
- Change in capacity of terrestrial ecosystems.
- Change in river discharge - increased risk of flooding in winter and droughts in summer.
Define energy security
Maximum energy security refers to the uninterrupted availability of energy sources at an affordable price.
What is the difference between long-term and short-term energy security?
- Long term energy security mainly deals with timely investments to supply in energy sources that will match economic developments and environmental needs.
- Short term energy security focuses on the ability of the energy system to react promptly to sudden changed in the balance between energy demand and energy supply.
