3.1.1.3 carbon cycle W&C Flashcards
what is the major source of carbon
the earths interior, it was stored in the mantle when the earth was formed
where does carbon escape from the mantle
plate boundaries as well as hot spots
where is carbon distributed in the world
CO2 in the atmosphere
dissolved in the oceans
held in biomass in living or dead organisms
in carbonate rocks
how is carbon put into long term storage
by burial and compaction of sedimentary rock layers including coal, shale and limestone
how is the amount of carbon measured
in gigatonnes
1 gigatonne is the equivalent to 1 billion tonnes
what is carbon found in
all life forms as well as sedimentary rocks, diamonds, graphite, coal, oil and natural gas
why is the recycling of carbon essential for life on earth
enables food to be provided for plants and animals and energy sources to be created for industrial development
what are some important carbon compounds
CO2
CH4 (methane)
CaCO3 (calcium carbonate)
hydrocarbons
what subsystems is carbon found in
lithosphere, atmosphere, hydrosphere, biosphere and cryosphere
how much carbon is stored in the lithosphere
over 99.9%
how much carbon is in the atmosphere
0.001%
how much carbon is in the hydrosphere
0.04%
how much carbon is in the biosphere
0.004%
how much carbon is in the cryosphere
less than 0.01%
what are transfers/fluxes
carbon moving from one store to another in a continuous cycle
what is a net carbon sink
more carbon enters than leaves
what is a net carbon source
more carbon leaves than enters
what are the 7 major carbon flows
photosynthesis, respiration, decomposition, combustion, weathering, ocean uptake and loss (diffusion) and sequestration
what is photosynthesis + extra detail for 4 marker
the transfer of carbon stored in the atmosphere to biomass
plants and phytoplankton use energy from the sun to change CO2 and water to glucose and oxygen which allows them to grow
CO2+H2O+sunlight > CH2O+O2
Carbon is then passed through the food chain and released through respiration and decomposition.
what is respiration + extra detail
the transfer of carbon from living organisms to the atmosphere
Plants and animals break down glucose for energy, releasing CO2 and methane (which contains carbon) in the process
Respiration is the opposite of photosynthesis, these processes are not in balance however. Not all organic matter is oxidized. Some is buried in sedimentary rocks
what is decomposition + extra detail
transfer carbon from dead biomass to the atmosphere and the soil
After death, bacteria and fungi break organisms down. CO2 and methane are released
Some carbon is transferred to the soil in the form of humus
Decomposition ensures that carbon can be continually recycled into the soil and made available for life
what is combustion + extra detail
the transfer of carbon stored in living, dead or decomposed biomass to the atmosphere by burning
occurs when any organic material is burned in the presence of oxygen to five of CO2, water and energy
the organic material includes any vegetation or fossil fuel such as natural gas, oil or coal
what is weathering + extra detail
chemical weathering transfers carbon from the atmosphere to the hydrosphere and biosphere
atmospheric carbon reacts with water vapour to form mildly carbonic acid, this acid rain falls onto rocks and a chemical reaction occurs to dissolve the rocks, this may be washed away to sea where it reacts with CO2 dissolved in the water to form calcium carbonate which is used by sea creatures to make their shells
what is ocean uptake and loss (diffusion) + extra detail
CO2 is directly dissolved from the atmosphere to the ocean, it may be taken up by organisms that live in the water such as plankton
carbon is also transferred to the oceans when carbon rich water from deep in the oceans rises to the surface and releases CO2
what is sequestration + extra detail
carbon from the atmosphere can be sequestered (captured and held) in sedimentary rocks or as fossil fuels, this effectively puts carbon into long term storage
Rocks and fossil fuels form over millions of years when dead animals and plant material in the ocean falls to the floor and is compacted
how does carbon change in stores over time
some carbon flows are relatively fast (photosynthesis and respiration) whereas some are much slower (it takes millions of years for carbon to be sequestered into sedimentary rocks)
how does carbon change in stores over scale
occur at plant scale, seral scale, ecosystem scale and continental scale
what is primary succession
when bare rock is colonised by plant and animal communities over time, at the climax community the cycling of carbon is greater than at the beginning
what are the two changes to the carbon cycle over time due to natural variation
Wildfires and volcanic activity
how do wildfires cause change to the carbon cycle over time
They rapidly transfer large quantities of carbon from biomass (or soil) to the atmosphere as a result of combustion
As wildfires result in a loss of vegetation in the short term, photosynthesis decreases so less carbon is removed from the atmosphere.
In the longer term, however, fires can encourage the growth of new plants. Secondary succession can occur as plants recolonise the area. As succession takes place more carbon will be taken from the atmosphere as a result of photosynthesis
how does volcanic activity cause change in the carbon cycle over time
Carbon stored within the Earth in magma is released during volcanic eruptions. The majority enters the atmosphere as CO. This returns carbon that has been trapped for millions of years in rock deep
Recent volcanic eruptions have released much less CO2, than human activities (e.g. fossil fuel burning). At present, volcanoes emit between 130 and 380 million tonnes of CO2 per year
what are the 4 changes in the carbon cycle of time due to human activity
Hydrocarbon fuel extraction and burning, deforestation, urbanisation and land use change
what are hydrocarbons
fossil fuels are composed of carbon and hydrogen so are known as hydrocarbons
how does hydrocarbon fuel extraction and burning cause change in the carbon cycle over time
Extracting and burning (combustion) of fossil fuels releases CO2 into the atmosphere.
Without human intervention, the carbon would remain sequestered in the lithosphere for
thousands or millions of years to come
Today, most of the world’s gas and oil is extracted from rocks that are 70-100 million years old.
The carbon has remained locked up in these deposits for all that time but, when burnt to generate energy and power, the stored carbon is released as CO2 into the atmosphere, accelerating the cycling of this carbon
Since the industrial revolution fossil fuels have been burnt in increasing quantities
According to the Intergovernmental Panel on Climate Change (IPCC), about 90% of the anthropogenic (human related) carbon release comes from the combustion of fossil fuels, primarily coal, but also oil and gas
how do farming practices cause change in the carbon cycle over time
Agricultural activities release carbon dioxide into the atmosphere:
livestock release C02 and methane when they respire and digest food, this is the largest source of C02 within agriculture
Ploughing releases carbon stored in the soil, air is mixed in when soil is turned which increases soil microbial activity, results in soil ,alter being broken down more rapidly
Growing rice in rice paddies releases a lot of methane. This helps accounts for over 40% of agriculture-related greenhouse gas outputs occur in Asia
As the world’s population has risen, so has food production. As a result, carbon emissions from farming practices have increased. Mechanisation of farming has also increased CO2 emissions as more tractors and other farm vehicles are used across the globe
how has deforestation cause change in the carbon cycle over time
Forests may be cleared for agriculture, logging, or to make way for development and urban sprawl
The UN Food and Agriculture Organisation (FAO) estimates that about 13 million hectares (an
area the size of Greece) of the world’s forests are cut down and converted to other land uses
every year.
if the cleared forest is burned, there is a
rapid flow of carbon from the biosphere to the atmosphere
how does land use change cause change in the carbon cycle over time
the change of land use from natural or agricultural to urban is a major source of carbon. Replacing open countryside with concrete and tarmac is known as urbanisation
Vegetation is removed, or covered up, to make way for buildings – this reduces carbon storage in the biosphere
Globally, urban areas occupy 2% of the total land area. However, these account for 97% of all
anthropomorphic CO2 emissions
what is the carbon budget
the difference between inputs and outputs of carbon into/out of a subsystem
what is examples of the carbon budget
For example, in the atmosphere, inputs of carbon come from volcanic eruptions, burning fossil
fuels, respiration and ocean loss, and outputs occur through photosynthesis, sequestration,
decomposition, chemical weathering and ocean uptake
what does the balance of inputs and outputs determine
whether it acts as a carbon source or sink
where do natural systems ‘bank’ carbon
in biomass and by dissolution in the ocean system
why is carbon important to ‘the land’
- allows plants to grow (photosynthesis, respiration and decomposition)
- because plants are primary producers in ecosystems, all consumers including livestock and humans depend on plants
what effect would the carbon cycle have on ‘the land’
- more CO2 is available to plants and longer growing season due to warmer temps, more photosynthesis and plant growth, growth limits will depend on water and nutrient availability
- An increase in global temperatures could increase the frequency of wildfires, further increasing atmospheric CO2
why is carbon important for the ocean
- organisms such as phytoplankton and seaweed use the CO2 during photosynthesis and other marine organisms to form calcium carbonate shells and skeletons
what is the effect of carbon on the oceans
- More CO2 in the atmosphere means more acidic oceans as the oceans initially absorb more CO2 (ocean uptake). There has been a 30% change in ocean acidity since 1750. This is adversely affecting marine life, including coral reefs. Reef loss is linked to a fall in marine diversity
- Warmer oceans are certainly causing sea ice to melt. Arctic sea ice has retreated by 40% in the last 35 years. The loss of sea ice is resulting in a loss of a habitat for species of algae that support marine consumers as well as a loss of hunting grounds for larger predators like polar bears
why is carbon important for the atmosphere
- The carbon cycle affects the amount of gases containing carbon (e.g. CO2 and methane) in the atmosphere. These are greenhouse gases and ensure that the climate is warm enough to support life on Earth
what effect will carbon have on the atmosphere
- the concentration of greenhouses gases in the atmosphere increases temperatures are expected to rise causing rapid global warming. Greenhouse gas emissions have increased significantly in recent decades due to human activities such as deforestation and fossil fuel combustion. This has led to an enhanced greenhouse effect
why is carbon important for the global climate (vegetation
- Vegetation plays a pivotal role in the carbon cycle and on global climates. Plants remove carbon dioxide and release water and oxygen. Regions with dense vegetation (e.g. tropical rainforests) experience high rates of photosynthesis and respiration. This increases levels of humidity, the amount of cloud cover and affects rainfall.
- Regions experiencing large-scale deforestation may become drier and less humid
