the carbon cycle

Question 1

what is the carbon cycle?

Answer 1

a complex process that carbon goes through as it is transformed from organic carbon to inorganic carbon and back again.

Question 2

what is carbon?

Answer 2

it is one of the most chemically versatile elements, forming more compounds than any other element.

Question 3

where is carbon usually found?

Answer 3

in all life forms, as well as sedimentary rocks, diamonds, graphite, coal, oil and gas.

Question 4

why is carbon important?

Answer 4

it is needed by all plants and animals to survive.\

recycling for carbon is essential for life on earth; enables food to be provided for plants and animals and energy sources are created to fuel industrial development.

Question 5

what are the main stores of carbon?

Answer 5

• lithosphere
• hydrosphere
• cryosphere
• atmosphere
• biosphere

Question 6

what is a carbon sink?

Answer 6

a store that absorbs more carbon than it releases.

Question 7

what is a carbon source?

Answer 7

a store that releases more carbon than it stores.

Question 8

what is meant by a carbon transfer?

Answer 8

these are processes that transfer carbon between the stores. transfers such as inputs and outputs affect the size of the carbon stores.

Question 9

what is meant by anthropogenic carbon dioxide?

Answer 9

carbon dioxide generated by human activity.

Question 10

what is the lithosphere?

Answer 10

the crust and uppermost mantle; this constitutes the hard and rigid outer layer of the earth.

Question 10

what is weathering?

Answer 10

the breakdown of rocks by a combination of weather, plants and animals.

Question 11

what is the biosphere?

Answer 11

the total sum of all living matter.

Question 12

what was the primary source of carbon?

Answer 12

the earths interior. it was stored in the mantle when earth formed and escapes at constructive and destructive plate boundaries.

some of the carbon remains as CO2 in the atmosphere, some is dissolved in oceans, some is held as biomass in living or dead organisms and some is found in rocks.

Question 12

what is carbon sequestration?

Answer 12

the capture of co2 from the atmosphere OR capturing anthropogenic co2 from industry like power plants and capturing it before it is released into the atmosphere.

Question 13

what are the global stores of carbon in the terrestrial ecosystem?

Answer 13

the largest stores are typically found in North America, with more than 500 tonnes of carbon in selected areas.

areas with little to no carbon storage are in parts of northwest africa. perhaps due to the fact that there are many desert areas (not ideal conditions for carbon storage).

Question 14

what is the hydrosphere?

Answer 14

all of the water on the earth’s surface.

Question 14

what is the lithosphere?

Answer 14

the rigid part of the earths crust.

Question 15

what is the biosphere?

Answer 15

the part of the planet occupied by living things.

Question 16

what is the cryosphere?

Answer 16

frozen water part of the earth’s system.

Question 17

what is the atmosphere?

Answer 17

all the gasses that are around the planet.

Question 18

what is the pedosphere?

Answer 18

the outermost layer of the earth that is composed of soil and subject to soil formation processes.

Question 19

what kind of system is the carbon cycle?

Answer 19

a closed system

Question 20

why is the carbon cycle a closed system?

Answer 20

there are inputs and outputs of energy, but the amount of carbon stays the same.

carbon moves from one store to another in a continuous cycle. the processes by which the carbon moves between these stores are known as transfers or fluxes.

some carbon is locked away in long term stores, e.g. rocks and fossils.

Question 21

what are carbon stores or stocks?

Answer 21

the total amount of the material of interest held within a part of the system.

this is effectively how much of the material there is and where it is.

Question 22

what are carbon fluxes?

Answer 22

measurements of the rate of flow of material between the stores. because fluxes are a rate, the units are mass per unit time.

Question 23

what are carbon processes?

Answer 23

the physical mechanisms which drive the flux of material between stores.

for example, one of the key processes which drive the flux of carbon from the atmosphere to the vegetation store is photosynthesis.

Question 24

what processes transfer carbon?

Answer 24

• photosynthesis
• respiration
• decomposition
• burial and compaction
• carbon sequestration
• ocean take up and loss (carbon pumps)
• weathering

Question 25

how does photosynthesis transfer carbon?

Answer 25

plants move carbon from the atmosphere into the biosphere through photosynthesis.

they use energy from the sun to chemically combine co2 with hydrogen and oxygen from water to create glucose.

Question 25

how does respiration transfer carbon?

Answer 25

carbon enters the atmosphere as carbon dioxide from respiration. it returns carbon dioxide to the atmosphere by breaking down sugars.

exhalation reduces co2 gas.

Question 26

how does decomposition transfer carbon?

Answer 26

when the animals die, they decompose, and their remains become sediment, trapping the stored carbon layers that eventually turn into rock or minerals.

Question 27

how does burial and compaction transfer carbon?

Answer 27

when organic matter is buried by sediment it becomes compacted.

over millions of years, these organic sediments containing carbon may form hydrocarbons like coal and oil.

Question 27

how does combustion transfer carbon?

Answer 27

transferring carbon dioxide from the biosphere into the atmosphere.

the burning of fossil fuels release carbon that has sequestered in geological formations for millions of years.

Question 28

how does carbon sequestration transfer carbon?

Answer 28

it takes atmospheric carbon and stores in underground geological formations or rocks.

Question 29

how do carbon pumps transfer carbon?

Answer 29

transfers carbon from the surface of the ocean to the deep ocean.

formation and sinking of calcareous skeletal material by some marine phytoplankton and animals.

ocean takes up carbon dioxide through photosynthesis by plant-like organisms and co2 dissolving in water.

it reacts with saltwater, creating carbonic acid.

Question 30

how does weathering transfer carbon?

Answer 30

rock weathering moves carbon from the atmosphere into the lithosphere by dissolving rocks, washing the constituents into the oceans depositing new sediment on sea floor.

Question 31

how can the carbon cycle change?

Answer 31

it can be transferred from one store to another in a matter of seconds (wildfires) whilst others can take millions of years (deep ocean).

there are both human and physical causes of this.

Question 32

when was the quaternary period?

Answer 32

2.6 million years ago to this day.

global climates have fluctuated massively between interglacial and glacial periods.

Question 33

what are the natural causes that change the carbon cycle?

Answer 33

• wildfires
• volcanic activity
• milankovitch cycles

Question 34

how can wildfires impact the carbon cycle?

Answer 34

lightening strikes can start wildfires naturally. despite being restricted to tiny parts of the surface, they can have regional impacts.

wildfires relate a large amount of carbon dioxide into the atmosphere.

for example, in 1997/8 and 2003, Indonesia had many wildfires that burnt out of control for months at a time.
the smoke spread across south-east Asia and caused a noticeable strike in carbon emissions.

Question 35

how can volcanic activity impact the carbon cycle?

Answer 35

• volcanic eruptions release carbon that have been trapped in the lithosphere for millions of years.

during the palaeozoic era, volcanoes were much more active than they are today. co2 was therefore emitted into the atmosphere where it remained for a long time.

now - volcanoes emit 130-180 million tonnes o c02 each year whereas human activity =30 billion tonnes from burning fossil fuels.

Question 36

how can milankovitch cycles affect the carbon cycle?

Answer 36

as temperatures start to rise at the end of the glacial periods there is a surge of co2 released into the atmosphere by melting ice.

this surging of co2 then enhances the greenhouse effect, warming the trend.

Question 37

what impact do colder conditions have on the carbon cycle?

Answer 37

• cold rainwater can hold more co2
• forest coverage is different, affecting the significance and distribution of processes such as respiration and photosynthesis.
• decomposers less effective so carbon transfers to the soil are reduced.
• more water stored as ice and less is transferred to oceans. less sediment along river and floor.
• soil is frozen over vast areas, stopping co2 transfer.

Question 38

what impact do warmer conditions have on the carbon cycle?

Answer 38

melting of permafrost
|
releases previously trapped gases, such as methane which is now being released.
|
enhances greenhouse effect
|
positive feedback system leading to further destabilisation of systems.