Carbon Cycle Content

Question 1

What is the geological carbon cycle?

Answer 1

natural long term cycle
The movement and storage of carbon between land, oceans and the atmosphere
closed system
There is a general balance between production and absorption (sources and sinks)- however it sometimes it takes a long time for equilibrium to be reached (after a volcanic eruption)

Question 2

What are the inputs and outputs of the carbon cycle?

Answer 2

Inputs:
-Volcanism= releases C02
-Metamorphism of carbonate rocks= releases C02 into atmosphere (subduction zones)
-Calcium carbonate deposition= releases C02 into atmosphere

Outputs:
-Animal shells/skeletons= carbon used to form them
-Limestone= shells and skeletons compacted to form limestone
-Coal= decaying vegetation forms coal
-Sandstone/shales= sand and clays from rivers compacted to form this

Question 3

How is carbon absorbed and produced

Answer 3

Carbon absorption-sedimentation
Carbon production-degassing/outgassing

Question 4

How does the carbon cycle maintain equilibrium?

Answer 4

Chemical weathering lays an important role in the carbon cycle father disruptions such as major volcanic eruption

1. C02 released into atmosphere after eruption
2. atmospheric C02 combines with rainfall to form acid rain
3. acid rain dissolves carbonate rocks (limestone become bicarbonates)
4. bicarbonates enter rivers and eventually oceans
5. bicarbonates are compacted on the ocean floor as rock= geological sink

Question 5

What forms does carbon exist in?

Answer 5

-Inorganic (rocks as bicarbonates and carbonates)
-Organic (found in plant material and living organisms)
-Gaseous (found as CO2 and CH4/methane)

Question 6

What are stores of the caron cycle?

Answer 6

terrestrial, oceanic or atmospheric:
-atmosphere as CO2 and methane
-hydrosphere as dissolved CO2
-lithosphere as carbonates in limestone and fossil fuels
-biosphere in living and dead organisms
Caron sink= any store that takes in more carbon that it emits
Carbon source= any store that takes in less carbon than it emits

Question 7

What is carbon sequestration?

Answer 7

transfer of carbon from the atmosphere to other stores
can be natural or artificial

Question 8

What are the main carbon stores? What is their magnitude?

Answer 8

1.Sedimentary rocks (Lithosphere)= 66,000 to 100,000 million billion metric tonnes
2. Oceans (Hydrosphere)= 38,000 million metric tonnes
3. Fossil fuel deposits (Lithosphere)= 4000 billion metric tonnes remain as fossil fuels.
4. Soil organic matter (Lithosphere)= 1500 billion metric tonnes of carbon
5. Atmosphere= increase of around 40% since industrial revolution 750 billion metric tons
6. Terrestrial plants (Biosphere)= 560 billion metric tons of carbon

The lithosphere is the main store of carbon. Global stores are unevenly distributed

Question 9

What are fluxes?

Answer 9

transfers in the carbon cycle
drive and cause changes to the carbon cycle over time
all have impacts of varying magnitude over different lengths o f time

Question 10

What are the variations in fluxes?

Answer 10

Carbon moves through the pathways in the carbon cycle very quickly whereas other pathways are much slower

fastest= land biota to atmosphere- absorption via photosyneyhsis release via respiartion
slowest= absorption via sedimentation and release via chemical weathering

Question 11

What is the bio=geochemical carbon cycle?

Answer 11

living organisms are critical in maintaining the carbo cycle, they control this by:
-photosynthesis
-respiration
-decomposition
-combustion

Question 12

How do photosynthesis and respiration influence the carbon cycle?

Answer 12

Photosynthesis:
Plants sequester carbon and convert it into oxygen and glucose using light energy
helps to maintain the balance between 02 and CO2 in the atmosphere

Respiration:
plants and animals convert oxygen and glucose into energy which produces water and CO2

During the day pants photosynthesise= absorbing more C02 than they emit through respiration
At night they do not photosynthesise but still respire so release more C02 than they absorb
overall plants are net carbon dioxide absorbers and net oxygen producers

Question 13

How does combustion influence the carbon cycle?

Answer 13

When fossil fuels and organic matter=emit CO ₂into atmosphere , may occur when fossil fuels are burnt to produce energy, or if wildfires occur.

Question 14

How does decomposition influences the carbon cycle?

Answer 14

When organisms die, they are broken down by decomposers 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.

Question 15

How does diffusion influence the carbon cycle?

Answer 15

oceans can absorb CO ₂ from the atmosphere
This has increased ocean acidity by 30% since pre-industrial times which is harming aquatic life by causing coral bleaching.

Question 16

How does sedimentation influence the carbon cycle?

Answer 16

happen on land or in the sea.
Organic matter from vegetation and decaying marine organisms is compacted over time, whether on land or in the sea, to form fossil fuel deposits
e.g., when shelled marine organisms die, their shell fragments fall to the ocean floor and become compacted over
time to form limestone.

Question 17

How does weathering and erosion influence the carbon cycle?

Answer 17

Chemical weathering: Carbonation=occurs when CO ₂ in the air mixes with rainwater to create carbonic acid which aidserosion 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

Question 18

How does metamorphosis influence the carbon cycle?

Answer 18

Extreme heat and pressure forms metamorphic rock, during which some carbon is released and some becomes trapped.

Question 19

How does volcanic outgassing influence the carbon cycle?

Answer 19

There are pockets of CO2 found in the Earth’s crust.
During a volcanic eruption this CO2 can be released.

Question 20

What are the variations in the carbon cycle?

Answer 20

-quickest cycle (seconds)= plants absorb carbon for photosynthesis and release carbon when respire

-longest= dead organic material may hold carbon for hundreds of years- may become buried so deeply they don’t decay and become sedimentary rocks

biological processes exchange carbon more quickly than geological processes

Question 21

What are carbon reservoirs and reservoir turnover?

Answer 21

Reservoir= store of carbon
Reservoir turnover= length of time carbon stays in a reservoir

Question 22

How do oceans store carbon?

Answer 22

largest carbon stores
93% of CO2 stored in oceanic algae, plants and coral
transfer of CO2 into sea= ocean sequestration

Majority of processes which take CO2 out of atmosphere and into ocean occur at top surface layer
this carbon rich surface layer is then transferred down into lower layers and transported through thermohaline circulation

Question 23

What are phyloplankton?

Answer 23

Microscopic organisms that like plants photosynthesise.
take in carbon and turn it into organic matter
half of the planets biomass consist of phyloplankton
base of marine food web so when they get eaten carbon is passed through the food chain

Question 24

What is the biological carbon pump?

Answer 24

Some organisms like plankton sequester C02 turning the carbon into their hard outer shells and inner skeletons
Some of their shells dissolve in the water= carbon becomes part of deep ocean currents
any dead organisms will sink to seafloor= become buried and compressed= forming limestone sediments (sedimentation)
^ over time this can turn into fossil fuels

Question 25

What is the physical carbon pump?

Question 26

What is thermohaline circulation?

Answer 26

an ocean current that produces both vertical and horizontal circulation of cold and warm water around the world’s oceans.
rate of circulation is slow
1. begins in polar oceans where water is very cold, surrounding seawater sinks due to a higher density.
2. current is recharged as it passes Antarctica by extra cold, salty, dense water.
3. Division of the main current; northward into the Indian Ocean and into the Western Pacific.
4. The two branches warm and rise as they travel northward then loop back southward and
westward.
5. The now warmed surface waters continue circulating around the globe.
6. On their eventual return to the North Atlantic they cool and the cycle begins again.

Question 27

What factor affects absorption of CO2 into oceans?

Answer 27

Ocean temperatures
Colder the water=more C02 absorbed
so increased ocean temperatures will absorb less C02 accelerating climate change

Question 28

What is terrestrial sequestration?

Answer 28

primary producers sequester carbon through photosynthesis
when consumers eat plants carbon is converted into fats and proteins
micro-organisms feeds on waste material from animals and plants
(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

Question 29

How do carbon fluxes vary due to terrestrial organisms?

Answer 29

Diurnally= during the day fluxes are positive from the atmosphere to the ecosystem during the night they are negative

Seasonally= in northern hemisphere during winter plants die and decay leading to high atmospheric C02 but during spring when plants begin to grow C02 levels in atmosphere drop

Question 30

How is forest cover changing over the years?

Answer 30

-southern hemisphere= declining
-northern hemisphere= growing
-rate of forest has decreased since 1990’s from 9.5 to 5.5. million hectares
-Brazil has the most carbon stored on land and the most extensive deforested area
-China has the largest amount of afforested area

Question 31

What is the soils capacity to store carbon?

Answer 31

-store 20-30% of world’s carbon
-most long term process is the formation of humus= 60% contains carbon
Factors affecting soil capacity:
-climate= affects plant growth and microbial activity
-soil type= clay>sandy
-use of soils= land use and disturbance can affect how much carbon is held

Question 32

What is the natural greenhouse effect?

Answer 32

-earths temp control system relies on greenhouse gases in atmosphere
-earths climate driven by shortwave solar radiation
-around 31% of carbon is reflected by clouds and gases in 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
Constant levels of C02 help to maintain stable temperature
before industrial revolution natural green house effect was constant

Question 33

What is the enhanced green house effect?

Answer 33

-since 1750s green house gas conc has increased by more than 25%
-75% from burning fossil fuels
-has led to more carbon being released into atmosphere and less being absorbed

Question 34

What human activities shave led to the enhanced green house effect?

Answer 34

-Land use change: deforestation for cattle ranching= methane e.g 70% of deforestation in Amazon is for cattle
-Deforestation: reduces carbon sequestration- accounts for 20% of all greenhouse emissions
-Urbanisation= cement releases high levels o CO2 during production
-Combustion= C02, sulphur released into atmosphere (estimated using fossil fuels has added more than 180Gt of carbon to the atmosphere)

Question 35

What are the implications of the enhanced greenhouse effect?

Answer 35

Climate:
-In Europe expected to increase more than global average
-largest temp increase expected in Eastern and Northern Europe during winter and Southern Europe in summer

Question 36

What is energy security?

Answer 36

Energy security is achieved when there is an uninterrupted availability of energy at a national level and at an affordable price.
-most secure= national demand for energy can be completely satisfied by domestic sources. (less risks from economic and geopolitical changes)
Four key aspects:
-availability
-accessibility
-affordability
-reliability

Question 37

How is energy consumption measured?

Answer 37

-per capita
-energy intensity (units of energy per unit GDP)- the fewer the units the more efficient

Question 38

What is the energy mix?

Answer 38

combination of different energy resources used to meet a country’s total energy consumption

Primary energy= refers to natural energy resources that have not been converted into another form of energy e.g. coal, oil etc.
Secondary energy= refers to what the primary resource has been converted to usually electricity

Question 39

What factors affect the energy mix of a country?

Answer 39

-physical availability
-cost
-technology
-political considerations
-environmental priorities

Question 40

How do we classify energy into 3 groups?

Answer 40

Renewable= energy resources that are not depleted as they are used
Non renewable= finite energy resources that can become completely exhausted
Recyclable= fuel that can be used to generate power more than once