EQ1 - How does the carbon cycle operate? Flashcards
1
Q
What is the carbon cycle?
A
How carbon moves from one sphere (atmosphere, hydrosphere, lithosphere and biosphere) to another.
2
Q
What type of system is the carbon cycle?
A
A closed system
- input and output levels remain constant
- however it is made up of interlinked ‘open’ subsystems
3
Q
What are the 2 main components in the carbon cycle?
A
- Stores
- Fluxes/flows
4
Q
What 2 functions do stores have which contribute to the carbon cycle?
A
- Act as sources (adding carbon to the atmosphere)
- Act as sinks (removing carbon from the atmosphere)
5
Q
What are fluxes/flows and how do they contribute to the carbon cycle?
A
Flows are the movement of carbon from one store to another
- provide the motion in the carbon cycle
6
Q
In the atmosphere, how does carbon exist?
A
As CO2 and as carbon compounds (e.g methane)
7
Q
How is carbon stored in the hydrosphere?
A
As dissolved carbon dioxide (e.g in oceans)
8
Q
How is carbon stored in the lithosphere (ground)?
A
As carbonate (e.g limestone, chalk, fossil fuels) and as pure carbon (e.g diamonds)
9
Q
How is carbon stored in the biosphere?
A
As carbon atoms in living and dead organisms
10
Q
Do the characteristics of carbon stores vary?
A
Yes - they vary in size, capacity, and locations
11
Q
What types of locations does the biosphere include for carbon storage?
A
Both terrestrial and ocean locations
12
Q
What are the 2 units of measurement used to measure carbon flows?
A
Petagrams (Pg) or gigatonnes (Gt, per year
13
Q
Where do most of the major fluxes in the carbon cycle occur? (2)
A
- Between oceans and atmosphere
- Between land and atmosphere (via photosynthesis + respiration)
14
Q
Do carbon fluxes vary? How?
A
Yes - vary in terms of amount of flow and timescale
15
Q
Where is most of the carbon in the world stored?
A
Rocks
16
Q
What type of rocks store the highest amounts of carbon?
A
Carbonate rocks
17
Q
What is the name of the carbonate rock, formed in the ocean, that holds lots of carbon?
A
Limestone
18
Q
What sort of environment is needed for sediment deposition?
A
Low-energy
- so that sediment falls to the sea bed
19
Q
Define ‘diagenesis’ ?
(sedimentation process)
A
The physical and chemical changes that occur during the conversion of sediment to sedimentary
20
Q
What is ‘litigation’?
(sedimentation process)
A
The conversion of loose, unconsolidated sediment into solid rock
21
Q
What % mass of limestone is pure carbon?
A
40%
22
Q
What % of lithospheric (ground) carbon is found in limestone?
A
80%
23
Q
Limestone is formed when sodium carbonate is deposited on the ocean floor.
True or False?
A
False - its formed when calcium carbonate is deposited
24
Q
How did the Himalayas become a carbon store?
A
The Himalayas used to be underwater, therefore ocean sediments are present, rich in calcium carbonate
25
What happens to carbon in the Himalayas over time?
It is weathered, eroded, and transported back to the oceans
26
What do rocks like shale and coal consist of?
Dead plants and animal matter
27
How are carbon-rich rocks formed?
Dead remains decay without oxygen and are compressed by sediment layers above
28
How old are rocks like shale and coal?
Up to 300 million years old
29
What releases carbon stored in fossil fuels?
Burning the fossil fuels
30
How can carbon dioxide in the atmosphere contribute to chemical weathering?
It reacts with moisture to form weak carbonic acid (acid rain)
- this can dissolve surface minerals
31
Define chemical weathering?
The decomposition of rock minerals in their original position by water, oxygen, CO2, and organic acids
32
Where are pockets of carbon dioxide found in the Earth?
In the Earth's crust
33
What geological events can release carbon dioxide from the Earth's crust?
Volcanic eruptions and earthquakes
34
What is outgassing?
Release of gas that was previously dissolved, trapped, frozen, or absorbed in materials like rock
35
Where does outgassing mostly occur?
Along mid-ocean ridges, subduction zones, and at magma hotspots
36
Biological sequestering operates on a much longer timescale than geological sequestering
True or False?
False - much shorter timescale, from hours to centuries
37
How many times more is the oceanic store of carbon than that stored in the atmosphere?
50x
38
The Oceans are the largest carbon store.
True or False?
False - they are 2nd behind the lithosphere
39
What are the 3 types of oceanic carbon pump?
1. Biological pumps
2. Physical pumps
3. Carbonate pumps
40
What do oceanic carbon pumps do?
Circulate and store carbon
41
What do biological pumps do?
Move carbon dioxide from the ocean surface to marine plants (phytoplankton) through photosynthesis
42
How do biological pumps create food in oceans?
They convert CO2 into food for zooplantic (microscopic animals) and their predators
43
Where is most of the CO2 taken up by phytoplankton recycled?
Near the water surface
- around 30% sinks into deeper waters before being converted back to CO2 by marine bacteria
44
Explain how Physical pumps work
They move carbon compounds to different parts of the ocean through downwelling/upwelling currents
45
Explain downwelling (physical pump)
Where cold, denser water sinks bringing dissolved carbon dioxide down to the deep ocean
- once there, it moves in slow-moving currents, remaining for 100s of years
46
Explain upwelling (physical pump)
Deep ocean currents (holding dissolved CO2) return to the surface
- as the water warms and rises SOME dissolved CO2 is released back into atmosphere
47
Explain Carbonate pumps
These form sediments from dead organisms on the ocean floor
- usually out of skeletons of fish or corals (rich in calcium carbonate)
48
Define the thermohaline circulation
The global system of surface and deep ocean currents, driven by temperature and salinity differences within the ocean
- can be seen as a giant conveyor belt
49
How do plants sequester carbon?
Out of the atmosphere through photosynthesis
50
How does carbon enter the food chain and nutrient cycles?
When animals consume plant matter, the carbon sequestered within the plant becomes part of their fat and protein
51
How does carbon enter micro-organisms?
Micro-organisms (bacteria and fungi) eat animal waste
52
What happens to carbon when micro-organisms die?
Carbon is released into the soil as remains decompose
53
How do carbon fluxes vary diurnally (during the course of a day) ?
Carbon moves into ecosystems during the day (photosynthesis) and out at night (respiration)
54
How do carbon fluxes vary seasonally?
CO2 rises in winter (low plant growth) and falls in spring/summer (high plant growth)
55
What % is the human body made up of carbon by weight?
18% carbon
56
What is the largest carbon store on the land, and how much does it store?
Soils store 20% to 30% of global carbon
57
How is carbon stored in soils?
In the form of dead organic matter
58
How much more carbon does soil sequester than the a) the atmosphere and b) vegetation
a) 2x more than the atmosphere
b) 3x that of vegetation
59
What 4 factors can impact the actual amount of carbon stored in soil?
1. Climate
2. Vegetation cover
3. Soil type
4. Land use
60
How does climate affect the amount of carbon stored in soil?
Higher temperatures/more rainfall increases plant growth and decomposition
61
How does vegetation cover affect the amount of carbon stored in soil?
More vegetation = more dead organic matter
- most organic matter in rainforest, least in tundra
62
How does soil type affect the amount of carbon stored in soil?
Clay protects carbon from decomposition
- clay-rich soils have a higher carbon content
63
How does land use affect the amount of carbon stored in soil?
Soil disturbance (e.g cultivation) increases the rate of carbon loss
64
What link is the carbon cycle so important in providing?
The link between all the spheres
- atmosphere, hydrosphere, lithosphere, biosphere
65
What are considered the 2 most important greenhouse gases?
Carbon Dioxide and Methane
66
What happens to solar radiation entering Earth's atmosphere? (greenhouse effect)
Some is absorbed by Earths surface, warming it; some is reflect back into space
67
What do greenhouse gases do in the greenhouse effect?
They absorb and re-emit infrared radiation, trapping heat in the atmosphere
68
What is the overall result of the greenhouse effect?
It warms Earth's surface and the troposphere
69
What % of short-wave solar radiation is reflected back into space?
31%
- reflected by clouds, GHGs and the land surface
70
What % of short-wave radiation is absorbed by the earth's surface?
69% - especially absorbed by oceans
71
What does short-wave radiation become once it is re-radiated by the earths surface?
Long-wave radiation
72
What happens to large amounts of long-wave radiation?
It is prevented from returning to space by clouds and GHGs
- becomes TRAPPED
73
How does the natural greenhouse effect control mean global temperature?
Trapped long-wave energy (heat) warms the atmosphere and surface
74
Why does the natural greenhouse effect influence heat distribution?
Trapped heat drives air circulation, directing heat around the planet
75
Why does the natural greenhouse effect influence precipitation distribution?
Trapped heat causes evaporation and influences air movement, which shapes rainfall patterns
76
How does photosynthesis help regulate Earth's temperature?
Keeps CO2 levels stable
77
What is net primary production (NPP)?
The amount of organic matter that is available for humans/animals to harvest or consume
78
Where is net primary production (NPP) highest and lowest?
High in warm, wet areas (e.g rainforests, shallow oceans)
Low in cooler, dry areas (e.g tundra)
79
What does soil health depend upon?
The amount of organic carbon stored in the soil
80
How is the amount of organic carbon is soil determined?
The balance between soil's inputs (plant/animal remains) and outputs (decompostion, erosion and plant uptake)
81
How does surface soil erosion affect soil health?
Even small amounts of erosion reduce organic carbon and nutrients
- this can devastate soil health and fertility
82
What period in history (mid 18th century) marked the start of increased fossil fuel use for energy?
The Industrial Revolution
83
What is the number one threat to the global carbon cycle?
Fossil fuel combustion
84
How much of the CO2 caused by the Industrial Revolution has remained in the atmosphere?
Around 50%
- the rest has been absorbed (fluxed) by carbon stores
85
What are some climate changes caused by additional CO2 in the atmosphere?
1. Rising global temperatures
2. Increased precipitation and evaporation
3. Changing weather patterns
4. More extreme events (e.g floods and droughts)
86
How does climate change vary regionally?
Some regions are warmer and drier; others getting wetter
87
What main knock-on effect has climate-induced rising sea levels had?
Major coastal cities threatened by flooding
- due to melting of ice sheets/glaciers
88
What 3 Hmain impacts has climate change had on ecosystems?
1. Reduced biodiversity
2. Marine organisms threatened (ocean acidification, lower oxygen)
3. Decline in the goods/services they provide
89
How does climate change affect the hydrological cycle?
Increased temperatures and evaporation - led to more moisture circulating in the cycle
90
