A-Level Geography: The Carbon Cycle KEY TERMS

Question 1

Carbon

Answer 1

One of the most chemically versatile of all the elements. Forms more compounds than any other element. It is found in all life forms in addition to sedimentary rocks, diamonds, graphite, coal and petroleum (oil and gas).

Question 2

The carbon cycle

Answer 2

The complex process carbon undergoes as it is transformed from organic carbon (the form found in living organisms such as plants and trees) to inorganic carbon and back again.

Question 3

Carbon Dioxide (CO2)

Answer 3

A gas found in the atmosphere, soils and oceans. We study this in the most detail.

Question 4

Methane (CH4)

Answer 4

Gas is found in the atmosphere, soils and oceans and sedimentary rocks.

Question 5

Calcium Carbonate (CaCO3)

Answer 5

A solid compound found in calcareous rocks, oceans and in the skeletons and shells of ocean creatures.

Question 6

Hydrocarbons

Answer 6

Solids, liquids or gases are usually found in sedimentary rocks.

Question 7

Bio-molecules

Answer 7

Complex carbon compounds are produced in living things. Proteins, carbohydrates, fats & oils and DNA are examples.

Question 8

Gigatonne

Answer 8

The most common unit is used to measure carbon. 1 is equivalent to one billion tonnes.

Question 9

Transfer/flux

Answer 9

Measure in gigatonnes/year (Gtc/yr). The movement of carbon between stores.

Question 10

Anthropogenic CO2

Answer 10

Carbon dioxide is generated by human activity.

Question 11

Biosphere

Answer 11

The total sum of all living matter. This can be divided into the terrestrial biosphere (3,170 GtC) and the oceanic biosphere.

Question 12

Carbon sequestration

Answer 12

The capture of carbon dioxide from the atmosphere or capturing anthropogenic (human) CO2 from large-scale stationary sources like power plants before it is released into the atmosphere. Once captured, the CO2 gas (or carbon portion of the CO2) is put into long-term storage.

Question 13

Carbon sink

Answer 13

A store of carbon absorbs more carbon than it releases.

Question 14

Greenhouse Gases (GHGs)

Answer 14

Any gaseous compound in the atmosphere is capable of absorbing infrared radiation, thereby trapping and holding heat in the atmosphere.

Question 15

Lithosphere

Answer 15

A rigid layer is made up of the uppermost part of the mantle and the crust. Carbon is distributed between the marine sediments (100 million GtC), soil organic matter (1500 GtC), fossil fuel deposits (4,100 GtC) and peat (250 GtC).

Question 16

Weathering

Answer 16

The breaking down of rocks and other materials on the Earth’s surface by biological, chemical or mechanical processes.

Question 17

Euphotic Zone

Answer 17

The upper layer of a body of water through which sunlight can penetrate and support photosynthesis. Contains approximately 900 GtC of carbon.

Question 18

Twilight Zone

Answer 18

A layer of water under the sunlight zone extends to 3000 feet compliantly dark no light very high-pressure near-freezing temps no plant life. Contains approximately 37,100 GtC of carbon.

Question 19

Living vegetation

Answer 19

19% of the carbon in the Earth’s biosphere is stored in plants (20% of this is stored in the Amazon rainforest). Much of this carbon is stored directly in the tissue of plants.

Question 20

Plant litter

Answer 20

This is defined as the fresh, undecomposed and easily recognisable (by species and type) plant debris. This can be anything from leaves, cones, needles, twigs, bark, seeds, nuts etc. Leaf tissues account for 70% of the debris in forests.

Question 21

Hummus

Answer 21

This originates from litter decomposition. It is a thick brown or black substance that remains after the most organic litter has decomposed. It gets dispersed through the soil by soil organisms such as earthworms.

Question 22

Organic carbon

Answer 22

Relating mainly to carbon compounds derived from biological sources. Also refers to carbon sources other than simple carbonates and carbon dioxide, such as hydrocarbons.

Question 23

Inorganic carbon

Answer 23

Carbon is extracted from ores and minerals e.g carbon dioxide, carbonic acid, bicarbonate anion, and carbonate.

Question 24

Peat

Answer 24

An accumulation of partially decayed vegetation or organic matter that is unique to natural areas called peatlands or mires. It covers 4 million km2 or 3% of the land and freshwater surface of the planet; they occur on all continents. It is estimated that they store 250 GtC worldwide.

Question 25

Animals

Answer 25

These play a small role in the biosphere. They are important in the generation of movement in the carbon through the carbon cycle.

Question 26

The Keeling Curve

Answer 26

A graph made over the span of 50 years shows the increase of carbon dioxide concentrations in the atmosphere.

Question 27

The Geological Component of the Carbon Cycle

Answer 27

Where the carbon cycle interacts with the rock cycle in the processes of weathering, burial, subduction and volcanic eruptions.

Question 28

Photosynthesis

Answer 28

Energy from sunlight is used to combine carbon dioxide from the atmosphere with water to form carbohydrates. These carbohydrates store energy. Oxygen is a by-product that is released into the atmosphere.

Question 29

Respiration

Answer 29

The process by which cells break down simple food molecules to release the energy they contain.

Question 30

Decomposition

Answer 30

A chemical reaction that breaks down compounds into simpler products. The process of decomposition is carried out by decomposers.

Question 31

Oceanic carbon pump

Answer 31

The oceans are called this because they cycle carbon from the deep waters to surface waters and the atmosphere through the process of vertical deep mixing.

Question 32

Vertical deep mixing

Answer 32

The most important movement of CO2 in the oceans. The process by which warm water from the tropics is carried to the polar regions, where it sinks and takes the CO2 with it as it cools. When it warms again, the water rises and releases CO2 into the atmosphere.

Question 33

Carbon Pump

Answer 33

Any part of the carbon cycle that moves carbon to the next part of the cycle.

Question 34

Biological carbon pump

Answer 34

The action of organisms moving carbon in one direction

Question 35

Combustion

Answer 35

When any organic material is reacted (burned) in the presence of carbon dioxide, water and energy. The organic material can be any vegetation or fossil fuel.

Question 36

Biomass combustion

Answer 36

The burning of living and dead vegetation. It includes human-induced burning as well as naturally occurring fires.

Question 37

Deforestation

Answer 37

The removal of trees. This is driven by the need for extra agricultural land and logging. 13 million ha (approximately) - an area the size of Greece - of the world’s forests are being cut down every year.

Question 38

Afforestation

Answer 38

The planting of trees.

Question 39

Urban growth

Answer 39

The rate of increase of urban populations. The urban population is expected to reach 60% by 2030. Urban areas are growing at a rate of 1.3 million people every week.

Question 40

Terrestrial or biological sequestration

Answer 40

This involves the use of plants to capture CO2 from the atmosphere and then store it as carbon in the stems and roots of the plants as well as in the soil.

Question 41

Carbon budget

Answer 41

The balance of the carbon exchanges between carbon sinks and sources.

Question 42

Ocean acidification

Answer 42

About 30% of the CO2 that has been released into the atmosphere has diffused into the ocean through the direct chemical exchange. Dissolving CO2 in the ocean creates carbonic acid. This makes the slightly alkaline ocean become a little less alkaline. Since 1750, the pH of the ocean’s surface has dropped by 0.1, a 30% change in acidity.

Question 43

Enhanced greenhouse effect

Answer 43

The impact on the climate from the additional heat retained due to the increased amounts of CO2 and other greenhouse gases that humans have released into the Earth’s atmosphere since the industrial revolution.

Question 44

Soil organic carbon (SOC)

Answer 44

The organic constituents in the soil: are tissues from dead plants and animals, products produced as these decompose and the soil microbial biomass.

Question 45

Carbon capture and sequestration (CCS)

Answer 45

A technology that can capture up to 90% of CO2 emissions produced from the use of fossil fuels in electricity generation and industrial processes, preventing the CO2 from entering the atmosphere. The CCS chain consists of capture, transporting and storing.