EQ1: how does the carbon cycle operate to maintain planetary health?

Question 1

describe the different forms that carbon can exist in, depending on the store

Answer 1

• atmosphere: as carbon dioxide (CO2) and carbon compounds such as methanols (CH2)
• hydrosphere: as dissolved CO2
• lithosphere: as carbonates in limestone, chalk and fossil fuels, as pure carbon in graphite and diamonds
• biosphere: as carbon atoms in living and dead organism

Question 2

what are carbon fluxes and flows measured in?

Answer 2

pentagrams or gigatoness per year.

Question 3

what are the two main geological origins of carbon?

Answer 3

• the formation of sedimentary carbonate rocks (limestone) in oceans.
• derived from plants and animals in shale, coal, and other rocks

Question 4

give an example of carbon resulting from the formation of sedimentary rocks in oceans

Answer 4

the Himalayas form one of the earths largest carbon stores. This is because the mountains started life as ocean sediments, rich in calcium carbonate derived from crustaceans, corals and plankton. Since these sediments have been unfolded, the carbon they contained has been weathered, eroded and transported back to he oceans

Question 5

describe how carbon is derived form plants and animals, coal and other rocks

Answer 5

these rocks were made up to 300 million years ago from the remains of organisms. these remains sank to the bottom of rivers, lakes and seas and were subsequently covered by silt and mud. as a consequence, the remains continued to decay anaerobically and were compressed by further accumulations of dead organisms and sediment. the subsequent burning of these fossil fuels has, of course, released the large amounts of carbon they contained back in the atmosphere.

Question 6

define the carbon cycle

Answer 6

the cycle by which carbon moves from one earth sphere (atmosphere, hydrosphere, lithosphere and biosphere) to another. It is a closed system but is made up of interlinked subsystems which are open and have inputs and outputs.

Question 7

define carbon stores

Answer 7

carbon stores function as sources (adding to carbon in the atmosphere), and sinks (removing carbon from the atmosphere).

Question 8

define carbon fluxes

Answer 8

(also known as flows or processes) are movements of carbon from one store to another; they provide the motion in the carbon cycle.

Question 9

what are the two natural geological processes of releasing carbon

Answer 9

• carbon dioxide in the atmosphere reacts with moisture to form sea carbonic acid. when this falls as rain, it reacts with some of the surface minerals and slowly dissolve them i.e there is chemical weathering
• pockets of carbon dioxide exist in the Earth’s crust. Volcanic eruptions and earthquakes can release these gas pockets. This outgassing occurs mainly along mid-ocean ridges, subduction zones at a magma hotspot.

Question 10

define chemical weathering

Answer 10

the decomposition of rock minerals in their original position by agents such as water, oxygen, carbon dioxide and organic acids.

Question 11

define outgassing

Answer 11

the release of gas previously dissolved, trapped or frozen or absorbed, in some material (e.g rock)

Question 12

define carbon sequestration

Answer 12

the process by which carbon dioxide is removed from the atmosphere and held in solid or liquid form. it is the process that facilitates the capture and storage of carbon

Question 13

what is the largest carbon store?

Answer 13

ocean (the oceanic store of Carbon is 50 times bigger than the atmospheres)

Question 14

what is most of the oceanic carbon stored in?

Answer 14

-marine algae
-plants
-coral
the rest occurs in dissolved form

Question 15

what is a carbon pump?

Answer 15

the processes operating in the oceans that circulate and store carbon

Question 16

what are the three types of oceanic carbon pumps?

Answer 16

• biological pumps
• physical pumps
• carbonate pumps

Question 17

describe biological pumps in the ocean

Answer 17

Move carbon dioxide from the ocean surface to marine plants (phytoplankton) by processes known as photosynthesis. this effectively converts carbon dioxide into food for zooplankton (microscopic animals) and their predators. most CO2 is taken up by phytoplankton and around 30% sinks into deeper waters before being converted back into carbon dioxide by marine bacteria.

Question 18

describe physical pumps in the ocean

Answer 18

more carbon compounds to different parts of the ocean in downwelling and upwelling currents. downwelling occurs in those parts of the ocean where cold, denser water sinks. These currents bring dissolved carbon dioxide down to the deep ocean. once there, it moves in slow-moving deep ocean currents, part of the thermohaline circulation, return to the surface upwelling. The cold deep ocean water warms as it rises towards the ocean surface and some dissolved carbon dioxide is rebased back into the atmosphere.

Question 19

describe carbonate pumps in the ocean

Answer 19

carbonate pumps form sediment from dead organisms that fall to the ocean floor. Particularly significant here are the hard outer shells and skeletons of crustaceans, fish and corals. All are rich in calcium carbonate.

Question 20

what us phytoplankton

Answer 20

consists of the microscopic plants and plant-like organisms drifting or floating in the sea (of freshwater) along with diatoms, Protozoa and small crustaceans.

Question 21

define photosynthesis

Answer 21

the process by which green plants and some other organisms use sunlight to synthesise (extract nutrients from carbon dioxide and water).

Question 22

define the thermohaline circulation

Answer 22

the global system of surface and deep ocean currents driven by temperatures (thermo) and salinity (haline) different parts of the oceans

Question 23

what is terrestrial sequestration

Answer 23

when plants (primary producers in the ecosystem) sequester carbon out of the atmosphere during photosynthesis. in this way, carbon enters the food chains and nutrient cycle of terrestrial ecosystems. with animals, respiration, waste and death sequesters or releases carbon.

Question 24

what two time scales do carbon fluxes vary on?

Answer 24

diurnally: during the day, fluxes are positive- that is, from the atmosphere into the ecosystems; at night the reverse situation applies
seasonally: during winter, carbon dioxide concentrations increase because of the low levels of plant growth. However, as soon as spring arrives and all plants grow again, those concentrations begin to decrease until the onset of autumn.

Question 25

how much of the human bodies weight is carbon?

Answer 25

18%

Question 26

what is the biggest on-land carbon store?

Answer 26

soil (stores between 20-30% of carbon)

Question 27

what does the amount of carbon stored (sequestered or released) in soil depend on?

Answer 27

• climate: dictates rates of plant growth and decomposition; both increase with temp and precipitation
• vegetation cover: this affects the supply of dead organic matter, being heaviest in tropical rainforests and least in the tundra
• soil type: clay protects carbon from decomposition, so clay-rich soils have a higher carbon content
• land use: cultivation and other forms of soil disturbance increases the rate of carbon loss.

Question 28

what is the greenhouse effect

Answer 28

the increasing concentration of carbon in the atmosphere that is causing great concern.

Question 29

what are greenhouse gases (GHG’s)

Answer 29

primarily water vapour, carbon dioxide, methane, nitrous oxide and ozone. these gases both absorb and emit solar radiation and, in doing so, create the so-called greenhouse effect that determines global temperatures.

Question 30

describe the greenhouse effect

Answer 30

-the earths climate is driven by incoming short-wave solar radiation
-31% is reflected back into space by clouds, GHG’s and by land surface
-the remaining 69% is absorbed at the earths surface, especially by the oceans
-much of this radiation absorbed at the surface is re-radiated, as long wave radiation
-large amounts if this long-wave radiation are, however, prevented from returning into space by clouds and GHG’s
-the trapped long-wave radiation is then re-radiated back to the Earths surface.
it is the trapped, re-radiated, long-wave energy that constitutes the natural greenhouse effect and controls the mean global temperature. it also determined the distributions of both heat and precipitation.

Question 31

define net primary productivity (NPP)

Answer 31

the amount of organic matter that is available for humans and other animals to harvest or consume.

Question 32

what is a soil health

Answer 32

a state of a soil meeting its range of ecosystem functions as appropriate to its environment. depends on the amount of organic carbon stored in the soil. The storage amount is determined by the balance between the soil’s inputs (plants, animal remains) and outputs (decomposition, erosion etc).

Question 33

what has the additional co2 in the atmosphere and its impact on GHG’s effect responsible for in terms of climate change

Answer 33

• a rise in the mean global temps
• more precipitation and evaporation
• sudden shifts in weather patterns
• more extreme weather events, such as floods, storm surges and droughts
• the nature of climate change is varying from region to region- some areas are becoming warmer and drier, others wetter.

Question 34

what do the changes in climate have serious knock-on effects on

Answer 34

• sea level: this is rising because of melting ice sheets and glaciers; many major coastal cities around the world are under threat from flooding by the sea e.g Kiribati
• ecosystems: a decline in the goods and services they provide; a decline in biodiversity; changes in the distribution of species; marine organisms threatened by lower oxygen levels and ocean acidification; the bleaching of coral etc
• the hydrological cycle: increased temps and evaporation rates cause more moisture to circulate around the cycle.