The Carbon Cycle

Question 1

What percentage of carbon on earth is contained within the lithosphere? What does this equate to? What about fossil fuels?

Answer 1

Over 99.9% of carbon is contained within the lithosphere
This equates to 100,000,000 PgC
0.004% of this is contained within fossil fuels

Question 2

What are some examples of the 1. sedimentary rocks 2. Fossil fuels and 3. Pure carbon minerals that carbon are contained within on earth?

Answer 2

Sedimentary: limestone, shale, chalk

Fossil fuels: coal, oil and natural gas

Pure carbon minerals: graphite, diamond

Question 3

What is the smallest and most sensitive store if carbon on earth, what proportion of carbon is stored here?

Answer 3

The atmosphere, 0.001% of carbon is stored here

Question 4

How is limestone formed?

Answer 4

She’ll fragments (e.g. plankton, snails, crabs and lobster)
These die and shell fragments precipitate to the ocean floor
Organic material buried under other organic material
Increase in pressure and compaction from overlying sediment layers causes shells to be lithified to limestone (forms rock)

Question 5

How is shale formed?

Answer 5

Organic material precipitates to ocean floor
Organic matter is buried by mud
Material becomes embedded within the layers of mud
Intense heat and pressure
Causing lithification to shale (form of mudstone)

Question 6

How are fossil fuels formed?

Answer 6

Organic matter precipitates to ocean floor / river bed and covered by mud
Mud causes material to decay anaerobically (no oxygen)
If organic matter added faster than it can decays it becomes a fossil fuel
Oil + gas formed from dead marine plants + animals
Coal formed from dead plants (trees +ferns)
This process can often occur in peatlands

Question 7

What is the pH of the weak carbonic acid in chemical weathering?

Answer 7

PH=5.6

Question 8

What is dissolved during chemical weathering?

Answer 8

Calcium carbonate which is the binding agent in limestone

Question 9

At what rate of carbon ions carried into the oceans via solution?

Answer 9

0.1-0.2 PgC/yr

Question 10

What are these carbon ions used by in the oceans (chemical weathering)?

Answer 10

They are incorporated into the shells of crustaceans

Question 11

At what rate does carbon escape from volcanic outgassing and what is Europe’s most active outgassing volcano?

Answer 11

0.1-0.5PgC/Yr, Mt Etna

Question 12

What are the characteristics of a balanced carbon cycle?

Answer 12

The atmospheric store contains 600 PgC
31% of solar radiation is reflected by clouds + aerosols back into space
GHGs (CO2 + CH4) absorb IR radiation and reradiate it in all directions this maintains atmospheric temperatures at 15 degrees C (habitable)
Dominated by negative feedback mechanisms

Question 13

What are the characteristics of an unbalanced carbon cycle?

Answer 13

Atmosphere contains 800PgC
Human interference = increased greenhouse effect = greater temps
Dominated by positive feedback mechanisms

Question 14

How much more potent of a greenhouse gas is methane than carbon dioxide?

Answer 14

30x more potent

Question 15

Why is the southern ocean significant when considering the physical pump?

Answer 15

Responsible for 25% of water sequestered by oceans

Question 16

Why is more carbon sequestered in polar oceans?

Answer 16

Cold water has an increased ability to absorb and sequester carbon dioxide

Question 17

What are some examples of currents created by the pulling of water from the tropics to the poles?

Answer 17

The Gulf Stream and the North Atlantic Drift

Question 18

How much has global temperature increased since the end of the Industrial Revolution?

Answer 18

1.1 degrees Celsius

Question 19

What effect will increasing ocean temperature have on phytoplankton, where can this be seen?

Answer 19

Increasing temperature kills phytoplankton as they thrive in cool nutrient rich waters, phytoplankton have decreased in the Indian Ocean by 20% in the last 60 years

Question 20

What is the evidence for ocean acidification (Ocean pH)

Answer 20

Current ocean pH = 8.1
Industrial era pH = 8.2

Question 21

How could greater ocean temperatures affect corals? How could this affect the oceans role as a carbon sink?

Answer 21

Corals stop growing at pH 7.8, this is predicted to occur by 2050
This reduces the growth of coral dependant sea grass meadows, which capture carbon 35x faster than tropical rainforests

Question 22

How could coral bleaching affect economies?

Answer 22

Decreased tourism
Releases zooxanthella, causes ciguatera poisoning in fish and therefore in humans
Kiribati relies on this fishing for 26% of their economy
Great Barrier Reef = $6.4 Bln to Australian economy (90% of this is tourism related)

Question 23

How could rising sea levels (from EGHE) result in positive feedback?

Answer 23

Fewer coral reefs in photic zone = decreased photosynthesis = increased CO2 remaining in the atmosphere = increased EGHE

Question 24

How can EGHE affect Peruvian fish stocks?

Answer 24

Increased frequency + intensity of ENSO cycles
Increased El Niño means the Humboldt current cannot rise off of Peru
45% reduction in fish stocks compared to a normal year

Question 25

How can EGHE influence local flood risk?

Answer 25

For storm surge data see oceans notes
1 degree C increase in temp causes a 7% rise in the amount of water the atmosphere can hold = greater monsoons
Ganges- Brahmaputra delta inundated with water from heavier conventional rainfall

Question 26

How could EGHE affect humans (via oceans)?

Answer 26

For SLR see oceans notes
Saltwater intrusion (from SLR)
Decreasing agricultural yields from saline soils as seen in Vietnamese Mekong river delta