Carbon Cycle

Question 1

What is the carbon cycle?

Answer 1

The exchange of carbon (gigatonnes per year) in all its forms between different storage reservoirs

Question 2

Current atmospheric CO2 concentrations have not been exceed in …

Answer 2

the past 800k years, likely not for the past 3.5Ma

Question 3

How does carbon release in the palaeocene-eocene thermal maximum and now compare?

Answer 3

x10 more carbon released now

Question 4

How much dissolved carbon does the ocean store compared to the atmosphere?

Answer 4

Ocean holds x50 more carbon

Question 5

How much dissolved carbon do marine sediments and rocks store compared to the atmosphere?

Answer 5

x100,000 more carbon

Question 6

What % of the lithosphere is made from carbon?

Answer 6

0.032%

Question 7

Who created the Gaia hypothesis and when?

Answer 7

James Lovelock, 1979

Question 8

What is the Gaia hypothesis?

Answer 8

Idea that the planet is self-regulating … perturbations can lead to positive and negative feedbacks

Question 9

What would happen if, hypothetically, we burnt all our known fossil fuels?

Answer 9

• x10 more CO2 present than pre-industrial

- temperature rise between 4.5-15ºC

Question 10

What is one fast acting uptake of CO2?

Answer 10

Photosynthesis (lock away half of the carbohydrates generated so this is not balanced by plant respiration)

Question 11

How much faster is carbon exchange with plants than geologic exchanges?

Answer 11

1000 times faster

Question 12

How much more carbon does the ocean store compared to the terrestrial biosphere?

Answer 12

19 times more carbon stored

Question 13

What is invasion?

Answer 13

Net CO2 into ocean

Question 14

What is outgassing?

Answer 14

Net CO2 out of oceans

Question 15

What is air-sea gas exchange dependent on?

Answer 15

Relative concentrations of CO2 and partial pressure

Question 16

What is the pH of sea water?

Answer 16

pH 8

Question 17

In what oceanic areas does invasion occur?

Answer 17

Downwelling zones

Question 18

In what oceanic areas does outgassing occur?

Answer 18

Off the west coast of Central America

Question 19

What is AMOC?

Answer 19

Atlantic Meridional Overturning Circulation

Question 20

Why do these patterns of invasion and outgassing occur?

Answer 20

• Invasion: water sinks taking carbon with it leaving relatively free of carbon surface waters
• Outgassing: upwelling of nutrients brings carbon rich water up to the surface

Question 21

In the Archean Eon (4 billion years ago) what was the atmosphere composed of?

Answer 21

Mainly CO2 and N2

Question 22

What lead to the slow removal of carbon from the atmosphere over billions of years?

Answer 22

Liquid water produced carbon acid (CO2 + H20) … this then reacted with silicate rocks to produce carbonates which locks away the carbon

Question 23

How much CO2 emitted since 1800 has been taken up by the oceans?

Answer 23

42%

Question 24

What is the main storage of terrestrial carbon?

Answer 24

Trees

Question 25

What happens to biomass growth rate with increased CO2?

Answer 25

• experiments show mixed results

- some show faster growth e.g. Forest pine but seems to plateau (carbon is not the only limiting factor)

Question 26

What affect does tropospheric ozone have on the land carbon sink?

Answer 26

Reduction of carbon sink (damages vegetation)… reduces ability to absorb carbon by 0.7-1.3 Gt per year

Question 27

How much carbon is stored in known fossil fuels?

Answer 27

4000 Pg (petagrams)

Question 28

How much carbon is in the atmosphere?

Answer 28

600 Pg

Question 29

What is the ocean biological pump?

Answer 29

The permanent transfer of carbon dioxide to the sea bed following uptake into the ocean, absorption by phytoplankton, consumption of phytoplankton by zooplankton then sinking of dead organisms.