Carbon cycle

Question 1

Sink vs source

Answer 1

Sink: net going in of carbon
Source: net going out of carbon

Question 2

Carbon in biota roughly equals carbon in ATM

so..

Answer 2

Change in growth vs destruction of vegetation can alter the carbon balance—variable year-to-year

Question 3

Carbon in ocean mixed layer roughly equals carbon in ATM

so…

Answer 3

Ocean can absorb extra carbon
– ‘Missing’ anthropogenic CO2 – in ocean?
– Deep ocean reservoir - once in ocean sediments, C is locked
up

Question 4

Stores of carbon in the terrestrial system

Answer 4

Living biomass (photosynthesis)
Soil organics (especially peatlands)
Organic compounds in permafrost
Fossil fuels (oil, coal, gas)

Question 5

Human impacts on land-atmosphere carbon flux

Answer 5

Burning of fossil fuels (industrialisation)
Forest clearance and land cover change
Episodic release of CO2 via burning for clearance and icnreased decay rates
Agricultural practices e.g. ploughing, wet rice cultivation
Reforestation/ afforestation (temporary increase co2)
Uptake by regrowth/ young plantations

Question 6

What direction are natural and anthropogenic fluxes?

Answer 6

Natural fluxes are variable and bi-directional

Anthropogenic fluxes are largely unidirectional

Question 7

What is the highest of any flux component of the global carbon budget?

Answer 7

The uncertainty on land use change emissions

Question 8

Until the 1980s, land use accounted for more increase in GHG than…

Answer 8

fossil fuel burning.

Question 9

What can be used to analyse climate changes?

Answer 9

Tree ring data

Thawing northern permafrost

Question 10

Carbon in the ocean

Answer 10

Ocean mixed layer dissolved inorganic carbon (DIC) <1% is dissolved CO2

Most DIC is in a buffering system
Carbon dioxide dissolves to form carbonic acid, which dissociates into ions of 2 valencies (plus protons, H+) and hold a lot of Co2 that’s not Co2 (has several different ionic identities in water)

Question 11

Implications of buffering

Answer 11

1. Buffering prevents back pressure from ocean carbon dioxide
2. Ocean can “take in” extra atmospheric CO2
3. Acidification slowed, but still occurs

Question 12

OCEAN ACIDIFICATION

Answer 12

Production of more biocarbonate buffer soaks up some of the H+ but not all, and the consequence is that there is less CO3 2- .
This critical for shell-making fauna and corals that use CO3 2 – ocean acidity is reaching levels that may affect physiological function