Carbon cycle and carbon in the earth system

Question 1

Terrestrial C is cycled between

Answer 1

reservoirs on the land and in the atmosphere (mainly as CO2)

Question 2

On land, C occurs primarily

Answer 2

in living biota and decaying organic matter, particularly in the soil (photosynthesis and respiration: growth and decay).

Question 3

CO2 emissions from land use change are calculated by

Answer 3

using a book-keeping method based on Food and Agriculture Organization of the United Nations (FAO) assessments of land-use change, i.e., from governmental reports. The uncertainty on land use change emissions is the highest of any flux component of the global carbon budget

Question 4

Changes in land use are measured using

Answer 4

remote sensing, government statistics, and carbon stores and fluxes are estimated from empirical
observations.

Question 5

How is it that the ocean can take in more CO2 if atmospheric concentrations rise, and the ocean is a net sink?

Answer 5

In the ocean mixed layer, HCO3- (bicarbonate, 91%) and CO3 2- (carbonate, 8%) form a buffer system, moving CO2 out of the water into other compounds.

Question 6

What is the mechanism known as the ‘solubility pump’?

Answer 6

As more carbon dioxide can dissolve in cold water than in warm, cold dense waters sinking at high latitudes are rich in carbon and act to move large quantities of carbon from the surface to deep waters.

Question 7

How does seawater accommodate the

addition of an acid or base without appreciable pH change?

Answer 7

The ocean’s carbonate-bicarbonate buffer system buffers the increased concentration of hydrogen ions that results from elevated levels of dissolved
CO2 in surface waters.