Global Warming

38 The greenhousegases

345 350 355 360 365 370 375 380 385

− 60

− 55

− 50

− 45

− 40

− 35

− 30

− 25

− 20

1990

1992

1994

1996

1998

2000

1991

1993

1995

1997

1999

atmospheric

increase

land

uptake

ocean

uptake

outgassing

fossil

fuel

bur ning

O^2

concentration, difference from standard (ppm)

CO 2 concentration (ppm)

Figure 3.4Partitioning of fossil fuel carbon dioxide uptake using oxygen

measurements. Shown is the relationship between changes in carbon dioxide

and oxygen concentrations. Observations are shown by solid circles and

triangles. The arrow labelled ‘fossil fuel burning’ denotes the effect of the

combustion of fossil fuels based on the O 2 :CO 2 stoichiometric relation of the

different fuel types. Uptake by land and ocean is constrained by the

stoichiometric ratio associated with these processes, defining the slopes of the

respective arrows.