Sources and Sinks of Carbon Dioxide

Abstract

The conventional representation of the impact on the atmosphere of the use of fossil fuels is to state that the annual increases in concentration of CO₂ come from fossil fuels and the balance of some 50% of fossil fuel CO₂ is absorbed in the oceans or on land by physical and chemical processes. An examination of the data from:

i) measurements of the fractionation of CO₂ by way of Carbon-12 and Carbon-13 isotopes,

ii) the seasonal variations of the concentration of CO₂ in the Northern Hemisphere

and

iii) the time delay between Northern and Southern Hemisphere variations in CO₂,

raises questions about the conventional explanation of the source of increased atmospheric CO₂. The results suggest that El Nino and the Southern Oscillation events produce major changes in the carbon isotope ratio in the atmosphere. This does not favour the continuous increase of CO₂ from the use of fossil fuels as the source of isotope ratio changes. The constancy of seasonal variations in CO₂ and the lack of time delays between the hemispheres suggest that fossil fuel derived CO₂ is almost totally absorbed locally in the year it is emitted. This implies that natural variability of the climate is the prime cause of increasing CO₂, not the emissions of CO₂ from the use of fossil fuels.