Uncertainties of predictions of future atmosphere CO/sub 2/ concentrations
Linear carbon cycle models, tuned to reproduce the CO/sub 2/ increase observed at Mauna Loa, independently of their individual assumptions, predict almost identical CO/sub 2/ concentration trends for fossil energy scenarios assuming a slightly increasing production in the next few decades. The basic information for such prognoses therefore is the airborne fraction observed over the last 20 years. Uncertainties in this quantity are due to possible errors in the estimate of fossil fuel consumption and the corresponding CO/sub 2/ emission, possible natural fluctuations in the baseline CO/sub 2/ level, and uncertainties regarding the biospheric CO/sub 2/ input and uptake as a result of deforestation and reforestation and land management. Depending on different assumptions the effective airborne fraction, defined as the ratio of CO/sub 2/ increase due to fossil fuel CO/sub 2/ alone to the integrated CO/sub 2/ production, might be as low as 0.38 or as high as 0.72, compared to the apparent airborne fraction of 0.55. The effective airborne fraction derived from carbon cycle models, considering only the CO/sub 2/ uptake by the ocean, lies in the range 0.60--0.70. A value as low as 0.40 seems therefore highly improbable. A high biospheric anthropogenic CO/sub 2/ input therefore must have been accompanied by a high CO/sub 2/ fertilization effect. Model considerations, however, are not in contradiction with a high biospheric input with the maximum production before 1958, which also would imply low preindustrial CO/sub 2/ concentrations in the range 270--280 ppm as reported recently.
- Research Organization:
- Physics Institute, University of Bern, Bern, Switzerland
- OSTI ID:
- 6152422
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 88:C2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON DIOXIDE
CONCENTRATION RATIO
EARTH ATMOSPHERE
AIR-WATER INTERACTIONS
BIOSPHERE
CARBON CYCLE
FOSSIL FUELS
SENSITIVITY ANALYSIS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
ENERGY SOURCES
ENVIRONMENT
FUELS
OXIDES
OXYGEN COMPOUNDS
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)