Sea-Level Change (1990) / Chapter Skim
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12 Long-Term Aspects of Future Atmospheric CO2 and Sea-Level Changes
12 Long-Term Aspects of Future Atmospheric CO2 and Sea-Level Changes
Pages 193-207
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From page 193... ...
Such uncertainties will probably persist for a long time to come. Perhaps, rather than trying to discern whether CO2 or climate has been cause or effect, we would do better to work toward models in which climate and the carbon cycle are considered parts of the same system.
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From page 194... ...
The time scales and magnitudes of melting ice can be estimated from both historical data and mass balance considerations. The present Greenland and Antarctic ice sheets are remnants of the late Pleistocene ice sheets that increased sea levels about 100 m by melting over a period of several thousand years encompassing the end of the Pleistocene (see Matthews, Chapter 5, this volume)
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From page 195... ...
TIME SCALES OF CARBON CYCLE CHANGE The carbon cycle can be broadly subdivided according to characteristic time scales. Figure 12.1 illustrates one such subdivision, emphasizing long-term effects.
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From page 196... ...
If all of the world's fossil-fuel resources were instantaneously added to the oceans as CO2 and distributed in proportion to present dissolved inorganic carbon concentrations, the resultant atmospheric CO2 concentration would be about three times its present value. However, if the same amount of CO2 were allowed to react with an equal molar amount of ERIC T
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From page 197... ...
Whereas nearly all CO2 predictive models treat alkalinity as a constant parameter, any ocean model that incorporates calcite dissolution must treat alkalinity as a time-dependent variable. Like dissolved inorganic carbon, alkalinity is conservative with respect to ocean mixing processes.
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From page 199... ...
Diffusive terms, which appear only in the equations for the temperate ocean boxes, have the form ~z',+~ _ 7' ~ (12.1 ~ where the subscripts i and i+1 refer to vertically contiguous boxes, X represents the concentration of either total alkalinity or total dissolved inorganic carbon, z represents the box depth, and Kv represents the vertical diffusion coefficient. Values for Kv range from 1.7 cm2/s below the temperate ocean surface mixed layer (Li et al., 1984)
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From page 200... ...
The sediment burial flux is equivalent to the difference between the sedimentation fluxes and the dissolution flux. Model calcite and noncarbonate sedimentation fluxes are assigned constant values that are consistent with the known distribution of oceanic sedimentation rates.
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From page 201... ...
The model can be tuned to yield this global burial flux exactly, with only minor adjustment of the shallow-water calcite sedimentation fluxes. Likewise, ocean-surface dissolved inorganic carbon concentrations can be tuned slightly to yield air-sea exchange fluxes that conform exactly to the steady-state equation for atmospheric CO2.
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From page 202... ...
The solid and dashed curves correspond to the fossil-fuel consumption scenarios shown in Figure 12.9. turns to a positive value representing the noncarbonate sedimentation rate.
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From page 203... ...
The solid and dashed curves correspond to the fossil-fuel consumption scenarios shown in Figure 12.9. Over a time scale of 10,000 yr (Figure 12.13)
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From page 204... ...
The model is likewise insensitive to large variations in the shape of the CO2 production curve for a given total integral under the curve. Calcite dissolution rate parameters also have little influence on the model results beyond a few thousand years.
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From page 205... ...
(19831. The West Antarctic ice sheet: Diagnosis and prognosis, in Proceedings of the Carbon Dioxide Research Conference, Carbon Dioxide, Science and Consensus, U.S.
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From page 206... ...
An improved geochemical model of atmospheric CO2 fluctuations over the past 100 million years, in The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present, E
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From page 207... ...
Minster (1982~. Methods for box models and ocean circulation tracers: Mathematical programing and nonlinear inverse theory, J
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