Predicting the Long Term Future of
S. H. Lam
Linear and nonlinear analyses are performed on a generic carbon cycle
model, exploiting available empirical information and avoiding detailed
physics as far as possible. It is shown that the ability to reproduce CO2
historical data of past decades is neither necessary nor sufficient to
establish credibility for the century-timescale predictions. This is because
the relevant CO2 historical data is driven by a ``rapid'' exponential forcing
term, while the future forcing term of interest is expected to be flat
and slowly time varying. Simple analytical formulas relating long term
atmospheric CO2 level and anthropogenic emission are derived, involving
only three parameters. In the century-timescale, there is no known quick
way to empirically determine or validate these parameters. An estimate
of the time to breach an user-specified threshold of atmospheric CO2 level
in terms of this parameter is provided.
Last updated April 1, 1998.
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