Sectian 3.7: Lang Term Climate Changes
51
atmospheric eddy heat flux could generate a climate variability consistent
with the observed spectra over periods of 10 2 to perhaps as much as 10 4
years (Lemke, 1977; Robock, 1978), but the models were very simple and
the results have been much debated and refined. The effect of stochastic
fluctuations on the periodic forcing at the orbital frequencies has also been
studied (e.g., Sutera, 1981; Saltzman and Maasch, 1991) but, as models with
and without stochastic perturbations may show the same level of agreement
with the limited observations that are available, the importance of stochastic
forcing remains to be assessed.