The Role of Climate Variability

Palaeoclimatic evidence suggests that short-term climate variability may have been substantially different from today during 

Liu et al. (1999b), in simulations examining the response of the Fast Ocean Atmosphere Model (FOAM Jacob, 1998) to 11,000 yr B.P. orbital forcing, have shown that El Nino variability is reduced by ca. 20% and the spectral bandwidth of El Nino changes from the broad (3-10 year) peak characteristic of the modern simulations to a narrower peak (2-3 year) at 11,000 yr B.P. This reduction in the variability appears to be associated with the simulated increase in the Indian summer monsoon. There are, however, a number of mechanisms through which changes in the Indian summer mon.soon circulation appear to impact the El NiiTo signal. First, the enhanced Indian monsoon 

Otto-Bliesner (1999) found that the teleconnections relating the patterns of Pacific ENSO to Sahelian rainfall in the 6000 yr B.P. experiment are different from those in the control (modern) simulation. We have therefore reexamined the FOAM simulations specifically to determine whether there are changes in precipita- 

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