It is interesting that the record of Ether should indicated a drought during the same basic time period that saw the abandonment of San Lorenzo. One of the known facets effective local populations was drought cycles. Webster notes the data for the later Maya, but there is every reason to believe that the effects of the similar climatic changes would have had a similar effect upon the Olmec, since their agricultural system was so similar:
“Sometimes plenty of rain falls, but it arrives a bit late, or there is an unusually dry interval as the crops ripen. In these circumstances, the harvest might be sparse, but people can generally tighten their belts and get by. More serious are marked deficiencies in annual rainfall extending over one or several years. Such protracted droughts can cause widespread famine, along with disease and social disruption. Many episodes of hunger, death, and conflict related to droughts of this kind are featured in the various Books of Chilam Balam, and scores of historical droughts are also recorded for northern Yucatan during Colonial and later times. Although exact census figures are unavailable, during the worst of them as many as 30-50 percent of the rural Maya population might have died.” (David Webster. The Fall of the Ancient Maya. Thames & Hudson, 2002, p. 239).
The effect of this particular drought on the Jaredites appears to have mirrored the suggestion of a 30-50 percent mortality rate. As the story of this drought continues, it stresses the desperation and the death. While there is no specific indication that the abandonment of San Lorenzo was related to a severe drought, it would be consonant with minor regional collapses in later history.