Marine paleotemperature is a significant factor in the subsistence productivity of many coastal regions and may be an important factor in the evolution of maritime societies. A California paleotemperature model, spanning 8,000 calendar years, correlates periods of high sea surface temperatures with decreased marine subsistence productivity. A recent case study involving this model identified warming conditions between A.D. 1150 to 1300 as a major cause of subsistence distress for dwellers of the northern Channel Islands. These results are questionable, based on a comparison with data from other sites and periods of high sea temperature. Research at the Little Harbor site, one of the most extensively researched in the Channel Islands, shows that high sea temperature about 5,200 calendar years ago may have introduced warm-water faunas but not starvation conditions. Evidence from other sites occupied during subsequent warming cycles, including the event between A.D. 1150 to 1300, points to similar conclusions. Understanding the effects of long- and short-term ocean temperature cycles, a focus on only a small segment of the Holocene paleotemperature curve, and weak evidence that food abundance was affected by sea temperature are problems that must be overcome before the validity of the paleotemperature model can be accepted.
Black abalone (Haliotis cracherodii) population structure shifts through deep time: Management implications for southern California's northern Channel Islands