A chironomid-based reconstruction of late Holocene climate change in southern Costa Rica
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The modern distribution of sub-fossil chironomids in Costa Rica is described making use of a fifty-four lake calibration set. The relationship between modern chironomid distribution and the measured limnological variables indicated that surface water temperature (SWT) accounts for a statistically significant amount of variance in the chironomid communities. A chironomid-based inference model for SWT, developed using weighted-averaging partial least squares, was applied to sub-fossil midge assemblages from Laguna Zoncho, Costa Rica, to reconstruct late Holocene thermal variability. The major findings of this study are: (1) SWT between1750 and 3100 cal yr BP was higher than the late Holocene average, (2) southern Costa Rica was characterized by below average temperatures during the Little Ice Age, and (3) Laguna Zoncho experienced very low lake levels, possibly reflecting drought, during the Medieval Climate Anomaly. This study pioneers the use of sub-fossil chironomid remains to develop quantitative estimates of Holocene thermal variability in Central America.