Quantitative paleotemperature estimates from δ18O of chironomid head capsules preserved in arctic lake sediments

A paleoenvironmental perspective of temperature change is paramount to understanding the significance of recent warming in the Arctic. Late Quaternary sediments from many arctic lakes provide environmental archives with decadal resolution, but reconstructions are hampered by the relative insensitivity of many traditional proxies to temperature. Here, we show that the delta(18)O of head capsules of chironomid larvae are equilibrated with the delta(18)O of lakewaters in which they live. In suitable lakes, lakewater delta(18)O is controlled by the delta(18)O of local precipitation, which is strongly correlated to mean annual air temperature ( MAT). From this correlation, chironomid delta(18)O can be used to examine past changes in MAT. We illustrate the potential of this novel approach to paleothermometry with examples from two arctic lakes that reveal strong regional paleoclimatic gradients in the early Holocene.