Reconstruction of past changes in salinity and climate using a diatom-based transfer function

Abstract

THE prospect of global warming has focused attention on the role of palaeoecology in testing the accuracy and sensitivity of climate-model predictions, in identifying past analogues for future climate change, and in placing model-predicted climate responses in the context of natural climate variability1,2. Proxy data for climate reconstruction can be derived from many sources, including the palaeolimnological record3,4. In closed-basin lakes in arid and semi-arid regions, shifts in effective moisture lead to the concentration or dilution of dissolved salts, and these changes in salinity are clearly reflected in the composition of lacustrine diatom assemblages5–8. Here we refine a previously published9 diatom-based transfer function for the reconstruction of past changes in salinity of lakes in the northern Great Plains region of North America, and apply the refined transfer function to a late-glacial and Holocene sediment record from Devils Lake, North Dakota. Our results show that there were a number of alternations between fresh and saline conditions during the Holocene and hence demonstrate the utility of the technique in reconstructing past changes in regional climate.