Chironomid-based palaeotemperature estimates for northeast Finland during Oxygen Isotope Stage 3

Abstract

Quantitative palaeotemperature estimates for the earlier part of Oxygen Isotope Stage (OIS-) 3 are inferred from subfossil chironomid remains. The high-latitudinal study site of Sokli, northeast Finland, provides for a unique lacustrine deposit covering the earlier part of OIS-3, and the chironomid remains found in the sediments show that a shallow lake with a diverse fauna was present at the study site throughout the record. Using a Norwegian calibration data set as a modern analogue, mean July air temperatures are reconstructed. The chironomidinferred July air temperatures are surprisingly high, reaching values similar to the current temperature at the study site. Other proxies that were applied to the sediments included the analysis of botanical and zoological macro-remains, and our results concur with temperature estimates derived from climate indicator taxa. Summer temperatures for interstadial conditions, reconstructed with climate models, are as high as our proxy-based palaeotemperatures.

How did Marine Isotope Stage 3 and Last Glacial Maximum climates differ? – Perspectives from equilibrium simulations

“…Vandenberghe (1992) did not find evidence for enhanced seasonality during MIS 3 in The Netherlands, with summer temperatures only a few degrees warmer than at LGM, while winter temperatures were much reduced, resulting in continuous permafrost. However, Coope (1997), and Engels et al (2007) point out that, during at least one MIS 3 interstadial, warm, close to present-day summer conditions prevailed over Central England (∼18 • C) and northeast Finland (∼13 • C). These warm summers in MIS 3 over mid-and high northern latitudes are consistent with our findings.…”

Stable oxygen isotopes in chironomid and cladoceran remains as indicators for lake‐water δ18O

“…Larval head capsules of chironomids preserve well for thousands to ten thousands of years in lake sediments (Heiri et al 2007;Engels et al 2008). Similarly, cladoceran remains can be found in large abundances in lake sediment records (Korhola and Rautio 2001).…”

Strengths and Weaknesses of Quantitative Climate Reconstructions Based on Late-Quaternary Biological Proxies

“…WA optima) are more likely to be poorly estimated and have large standard errors associated with them in cross-validation (Birks 1998). Bigler et al (2002), Heiri et al (2007) Engels et al (2008, and illustrate the use of these numerical evaluation criteria in studies on climate change using a range of proxies. These numerical criteria are, however, only a guide to the possible reliability of the reconstructions.…”

“…Within the vast literature about calibration data-sets, some papers critically identify and discuss in detail some of these potential errors (e.g. Birks et al 1990;Jones & Juggins 1995;Lotter et al 1997Lotter et al , 1998Engels et al 2001Engels et al , 2008Bigler et al 2002;Whitmore et al 2005;Finkelstein et al 2006;Heiri et al 2007;Gonzales et al 2009a;.…”