A paleoprecipitation and paleotemperature reconstruction of the Last Interglacial in the southeastern Alps
Abstract. The Last Interglacial (LIG, ~130–116 ka) was one of the warmest interglacials of the past 800,000 years and an important test bed for future climate conditions warmer than today. LIG temperature reconstructions from marine records as well as paleoclimate models show that mid and high northern latitudes were considerably warmer by about 2 to 5 °C compared to today. In Central Europe, the LIG has been widely studied using pollen and more recently chironomids preserved in lake sediments. While these bio-archives document temperatures changes across the LIG, they are commonly poorly constrained chronologically. Speleothems, and fluid inclusions contained therein, offer superior age control and provide information on past climate, including qualitative and partly also quantitative records of temperature and precipitation. Here, we present a precisely dated fluid inclusion record based on seven speleothems from two caves in the SE Alps (Obir and Katerloch) and use a δD/T transfer function to reconstruct regional LIG temperatures. We report a temperature change across the glacial/interglacial transition of 5.2 ± 3.1 °C, and peak temperatures at ~127 ka of 2.4 ± 2.8 °C above today’s mean (1973–2002). The fluid inclusion δD record of these speleothems exhibits millennial-scale events during the LIG that are not well expressed in the δ18Ocalcite. The early LIG in the SE Alps was marked by an important climate instability followed by progressively more stable conditions. Our record suggests that the SE Alps predominantly received Atlantic-derived moisture during the early and mid LIG, while more Mediterranean moisture reached the study site at the end of the LIG, buffering the speleothem δ18Ocalcite signal. The return towards colder conditions is marked by an increase in δ13C starting at ~118 ka indicating a decline of the vegetation and soil activity.
Charlotte Honiat et al.
Status: final response (author comments only)
RC1: 'Comment on cp-2022-78', Attila Demény, 20 Oct 2022
- AC1: 'Reply on RC1', Charlotte Honiat, 07 Mar 2023
RC2: 'Comment on cp-2022-78', Dominique Genty, 30 Dec 2022
- AC2: 'Reply on RC2', Charlotte Honiat, 07 Mar 2023
Charlotte Honiat et al.
Charlotte Honiat et al.
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The paper deals with stable C and O isotope compositions of speleothem calcite and H isotope compositions of inclusion-hosted water extracted from several speleothems that cover the last interglacial. Although the regional or hemispheric paleoclimate conditions, large-scale teleconnections and moisture transport processes are not dicussed in detail, the paper is a really fair study, clearly and concisely written, and gives a new view on the last interglacial’s conditions. As a conclusion, I suggest publishing the manuscript in Climate of the Past with minor revision.
Abstract and onwards
δD is an old term, the new IUPAC definion requires the use of δ2H instead. I suggest to correct it in the entire manuscript.
The expressions of „calcite stable isotope” and „fluid inclusion isotope” are a bit sloppy, the correct terms would be „stable isotope compositions of ...”. The short titles „oxygen isotopes” and „carbon isotopes” should also be corrected for more correct terms, like „Stable oxygen isotope compositions”. The reason is that although there is no radioactive oxygen isotope, this is not valid for carbon that has 14C.
Fig. 2: black arrows would be more visible.
Chapter 5.1.1., first sentence. The temperature of the cave would controll the oxygen isotope composition of the speleothem calcite, but would not affect the δ18O value of the drip water. I think these two are mixed in the sentence.
Chapter 5.1.1., last sentence. This is called Replication Test, and the paper of Dorale and Liu (2009 should be cited.
Dorale J.A. – Liu Z. 2009: Limitations of Hendy test criteria in judging the paleoclimatic suitability of speleothems and the need for replication. – J. Caves Karst Stud., 71, pp. 73–80.
Chapter 5.1.2. In order to determine if biogenic activity or kinetic fractionation is the main factor in the δ13C values, these two should be compared by numbers. We saw that along-lamina δ13C shifts can reach 4 ‰, which is not negligible. On the other hand, we see no information on the δ13C difference between winter and summer laminae.
Chapter 5.2.1., last paragraph. I think the paper of Demény et al. (2021) could be cited here.
Line 340. There is a sudden change from the δ18O/T gradients to the δ2H/T values. I think the δ2H/T values are calculated from the δ18O/T ones using the LMWL equation, but this should be clarified in a bit more detailed discussion.
Line 357. Actually the MIS6-MIS5 glacial-interglacial δ2H change can be observed in the ABA-1 and the BAR-II records together (see Fig. 6).