Abstract. Oxygen and hydrogen isotope ratios in polar precipitation are widely used as proxies for local temperature. Used in combination, oxygen and hydrogen isotope ratios also provide information on sea surface temperature at the oceanic moisture source locations where polar precipitation originates. Temperature reconstructions obtained from ice core records generally rely on linear approximations of the relationships among local temperature, source temperature and water-isotope values. However, there are important nonlinearities that significantly affect such reconstructions, particularly for source-region temperatures. Here, we describe a temperature reconstruction method that accounts for these nonlinearities. We provide new reconstructions of absolute surface temperature, condensation temperature, and source-region evaporation temperature for all long Antarctic ice-core records for which the necessary data are available. We also provide thorough uncertainty estimates on all temperature histories. Our reconstructions constrain the pattern and magnitude of polar amplification in the past and reveal asymmetries in the temperature histories of East and West Antarctica. CP - Peer review - Improving temperature reconstructions from ice-core water-isotope records Articles | Volume 18, issue 6 Article Assets Peer review Metrics Related articles Articles | Volume 18, issue 6 https://doi.org/10.5194/cp-18-1321-2022 © Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License. https://doi.org/10.5194/cp-18-1321-2022 © Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License. Articles | Volume 18, issue 6 Article Assets Peer review Metrics Related articles Research article | 21 Jun 2022 Research article | | 21 Jun 2022 Improving temperature reconstructions from ice-core water-isotope records Bradley R. Markle and Eric J. Steig Bradley R. Markle CORRESPONDING AUTHOR bradley.markle@colorado.edu https://orcid.org/0000-0002-2282-6546 × Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA Department of Geological Sciences, University of Colorado, Boulder, CO, USA Department of Earth and Space Sciences, University of Washington, Seattle, WA, USA Eric J. Citation : https://doi.org/ 10.5194/cp-2021-37-AC1 RC1 : 'Comment on cp-2021-37' , Anonymous Referee #1, 13 Jul 2021 Markle and Steig are presenting quantitative temperature reconstructions obtained from Antarctic ice cores using an improved methodologies which considers the non-linearities in the water isotope/temperature relationships both at the sites (surface and condensation temperatures) and in the precipitation moisture source regions (SST and initial evaporation temperatures). However, I would suggest moving at least 1 or 2 figures from the appendix into the main text, in particular those reporting the differences between previous temperature reconstructions and the one reported in the present study (figure A 27) and the one reporting the main moisture sources for the different ice core sites (A24 or A8). 
 - The figures: sometimes I found difficult to understand the different colours and, in some cases, for examples for EPICA Dome C the same colour is used for different reconstructions, as in the case of Stenni et al. 2010 and Uemura et al. 2012. Moreover, in some case it is not possible to understand the different ice core records. 
 - Regarding the discussion about past elevation changes in West Antarctica from LGM and the Holocene: I would also refer to the Werner et al. (2018 Nature Comm) paper regarding this. Regarding the EDML reconstruction, are the upstream effects considered? 
 Detailed comments: 
 Page 10, Figure 5: It would be important to have a legend for the different ice core records. Moreover, some colours are very difficult to see. One record, but I do not know which is (the blue one…) has more positive dxs values at 20 kyr … which is strange… 
 Page 13, lines 14-19: I do not understand the difference between the absolute and relative uncertainties. Please, may you explain better? 
 Minor and technical comments: 
 Page 1, line 16: Change “Barbante et al.” in “EPICA Community Members”; change also in the References. 
 Page 1, line 19: add “*10 3 ”; 
 Page 14, line 7: add “of” between “function” and “reconstructed”. 
 Page 15, figure 8: the grey lines are not visible, and the same for light grey and thin dark grey …. 
 Page 16: figure 9: it is not possible to see in a clear way, moreover no way to understand to which ice core records you are referring. 
 Page 18, lines 8-10: I would suggest to add here something more about elevation changes ….. see paper from Werner et al 2018. Please check also EDML for upstream corrections. 
 Page 63, lines7-9 and also page 64 lines 1-2: there are two sentences that are repeated. Citation : https://doi.org/ 10.5194/cp-2021-37-RC1 AC2 : 'Reply on RC1' , Bradley Markle, 12 Apr 2022 Thank you very much for this helpful and thurough comment. Please see seperate uploaded response file. Citation : https://doi.org/ 10.5194/cp-2021-37-AC2 RC2 : 'Comment on cp-2021-37' , Anonymous Referee #2, 06 Sep 2021 General comments: This manuscript describes the improved method for reconstructing Antarctic temperature based on ice core water isotope record. Although the manuscript is very long (70 pages), it is organized well and easy to read. Maybe this is beyond the scope of this paper. I would like to ask about some comments about the differences between this and Buizert et al. (2021) (actually, the second author of this manuscript is a coauthor of Buizert et al. 2021). Buizert et al. (2021) Antarctic surface temperature and elevation during the Last Glacial Maximum, Science, 10.1126/science.abd2897 Specific comments Figure 5 left panels > I don not see each profile corresponds to which ice core. Please add appropriate legends in

<p>Ice cores represent one of the most important palaeoclimate archives, which record, among many other parameters, changes in stable oxygen and hydrogen isotopic composition and soluble ionic impurities. While impurities serve, for example, as proxies for sea ice, marine biological activity and volcanism, records of isotopic composition are the major proxy for the reconstruction of natural polar temperature variability. The latter is based on the temperature-dependent distillation and fractionation of the isotopic composition of water vapour along its atmospheric pathway and empirically determined relationships thereof.</p><p>However, temperature is by far not the only driver of isotopic composition changes. A single isotopic ice-core record will comprise variations caused by a multitude of processes, from variable atmospheric circulation and moisture pathways to the intermittency of precipitation and finally to the mixing and re-location of surface snow by wind drift (stratigraphic noise). Taken together, these additional processes constitute a large amount of noise in the single isotope record, which masks the true temperature-related variability. Averaging a sufficient number of records to reduce overall noise is one means to allow for quantitative reconstructions, but its effectiveness depends on the spatial scales of the involved processes. Here, we discuss an alternative approach. Assuming that major impurity species exhibit a seasonal cycle and are mainly also, along with the isotopic composition, deposited by precipitation and redistributed by wind, a large portion of their interannual variability should be linked, which would offer the possibility of using the impurities to correct the variability of the isotopic records.</p><p>In this contribution, we present the "ideal" dataset for testing this idea. We sampled and analysed isotopic composition and major impurity spec CO Meeting Organizer EGU2020 1){window.history.go(-1);}return false;">[Back] [Session CL1.14] EGU2020-15866, updated on 12 Jun 2020 https://doi.org/10.5194/egusphere-egu2020-15866 EGU General Assembly 2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Testing the ideal ice-core record for past temperature reconstructions using combined isotope and impurity analyses Thomas Münch 1 , Maria Hörhold 2 , Johannes Freitag 2 , Melanie Behrens 2 , and Thomas Laepple Thomas Münch et al. Thomas Münch 1 , Maria Hörhold 2 , Johannes Freitag 2 , Melanie Behrens 2 , and Thomas Laepple 1 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Research Unit Potsdam, Polar Terrestrial Environmental Systems, Potsdam, Germany 2 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Glaciology, Bremerhaven, Germany 1 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Research Unit Potsdam, Polar Terrestrial Environmental Systems, Potsdam, Germany 2 Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Glaciology, Bremerhaven, Germany Hide Ice cores represent one of the most important palaeoclimate archives, which record, among many other parameters, changes in stable oxygen and hydrogen isotopic composition and soluble ionic impurities. While impurities serve, for example, as proxies for sea ice, marine biological activity and volcanism, records of isotopic composition are the major proxy for the reconstruction of natural polar temperature variability. The latter is based on the temperature-dependent distillation and fractionation of the isotopic composition of water vapour along its atmospheric pathway and empirically determined relationships thereof. However, temperature is by far not the only driver of isotopic composition changes. A single isotopic ice-core record will comprise variations caused by a multitude of processes, from variable atmospheric circulation and moisture pathways to the intermittency of precipitation and finally to the mixing and re-location of surface snow by wind drift (stratigraphic noise). Taken together, these additional processes constitute a large amount of noise in the single isotope record, which masks the true temperature-related variability. Averaging a sufficient number of records to reduce overall noise is one means to allow for quantitative reconstructions, but its effectiveness depends on the spatial scales of the involved processes. Here, we discuss an alternative approach. Assuming that major impurity species exhibit a seasonal cycle and are mainly also, along with the isotopic composition, deposited by precipitation and redistributed by wind, a large portion of their interannual variability should be linked, which would offer the possibility of using the impurities to correct the variability of the isotopic records. In this contribution, we present the "ideal" dataset for testing this idea. We sampled and analysed isotopic composition and major impurity species on a four metre deep and 50 metre long trench at Kohnen Station, East Antarctica. This enables us to study the two-dimensional structure and relationship of both proxies to learn about their deposition mechanisms, their seasonality, and to test the ability of a combined isotope–impurity approach to reconstruct local temperatures by comparing so obtained temperature reconstructions with the local weather station data. How to cite: Münch, T., Hörhold, M., Freitag, J., Behrens, M., and Laepple, T.: Testing the ideal ice-core record for past temperature reconstructions using combined isotope and impurity analyses, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15866, https://doi.org/10.5194/egusphere-egu2020-15866, 2020 Share Displays Display file Close