Antarctic Ice Sheet elevation impacts on water isotope records during the Last Interglacial

• Published in: Geophysical Research Letters
• Main Authors: Goursaud, Sentia, Holloway, Max, Sime, Louise, Wolff, Eric, Valdes, Paul, Steig, Eric J., Pauling, Andrew
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley for AGU 2020
• Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems; Antarctic; Talos Dome; The Antarctic; Antarc*; Antarctica; ice core; Ice Sheet; Sea ice
• Online Access: http://eprints.esc.cam.ac.uk/6022/; http://eprints.esc.cam.ac.uk/6022/1/finalsub.pdf; http://eprints.esc.cam.ac.uk/6022/2/finalsupp.pdf; https://doi.org/10.1029/2020GL091412

Plain Language Summary The Last Interglacial period (LIG, 116,000 to 130,000 years ago) was globally ∼ 0.8 °C warmer than today at its peak, with substantially more warming at the poles. It is a valuable analogue for future global temperature rise, especially for understanding rates and sources of polar ice melt and subsequent global sea level rise. Records of water stable isotopes from Antarctic ice cores have been crucial for understanding past polar temperature during the LIG. However we currently lack a framework for estimating how changes in the ice sheet elevation, alongside sea‐ice feedbacks, affect these water stable isotopes. To address this, we examine the effect of the Antarctic Ice Sheet (AIS) elevation on water stable isotopes, using an ensemble of climate simulations where we vary the AIS elevation. We observe that (i) water stable isotope values lower with increasing AIS elevation following linear relationships, (ii) the effect of sea‐ice induced by AIS elevation is small so the effect of AIS elevation can be isolated. Finally, this study provides appropriate elevation‐water stable isotope gradients for the reconstruction of the AIS topography using ice cores. Abstract Changes of the topography of the Antarctic ice sheet (AIS) can complicate the interpretation of ice core water stable isotope measurements in terms of temperature. Here, we use a set of idealised AIS elevation change scenarios to investigate this for the warm Last Interglacial (LIG). We show that LIG δ 18 O against elevation relationships are not uniform across Antarctica, and that the LIG response to elevation is lower than the preindustrial response. The effect of LIG elevation‐induced sea ice changes on δ 18 O is small, allowing us to isolate the effect of elevation change alone. Our results help to define the effect of AIS changes on the LIG δ 18 O signals, and should be invaluable to those seeking to use AIS ice core measurements for these purposes. Especially, our simulations strengthen the conclusion that ice core measurements from the Talos Dome core exclude the loss of the Wilkes Basin at around 128 ky.