Last Interglacial (MIS 5e) and Holocene sea surface temperature and environmental reconstructions from Yorke Peninsula, southern Australia

This study reconstructs sea surface temperatures (SSTs) and coastal environmental conditions during the Last Interglacial (MIS 5e) and the Holocene using δ 18 O and δ 13 C values of fossil marine molluscs from Yorke Peninsula, southern Australia. A total of 148 MIS 5e and 53 Holocene specimens were analysed. MIS 5e SSTs ranged from 17.6 ± 0.8 °C to 22.9 ± 0.9 °C, whereas the Holocene SSTs ranged from 15.7 ± 0.9 °C to 23.0 ± 1.6 °C. Paired comparisons between co-occurring species indicate that SSTs during MIS 5e were broadly comparable to those of the Holocene, with both periods exhibiting temperatures up to 4 °C higher than modern values at their warmest. In contrast, δ 13 C values for MIS 5e are consistently lower than those of the Holocene, consistent with increased freshwater input and wetter regional conditions. These results provide the first geochemical evidence for comparable SSTs but increased precipitation and runoff along the southern Australian coast during MIS 5e, offering rare quantitative constraints on how coastal environments in this region responded to interglacial conditions. • Amino acid racemization effectively distinguishes MIS 5e and Holocene fossils. • MIS 5e and Holocene SSTs were broadly comparable in southern Australia. • MIS 5e and Holocene SSTs up to 4 °C higher than modern at their warmest. • MIS 5e is associated with wetter conditions and enhanced coastal runoff.