Human-climate-environment interactions and landscape transformation in Espiritu Santo, Vanuatu during the past millennium

Giorgia Camperio^1,2*S. Nemiah Ladd³Matiu Prebble^4,5Cindy De Jonge¹Tobias Schneider²Elena Argiriadis^6,7Ronald Lloren^1,2Daniel B Nelson³Amicie A. Delahaie^2,8Christiane Krentscher²Nathalie Dubois^1,2*

• ¹Department of Earth Sciences, ETH Zurich, Zurich, Zürich, Switzerland
• ²Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
• ³Department of Environmental Sciences, Faculty of Science, University of Basel, Basel, Switzerland
• ⁴University of Canterbury, Christchurch, Canterbury, New Zealand
• ⁵Department of Archaeology and Natural History, School of Culture, History and Language, College of Asia and the Pacific, Australian National University, Canberra, Australian Capital Territory, Australia
• ⁶Institute of Polar Sciences, Department of Earth System Sciences and Technologies for the Environment, National Research Council (CNR), Venezia, Emilia-Romagna, Italy
• ⁷Department of Environmental Sciences, Informatics and Statistics, Ca 'Foscari University of Venice, Venice, Veneto, Italy
• ⁸École Normale Supérieure, Paris, Ile-de-France, France

Over the past millennium, the tropical Pacific Islands of Remote Oceania have experienced significant transformations caused by different waves of human settlement and climatic variability. However, many sites remain to be explored for their archeological potential, and the complex climatic setting of the tropical Pacific further complicates our understanding of past environmental and societal changes. However, the paucity of archeological records coupled with the complex climatic setting of the tropical Pacific hinders our understanding of past environmental and societal changes. In this study, we applied a multi-proxy approach to sediment cores extracted from ponds on the west coast of Espiritu Santo, Vanuatu to investigate past human-climate dynamics. Through the analysis of human-associated proxies including fecal markers, palmitonea specific lipid biomarker for tarocrop pollen and sedimentary charcoal, we reconstructed changes in human presence and activities. We reconstructed past hydroclimate from leaf wax hydrogen isotopes (δ 2 HLW) and past temperatures from branched glycerol dialkyl glycerol tetraethers (brGDGTs). Changes in pollen revealed major shifts in local and regional vegetation. In our record, the period from 1000 to 1300 CE was characterized by warm/wet conditions concomitant with demographic expansion inland. Around 1400 CE, pollen, leaf wax distributions, and δ 2 HLW data indicated a drier period. The coincident decrease in palmitone, despite high charcoal and fecal marker concentrations, suggested that drier conditions might have rapidly restricted taro cultivation, but not the overall population, which declined more than a century later. We hypothesize that the establishment of one of the earliest European settlements in Oceania in 1606 CE further disrupted local demographics with the introduction of epidemic diseases. This study contributes to our understanding of the intricate relationship between human activities, climatic fluctuations, and landscape modifications in Remote Oceania over the past millennium.