Geoarchaeology. 2020;1–16. wileyonlinelibrary.com/journal/gea © 2020 Wiley Periodicals LLC | 1 Received: 12 November 2019 | Revised: 23 March 2020 | Accepted: 19 June 2020 DOI: 10.1002/gea.21812 RESEARCH ARTICLE Mid‐Holocene environmental change and human occupation at Sai Island, Northern Sudan Katherine A. Adelsberger 1 | Jonathan Lewis 2,3 | Justin P. Dodd 4 | Danika Hill 1 | Jennifer R. Smith 2 | Elena A. A. Garcea 5 1 Department of Environmental Studies, Knox College, Galesburg, Illinois 2 Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri 3 Department of Earth Sciences, Arbeitsbereich Geochemie, Freie Universität Berlin, Berlin, Germany 4 Department of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 5 Dipartimento di Lettere e Filosofia, Università di Cassino e del Lazio Meridionale, Cassino, Italy Correspondence Katherine A. Adelsberger, Department of Environmental Studies, Knox College, 2 East South St., Galesburg, IL 61401. Email: kadelsbe@knox.edu Funding information National Geographic Society Committee for Research and Exploration, Grant/Award Number: grant # 9201‐12 Scientific editing by Jane Humphris. Abstract Holocene environmental change in the northern and central Nile Valley was con- trolled primarily by shifts in the Intertropical Convergence Zone over time, leading to changes in aridity and water availability for early occupants of the region. Although local environmental changes may help to motivate societal changes such as those in settlement patterns or technological productions, evidence from pedogenic carbonates at Sai Island, in northern Sudan, indicate that the most significant en- vironmental changes predated a key shift in local food production from foraging to pastoralism. Changes in local environmental conditions from a wetter and more diverse vegetative context to a more arid and C 4 ‐dominant landscape occurred during the occupation of Khartoum Variant foragers, whereas later Abkan pastor- alists arrived without any notable differences in the region compared to the en- vironments inhabited by the most recent foragers. The lack of an external environmental driver for food production changes at Sai suggests that other, po- tentially cultural factors were more important in these economic decisions in the mid‐Holocene. KEYWORDS environmental change, Nile Valley, pastoralism, pedogenic carbonate, stable isotopes, Sudan 1 | INTRODUCTION Although the current climate of northern Sudan is hyperarid (Kuper & Kroepelin, 2006), the region has experienced wetter cli- mates in the geologically recent past. During the Holocene climate optimum, ca. 9000‐ 6000 cal BP, North Africa experienced sig- nificant changes in regional climate and environment, including in- creases in precipitation and surface water availability due to northward movement of the Intertropical Convergence Zone (ITCZ; Abell & Hoelzmann, 2000; Abell, Hoelzmann, & Pachur, 1996; Bubenzer & Riemer, 2007; Hoelzmann, Kruse, & Rottinger, 2000; Hoelzmann, Schwalb, Roberts, Cooper, & Burgess, 2010; Kropelin et al., 2008; Nicoll, 2004; Pachur & Hoelzmann, 2000; Rodrigues, Abell, & Kröpelin, 2000). These changes caused an increase in Nile discharge (Paulissen & Vermeersch, 1987) as well as the presence of Sahelian vegetation in northern areas that are currently too arid to support such vegetative communities (Neumann, 1989). Follow- ing this mid‐Holocene optimum, however, water availability de- creased as more arid conditions gradually became established, with aridification intensifying most significantly after approximately 4500 BP (Abell & Hoelzmann, 2000; Krom, Stanley, Cliff, & Woodward, 2002; Nicoll, 2004; Williams et al., 2010; Woodward et al., 2015). Mid‐Holocene climatic shifts and associated changes in human water access correlate with important developments in human subsistence strategies and material culture, including the development of food production in the Nile Valley (Garcea & Hildebrand, 2009; Kuper & Kroepelin, 2006; Nicoll, 2001, 2004). However, potential causation between climate change and human cultural changes are less definitive and should be assessed in- dividually for each archaeological context.