Verena Foerster

In an era of increasing dis- and misinformation, particularly in relation to social and natural crises like climate change, it is vital that geography students can decipher legitimate, high-quality scientific data from falsehoods to solve relevant problems. In students’ education, geography teachers have a central role. We conducted an empirical study on German university geography education Bachelor students to better understand their scientific data awareness – their general understanding of what scientific data are, where they come from, and how to discern data quality – to determine how best we can support them in gaining (and ultimately teaching) skills to critically evaluate data. In their responses to an online survey, participants recognized their data usage within scientific and academic settings, but their perception of scientific geographic data in their daily lives was limited. Many respondents also displayed an inability to clearly articulate exactly how they would evaluate and verify data presented to them. Some individuals also indicated a strong inherent trust in scientific data – associating scientific data with “truth” and “fact”. We provide recommendations on how to teach geography students to use scientific data and enhance scientific data awareness, but ultimately demonstrate a need for further studies. This work can benefit the creation of new educational modules that can teach students 1) that scientific geographical data are everywhere in our daily lives and 2) how they can critically determine data quality and analyze data found online and through generative artificial intelligence.

Chew Bahir, a lake that is dry for most of the year, located in a tectonic basin in the southern Ethiopian Rift, was the target of several scientific drilling expeditions between 2009 and 2014. The aim of these expeditions was to explore the basin and its lake sediments as an archive of past changes in the environmental conditions during the evolution of our species, Homo sapiens. In more than 25 publications, the scientific findings derived from the analysis of the sediments were presented and discussed in detail. In the present paper, we provide the background information on the project's origins, planning and implementation – that is, information that has not yet been presented in scientific papers, or only very briefly, but which could be important for those working on similar projects in the future. Herein, we particularly focus on the advantages and disadvantages of obtaining twin cores at a short distance, aiming at a continuous high-quality composite core, a strategy that had to be defended during the planning stage of the project due to the higher costs involved but which is considered to be the best practice for scientific drilling in modern sedimentary basins.

The role that climate played in human evolution has been controversially discussed among scientists for decades. Inspired by these discussions, the Hominin Sites Paleolakes Drilling Project (HSPDP) conducted five deep drilling campaigns adjacent to key hominin fossil sites in eastern Africa, including the Chew Bahir Basin in southern Ethiopia. Analysis of the Chew Bahir lacustrine sedimentary record revealed that over the past 620,000 years, phases of environmental stability and instability occurred contemporaneously with milestones in human history, including pulsed dispersal events out of Africa coinciding with potential humid periods. Although proxies from Chew Bahir sediments have provided important qualitative information about relative changes in environmental conditions, we still lack quantitative information on water availability and an understanding of the dominant climatic forcings controlling water balance. Here we present the first radiogenic strontium isotope (87Sr/86Sr) record covering the past 50,000 years from four Chew Bahir sediment short cores (CB01, CB03, CB05, CB06) and one long core HSPDP-CHB-1A in a resolution of 100 to 1000 years measured on fish bones, endogenic calcites, and ostracods. We interpret the Sr isotope proxy to reflect water provenance changes, particularly controlled by the varying contribution of water overflowing from a series of lakes further north in Ethiopia. Our new Sr-isotope record shows a remarkable correlation with global sea level variability and does not show a pattern of precession paced cycles. Superimposed on this pattern, we see concurrent excursions in the Sr-isotope record of centennial- to millennial scale events such as Heinrich Event 1 (H1) or the Younger Dryas (YD). As Chew Bahir dominantly receives Indian Ocean moisture, the most likely driver of moisture availability in this part of eastern Africa is the temperature of western Indian Ocean surface water that varies in pace with glacial-interglacial climate change. Also on shorter time scales, reduced Indian Ocean surface temperatures correspond to reduced moisture in the tropical rainbelt resulting in dry conditions around H1 and the YD. Where other paleohydrological proxy data from lake fossils can be comparatively noisy because of the high spatial and seasonal variability in such tropical systems, the relatively conservative hydrochemistry of the Sr isotope signal in lakes like Chew Bahir makes this proxy relatively insensitive to seasonal variability while it faithfully captures decadal to longer time scale signals.

The time between 1,200 kyr BP and today includes the Mid-Pleistocene Transition, the Mid-Bruhnes Event, and the late Pleistocene. The Early-Mid Pleistocene Transition (~920 kyrs BP) is one of the most dramatic shifts in high-latitude climate and marked by the onset of the strong 100 kyr glacial-interglacial cycles. The Mid-Bruhnes Event marks a significant increase in the amplitude of the glacial-interglacial cycles. It has been identified mostly in marine sediments and Antarctic ice cores, but it is currently discussed whether it was a globally synchronous phenomenon, including the African continent. Marine records suggest a shift towards increased aridity in parts of Africa, and terrestrial records from eastern Africa indicate a generally wet climate, possibly with a transition from stable to unstable, as suggested by the Olorgesailie record. At this time, robust Australopithecines went extinct, and only the genus Homo survived as H. ergaster, which ultimately led to the emergence of our own species, H. sapiens. The time vector also includes the second major expansion wave of H. ergaster out of Africa (1.39–0.9 Ma, after the first wave at ~1.9–1.4 Ma), possibly through the Sinai land bridge, but expansions through the Gibraltar strait and via the Bab el- Mandeb strait and into the southern Arabian Peninsula are also subject to lively discussed.Here, we present the first insights into a comprehensive linear and non-linear analysis of five prominent records, which are (1) the dust record from ODP site 659 from western Africa, (2) the dust record from the Arabian Sea from ODP site 721/722, (3) the river runoff record from MD96-2048, (4) the combined dust and river runoff wetness index from ODP site 967, and (5) the south-western European ICDP record from Lake Ohrid. We use correlation metrics, such as the windowed Spearman correlation coefficient, to test for spatiotemporal synchronicity, asynchronicity, and possible interferences with the hominin fossil record. Furthermore, we use non-linear analysis, such as recurrence plots and recurrence quantification analysis, to test whether prominent climate transitions or spatiotemporal shifts in the fossil record are in temporal alignment with recurrence-based insights.

Why does drilling into a dried-out lake in eastern Africa get scientists excited? Simple answer: the lake’s sediments store valuable information about how past climate change shaped the environment where our earliest ancestors lived. Those sediments serve as a natural record of Earth’s ancient climate. While much is known about human evolution from fossil discoveries in eastern Africa, the role that climate change might have played for human biological and cultural evolution remained unclear for a long time. But now we have drilled 278 m into the ground at the bottom of the old Chew Bahir Lake in southern Ethiopia, which has given us some detailed answers. This natural record covers the last 620,000 years of climate history from one of the proven habitats of ancient Homo sapiens, and it can help us to unravel connections between climate and human evolution.

Scientific drill cores provide unique windows into the processes of the past and present. In the dynamic tectonic, environmental, climatic, and ecological setting that is eastern Africa, records recovered through scientific drilling enable us to look at change through time in unprecedented ways. Cores from the East African Rift System can provide valuable information about the context in which hominins have evolved in one of the key regions of hominin evolution over the past 4 Myr. The Deep Drilling in the Turkana Basin (DDTB) project seeks to explore the impact of several types of evolution (tectonic, climatic, biological) on ecosystems and environments. This includes addressing questions regarding the region's complex and interrelated rifting and magmatic history, as well as understanding processes of sedimentation and associated hydrothermal systems within the East African Rift System. We seek to determine the relative impacts of tectonic and climatic evolution on eastern African ecosystems. We ask the follow questions: what role (if any) did climate change play in the evolution of hominins? How can our understanding of past environmental change guide our planning for a future shaped by anthropogenic climate change? To organize the scientific community's goals for deep coring in the Turkana Basin, we hosted a 4 d ICDP supported workshop in Nairobi, Kenya, in July 2022. The team focused on how a 4 Myr sedimentary core from the Turkana Basin will uniquely address key scientific research objectives related to basin evolution, paleoclimate, paleoenvironment, and modern resources. Participants also discussed how DDTB could collaborate with community partners in the Turkana Basin, particularly around the themes of access to water and education. The team concluded that collecting the proposed Pliocene to modern record is best accomplished through a two-phase drilling project with a land-based transect of four cores spanning the interval from 4 Ma to the Middle–Late Pleistocene (< 0.7 Ma) and a lake-based core targeting the interval from ∼ 1 Ma to present. The second phase, while logistically more challenging due to the lack of drilling infrastructure currently on Lake Turkana, would revolutionize our understanding of a significant interval in the evolution and migration of Homo sapiens for a time period not currently accessible from the Kenyan part of the Turkana Basin. Collectively, the DDTB project will provide exceptional tectonic and climatic data directly associated with one of the world's richest hominin fossil localities.

The transition from a humid green Sahara to today’s hyperarid conditions in northern Africa ~5.5 thousand years ago shows the dramatic environmental change to which human societies were exposed and had to adapt to. In this work, we show that in the 620,000-year environmental record from the Chew Bahir basin in the southern Ethiopian Rift, with its decadal resolution, this one thousand year long transition is particularly well documented, along with 20–80 year long droughts, recurring every ~160 years, as possible early warnings. Together with events of extreme wetness at the end of the transition, these droughts form a pronounced climate “flickering”, which can be simulated in climate models and is also present in earlier climate transitions in the Chew Bahir environmental record, indicating that transitions with flickering are characteristic of this region.

As a contribution towards a regional environmental context of human-climate interactions, the ICDP co-funded Chew Bahir Drilling Project, a part of the HSPDP (Hominin Sites and Paleolakes Drilling Project), recovered ~280-m long cores of sedimentary strata through continental scientific drilling in southern Ethiopia. The fluvio-lacustrine coring locality in the Chew Bahir basin is situated near key archaeological and paleoanthropological sites, such as the Omo-Kibish where the Omo 1 and 2 Homo sapiens fossils were recovered.Here we present the 620,000-year environmental record from Chew Bahir that provides an extraordinary opportunity to examine the potential influence of climate variability on hominin evolution, cultural innovation and dispersal during the Middle to Late Pleistocene. The near-continuous Chew Bahir record documents 13 environmental episodes that differ in length and character, potentially inducing habitat changes influencing hominin biological and cultural transformation. We infer that long-lasting and relatively stable humid conditions from ~620,000–275,000 years BP (Episodes 1–6) were interrupted by several abrupt and extreme hydroclimatic oscillations. This phase coincided with the appearance of high anatomical diversity in hominin groups. During Episodes 7–9 (~275,000–60,000 years BP), a pronounced pattern of climatic cyclicity was paralleled by the gradual transition from Acheulean to Middle Stone Age technologies, the emergence of H. sapiens in eastern Africa, and a key phase of human social and cultural innovation. Episodes 10–12 (~60,000–10,000 years BP), marked by high-frequency climate oscillations, is contemporaneous with the global dispersal of H. sapiens, facilitated by continued technological innovation and the alignment of humid pulses between eastern Africa and the eastern Mediterranean.Prospectively, the Chew Bahir record represents a crucial component for the Middle and Late Pleistocene in the ongoing efforts of the scientific community (future and upcoming ICDP-funded projects) to address questions in Africa across four topical core areas: paleoclimate, paleoenvironment, basin evolution, and modern lake systems.

The study of the mid-Holocene climate tipping point in tropical and subtropical Africa is the subject of current research, not only because there is a comparatively simple but nonlinear relationship between the change in cause (orbital forcing) and the accelerated response of the monsoon system, but also because the African monsoon is an example of a potentially positive evolution of living conditions for humans: modeling results suggest that the Sahel is expanding northward in the wake of human-induced recent global warming, with green belts spreading northward. New literature distinguishes tipping elements such as the African monsoon according to the nature of the cause and the response of the climate system. Research here focuses primarily on tipping points of the type, which is characterized by a critical slowing down and a decreasing recovery from perturbations. The African monsoon, on the other hand, is an example of the tipping point of the type, which is characterized by flickering before the transition. The two types also differ in the nature of their early warning signals (EWS). These EWS are increasingly becoming the focus of research, as they are particularly important for predicting possible tipping of climate in the future of our planet. For the African monsoon system, flickering between two stable states near the transition has been predicted by modeling, but has not yet been demonstrated on paleoclimate time series.The paleoenvironmental record from the Chew Bahir Basin in the southern Ethiopian Rift, which documents the climate history of eastern Africa of the past ~620 ka with decadal resolution in some parts provides the possibility to examine the termination of the African Humid Period (AHP, ~15–5 kyr BP) with regard to the possible occurrence of EWS. Thanks to six well-dated short sediment cores (<17 m, <47 kyr BP) and two long cores (~290 m, <620 ka BP) we can not only study the last climate transition at ~5.5 kyr BP in detail, but also similar transitions including possible EWS long before the first occurrence of Homo sapiens at ~318 ka BP on the African continent. The analysis of the Chew Bahir record reveals a rapid (~880 yr) change of climate at ~5.5 kyr BP in response to a relatively modest change in orbital forcing that appears to be typical of climate tipping points. If this is the case then 14 dry events at the end of the AHP and 7 wet events after the transition, each of them 20–80 yrs long and recurring every 160±40 yrs, could indeed indicate a pronounced flickering between wet and dry conditions at the end of the AHP, providing significant EWS of an imminent tipping point. Compared to the low-frequency cyclicity of climate variability before and after the termination of the AHP, the flickering occurs on time scales equivalent to a few human generations and it is very likely (albeit speculative) that people were conscious of these changes and adapted their lifestyles to the rapid changes in water and food availability.

The eastern branch of the East African Rift System hosts many shallow modern lakes and paleolakes, which can be sensitive recorders of changing climate conditions (complicated by tectonics) during the past few million years. However, many of such lakes are saline–alkaline (salty and high pH), and these conditions do not easily preserve pollen and other biologically derived paleoclimate indicators. Fortunately, some preserved minerals that formed in these extreme environments reflect subtle shifts in lake water chemistry (controlled by changes in climate conditions) and therefore provide a continuous record of local and regional climate change. We present two different mineral proxies (zeolites and clays) from two different paleolake basins (Olduvai Gorge, Tanzania, and Chew Bahir, Ethiopia) as examples.