ResearchResearch Expedition: Climate and Cultural Change in the Aegean Sea

Press Release No. 117/2023
10 November 2023

Heidelberg Earth scientists lead research ship METEOR’s voyage to the eastern Mediterranean

How did climatic and environmental change impact early eastern Mediterranean cultures, and what were the consequences of human settlement on land and marine ecosystems? In order to collect research data to answer these questions, the German research ship METEOR – under the guidance of Earth scientists from Heidelberg University – is embarking on a multi-week expedition to the Aegean and Ionian seas. The international research team will collect sediment cores from the sea floor along the coast of Greece, which they will use to reconstruct the interplay of climatic, environmental, and cultural change during the past 11,500 years. The research team will also include Heidelberg archaeologists and geographers, in addition to cooperation partners from Greece, France, and the United States.

“Sediment cores from the sea floor can provide unique insights into climatic and environmental changes in the Mediterranean region throughout history. If they can be correlated timewise with archaeological finds on land, it will be possible to draw new conclusions about connections between climatic events and socioeconomic or sociocultural upheavals,” explains Prof. Dr Jörg Pross, a researcher at the Institute of Earth Sciences at Heidelberg University and the scientific leader of the expedition. The special thing about marine sediment cores acquired from coastal areas is that they allow a reconstruction of both the environmental conditions in the sea and also on the mainland near the coast. They contain a broad range of different climatic and environmental indicators deriving not only from the sea but also from land, such as pollen from terrestrial plants or molecular biomarkers that washed into the sea and accumulated on the sea floor.

One goal of the subsequent scientific investigations will be to reconstruct the impacts of short-term climatic and environmental changes on early human cultures in the Aegean region. For example, changed climatic conditions might have contributed to the end of the early Bronze Age in Greece around 4,200 years ago. Another topic to explore will be whether climate change impacted on the sociocultural change ensuing with the collapse of the Mycenaen civilisation in Greece and the Hittite empire in Asia Minor about 3,200 years ago. Importantly, the researchers also want to examine the cores to determine how the spread of human cultures over the past 11,500 years has influenced ecosystems on land and under water. 

The scientists have now evaluated the first cores drilled during a previous expedition to the Aegean in January 2018. The new data shows that humans were already making a considerable impact on the environment thousands of years ago. “Our analysis of the lead content and lead isotope ratios in the marine sediment cores enabled us, for example, to trace the strong increase in lead concentration visible in these cores back to the massive exploitation of the Laurion silver mines approximately 2,700 to 2,500 years ago. These mines made a major contribution to the wealth and advancement of Athens,” explains Prof. Pross. The forest cover in the hinterland declined significantly during the same period – an indication of the great demand for wood when extracting and smelting the ore, according to the Heidelberg palaeoclimatologist. 

The available data further suggest a profound change in the marine food chain. For example, around 6,000 years ago there were considerably more fish in the Aegean than today, and the fish populations were completely different in composition. Whether overfishing played a role besides climatic influences is a question the current expedition also aims to answer. “Sediment cores from areas near centres of early human civilisations, for instance in Crete or the Peloponnesian Peninsula, will − we hope − provide new findings on the sensitivity and resilience of early cultures to environmental change and the vulnerability of ecosystems through early human influence,” says Jörg Pross.

The expedition with the METEOR research ship is being funded by the Federal Ministry of Education and Research and the German Research Foundation.

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    The German research vessel METEOR
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    The gravity corer
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    The gravity corer on board the METEOR
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    The multicorer