HISCAR

The radiocarbon method (¹⁴C) has significantly shaped scientific research for decades and revolutionised our understanding of the past. Today, this proven method is on the verge of a second revolution that has the potential to fundamentally change our perspective on the sun, climate and human history. The CEZA project HISCAR is funded by the research programme INTERNATIONALE SPITZENFORSCHUNG of the Baden-Württemberg Foundation and covers a period of three years, which began on 1 February 2024.

Originally used in archaeology, the radiocarbon method also conquered the environmental sciences in the 1960s, particularly for research into the carbon cycle. Now the method is making its way into solar research. A groundbreaking project focuses on the ¹⁴C method and extends its applications to three key areas: solar, climate and archaeological research.

The aim of the project is to use high-precision ¹⁴C analyses to reconstruct solar variability and changes in the carbon cycle in the past. The results will significantly expand our knowledge of the causes, timing and frequency of changes in solar activity and the Earth’s carbon cycle. The amount of radiocarbon produced in the atmosphere is directly related to solar activity, so an archive that stores ¹⁴C concentrations can be used to reconstruct solar behaviour in the past. Such archives also provide information on the carbon cycle, in particular on the exchange between the atmosphere and the oceans.

Hohenheim tree ring collection at CEZA of crucial importance

The most important archives for historical ¹⁴C values are trees that absorb atmospheric carbon directly via photosynthesis and store this carbon signal in the wood of their growth rings. In addition to the internationally renowned ¹⁴C laboratory, the Curt-Engelhorn Centre for Archaeometry also houses one of the world’s largest tree ring archives – the Hohenheim tree ring collection. The archive comprises wood from the last 13,000 years.

In collaboration with the ¹⁴C group at the University of Groningen, which specialises in the interpretation of ¹⁴C data from tree rings, both teams will take the history of the carbon cycle to a new level through tree-ring analyses.

This pioneering project will focus on two key periods over the next three years:

• The 1st millennium BC, a period of mass human migration possibly triggered by climate change.

• The early civilisation in the West and East from 2600-1700 BC, an era that includes the Early Bronze Age in the Mediterranean and the period of state formation in early China. In addition, the 4.2 ka climate event (~4,200 years before present) falls within this period, which is considered the strongest climatic event of the last 5,000 years.

By filling data gaps and creating long, uninterrupted datasets of high-resolution ¹⁴C data, this initiative could herald a second radiocarbon revolution, as this data is urgently needed in solar, climate and archaeological research to complete the overall picture.