Beryllium-10, produced by spallation of atmospheric nitrogen and oxygen by cosmic rays, is a key proxy for reconstructing past solar activity, cosmic-ray flux variations, extreme solar events, and geomagnetic field changes. Its content in natural archives—primarily ice cores, marine sediments, and terrestrial soils—offers a unique proxy for the long-term evolution of solar variability, geomagnetic changes, and Earth’s climate.
Despite its broad applications, the full use of ¹⁰Be as a quantitative solar proxy is challenging. While past studies have largely attributed ¹⁰Be variability to solar and geomagnetic activity, recent research has revealed the importance of atmospheric transport processes, stratospheric circulation changes, and large-scale climatic variations in its deposition. This can introduce uncertainties in both long-term reconstructions of solar cycles and the identification of extreme solar energetic particle (SEP) events, complicating efforts to disentangle solar signals from terrestrial effects. Without better constraints on these processes, estimates of past solar activity—particularly the frequency and intensity of extreme events—remain imprecise, limiting our ability to assess their potential risks in the modern era.
This ISSI team project brings together expertise from solar and space physics, atmospheric sciences, and isotope geochemistry to refine the interpretation of ¹⁰Be as a quantitative proxy for past solar variability. By merging high-resolution ¹⁰Be records with state-of-the-art atmospheric transport models, we aim to improve the accuracy of past solar reconstructions and better quantify transport- and climate-related uncertainties in ¹⁰Be deposition. A particular focus will be put on reassessing known extreme SEP events, such as those in 774 CE and 993 CE, and evaluating the potential for detecting previously unrecognized solar events in the paleorecord.
By improving the reliability of ¹⁰Be-based reconstructions, this project will enhance our understanding of both long-term solar variability and extreme solar events. The results will contribute to more accurate past space climate reconstructions, refined estimates of solar-driven climate variability, and improved assessments of future extreme event risks. This will strengthen interdisciplinary collaboration across solar and heliospheric physics, space physics, atmospheric sciences, and geochemistry, fostering a more comprehensive approach to studying the Sun-Earth system.