The past 5000 years history of solar modulation of cosmic radiation from 10Be and 14C studies

• Published in: Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences
• Main Authors: Oeschger, H., Beer, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Royal Society of London 1990
• Subjects: 530 Physics; Byrd; Byrd Station; Antarc*; Antarctica; ice core
• Online Access: https://boris.unibe.ch/158605/1/rsta.1990.0028.pdf; https://boris.unibe.ch/158605/

10Be is produced in a similar way as 14C by the interaction of cosmic radiation with the nuclei in the atmosphere. Assuming that the 10Be and 14C variation are proportional and considering the different behaviour in the Earth system, the 10Be concentrations in ice cores can be compared with the 14C variations in tree rings. A high correlation is found for the short-term variations (14C-Suess-wiggles). They reflect with a high probability production rate variations. More problematic is the interpretation of the long-term trends of 14C and 10Be. Several explanations are discussed. The reconstructed CO2 concentrations in ice cores indicate a rather constant value (280 ± 10 p.p.m. by volume) during the past few millenia. Measurements on the ice core from Byrd Station, Antarctica, during the period 9000 to 6000 years BP indicate a decrease that might be explained by the extraction of CO2 from the atmosphere-ocean system to build the terrestrial biomass pool during the climatic optimum.