A paper published today in Science uses radiocarbon (14C) data to show that existing climate models underestimate the amount of carbon dioxide (CO2) that is taken up by global vegetation, while overestimating the turnover time of carbon in the biosphere.
This research has been carried out by an international team led by Dr Heather Graven at Imperial College London. The IUP Heidelberg is represented among the authors by Ingeborg Levin, our pioneer in radiocarbon research who sadly died in February. The work demonstrates the usefulness of radiocarbon measurements in disentangling and quantifying complex processes in the carbon cycle on the global scale, very much in the spirit of earlier important contributions by Ingeborg Levin.
In the current study, a special period in the history of atmospheric radiocarbon concentrations was used in combination with model simulations to understand how plants take up CO2 at a global scale. Radiocarbon levels in the atmosphere increased strongly due to nuclear bomb testing in the 1950s and early 1960s. The extra 14C that thus became available to plants globally provided the scientists a tool to measure the strength of the carbon uptake by the biosphere. They specifically examined the accumulation of 14C in plants between 1963 and 1967 – a period just after the bomb peak but without further significant nuclear detonations. In this way the authors could assess how quickly carbon is exchanged between the atmosphere and the biosphere.
Reference:
Graven, H. D., Hamish, Warren, H., Gibbs, H. K., Khatiwala, S., Koven, C., Lester, J., Levin, I., Spawn-Lee, S. A., Wieder, W., 2024. Bomb radiocarbon evidence for strong global carbon uptake and turnover in terrestrial vegetation. Science 384,1335-1339. DOI:10.1126/science.adl4443.