Inferring Radiocarbon Production from Tree Rings
This is an on-going research project in which we study cosmic radiations through radiocarbon data in tree rings. Carbon-14 isotope, also called radiocarbon, is produced when cosmic rays interact with particles in the atmosphere. It is known that radiocarbon production rate varies over time, a particularly relevant source of variation for our research is from the activity cycle of the Sun. As radiocarbon is absorbed by trees once it has been produced, tree rings provide an excellent record of radiocarbon content.
In 2012, a team of researchers led by Fusa Miyake discovered spikes in radiocarbon statistics from tree rings implying cosmic radiation orders of magnitudes larger than the biggest solar flares recorded. The origin of these events is still unknown, though the leading theory in the literature points to the Sun. Therefore, these events have the potential to be catastrophic! This research project aims to better our understanding of these events via establishing accessible open-source quantitative models that can be used to study them.
This project is conceived and supervised by Dr Benjamin Pope and funded by the University of Queensland and the Big Question Institute. Some key outcomes from this project are listed below.
Open-Source Software
To interpret radiocarbon data, one needs to model the global carbon cycle.
Currently there is no accessible open-source software for this purpose.
Therefore, we’ve created ticktack,
the first open-source carbon box model package.
Our package can emulate the different models described in the literature,
and via a simple API, it is linked to Bayesian statistics tools.
These features aim to allow transparent and accessible analysis
of radiocarbon data for understanding these events.
Reproducible Quantitative Research
Using ticktack, we obtained the first Bayesian posteriors on key parameters such as event magnitude, arrival date and duration on all known events. Our workflow is managed by a Snakemake repository, which means all of our results are reproducible, transparent and accessible. As a matter of fact, in taking this open-source approach, we hope to stimulate reproducible, quantitative research at this intersection of astrophysics, geology and archeology.
Projects and Experiences