We published a new paper on early warning signals of the termination of the African Humid Period(s) in the journal Nature Communications. A very close look at the sediments of the Chew Bahir Basin in South Ethiopia provides new insights into the structure of climate transitions in Africa. Wet climate did not simply become drier; it flickered rapidly between wet and dry, which posed major challenges for the humans in the region.
The palaeoclimate data were measured on two parallel, almost 300 m long sediment cores, which we obtained in 2014 in the Chew Bahir Basin. We cannot measure climate directly, but work with so-called climate proxies, i.e. physical, chemical and biological signals that are more or less directly related to the climate of the past. One of these climate proxies is the potassium concentration of the sediments, which increases in the course of a transformation of two clay minerals, smectites and illites, with increasing evaporation of the lake in a dry climate.
The temporal course of the potassium concentration in the core, totalling more than 55,000 measured values, was analysed using recurrence plots / recurrence quantification analysis, among other things, in order to understand the dynamics of climate variability in the region during the last 620,000 years.
All analyses were carried out using MATLAB and several toolboxes. A Zenodo repository contains all original data as well as all MATLAB scripts to reproduce the figures in the article. The reader is thus able, as part of the Open Science Initiative, to make changes to the MATLAB code, e.g. to change the input arguments of the recurrence plots, in order to learn to what extent the results depend on these settings.
Data and code
https://zenodo.org/records/10624471
Photo credits
Verena Förster-Indenhuck, U Köln
References
Trauth, M.H., Asrat, A., Fischer, M.L., Hopcroft, P.O., Foerster, V., Kaboth-Bahr, S., Kindermann, K., Lamb, H.F., Marwan, N., Maslin, M.A., Schaebitz, F., Valdes, P.J. (2024) Early Warning Signals of the Termination of the African Humid Period(s), Nature Communications, 15, 3697. DOI: 10.1038/s41467-024-47921-1.
Trauth, M.H. (2024) Behind the paper – Flickering before tipping: Climate transitions in northeastern Africa follow a similar pattern over the last 620 thousand years, SpringerNature Research Communities.
Trauth, M.H., Asrat, A., Maslin, M.A. (2024) Africa dramatically dried out 5,500 years ago – our new study may warn us of future climate tipping points, The Conversation.