Master thesis - Droughts in the last millennium
This photo shows a farmer and his two sons during a dust storm in Cimarron County, Oklahoma, 1936. The 1930s Dust Bowl drought had four drought events with no time to recover in between: 1930-31, 1934, 1936 and 1939-40. Credit: Arthur Rothstein, Farm Security Administration. Image and caption text taken from https://climate.nasa.gov/news/2175/nasa-study-finds-1934-had-worst-drought-of-last-thousand-years/
Background
There is a current scientific debate if the intensity of the recent 2003, 2015, and 2018 droughts is exceptional in the context of the last millennium. Based on tree-ring reconstructions, some authors find them to be within the range of natural variability (Ionita et al. 2021), while others describe them to be unprecedented (Büntgen et al. 2021). Our new climate reconstructions, generated by data-informed climate model simulations enable a testing of these hypotheses (Hand et al., 2023).
Aim
The goal of this thesis is the analysis of droughts in our new climate reconstruction, which combines various kinds of direct and indirect observations with model simulations since 1420 CE. The drought magnitude will be quantified by considering cumulative water deficits and the long-term statistics of drought event magnitudes will be established. The climate reconstruction (from observations-informed climate model simulations) would allow to study also possible causes like Atlantic sea surface temperature variability or shifts in large-scale atmospheric circulation.
Requirements
- Interest in working with large datasets from climate model outputs.
- Experience working with R or other data science tools are an advantage.
- The student writes the thesis in English.
Supervision
- Prof. Benjamin Stocker, Prof. Stefan Brönnimann
References
- Hand, R., Samakinwa, E., Lipfert, L., and Brönnimann, S.: ModE-Sim – a medium-sized atmospheric general circulation model (AGCM) ensemble to study climate variability during the modern era (1420 to 2009), Geoscientific Model Development, 16, 4853–4866, https://doi.org/10.5194/gmd-16-4853-2023, 2023.
- Ionita, M., Dima, M., Nagavciuc, V. et al. Past megadroughts in central Europe were longer, more severe and less warm than modern droughts. Commun Earth Environ 2, 61 (2021). https://doi.org/10.1038/s43247-021-00130-w
- Büntgen, U., Urban, O., Krusic, P.J. et al. Recent European drought extremes beyond Common Era background variability. Nat. Geosci. 14, 190–196 (2021). https://doi.org/10.1038/s41561-021-00698-0
