CASUS Distinguished Lecture Series, Prof. Dr. Ulrike Feudel, Professor for Theoretical Physics/Complex Systems, Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University of Oldenburg, Germany

Ulrike studied physics at the Humboldt University in Berlin, where she also completed her doctorate in 1986. She gained her habilitation at the University of Potsdam in 1996 and was appointed a Full Professor for Theoretical Physics/Complex Systems at the Institute for Chemistry and Biology of the Marine Environment of Carl von Ossietzky University in Oldenburg, Germany (2000-present). Ulrike was on long-term research visits at the University of Maryland at College Park, University of California at Santa Barbara (both USA), and Eötvös-Lorand-University Budapest (Hungary).

Her research interests include nonlinear dynamics and chaos theory with applications to climate science, theoretical ecology and neuroscience. She was awarded the Lewis Fry Richardson Medal from the European Geosciences Union 2022, a fellowship for distinguished scientists from the Hungarian Academy of Sciences in 2015, a Heisenberg-Fellowship of the DFG in 1996, among others.

Abstract of the talk// Many systems in nature are characterized by the coexistence of different stable states for a given set of environmental parameters and external forcing. Examples for such behavior can be found in different fields of science ranging from mechanical or chemical systems to ecosystem and climate dynamics. Perturbations, applied to those natural systems can lead to a critical transition from one stable state to another. Such critical transitions — also called tipping phenomena — can happen in various ways: (1) due to bifurcations, i.e. changes in the dynamics when external forcing or parameters are varied extremely slow, (2) due to fluctuations which are always inevitable in natural systems, (3) due to shocks or extreme events [1], and (4) due to rate-induced transitions [2,3], i.e. when external forcing changes too fast compared to the ability of the forced system to follow the changes.

In this talk, Ulrike will discuss these critical transitions and their characteristics and illustrate them with examples from mechanical and natural systems. Moreover, she will relate them to the concept of resilience developed in ecology [4]. Special emphasis is given to non-autonomous systems, in which we highlight the interplay between different time scales, like the dissipative time scale and the time scale of the variation of parameters or forcing. Moreover, Ulrike will discuss the role of unstable states [5], that are not directly observable in nature, but nevertheless act as the organizing centers of the dynamics.

[1] Halekotte L, Feudel U (2020): Minimal Fatal Shocks in Multistable Complex Networks. Sci. Rep. 10, 11783.
[2] Vanselow A, Wieczorek S, Feudel U (2019): When very slow is too fast – collapse of a predator-prey system. J. Theor. Biol. 479, 64-72.
[3] Vanselow A, Halekotte L, Pal P, Wieczorek S, Feudel U (2024): Rate-induced tipping can trigger plankton blooms. Theor. Ecol.
[4] Schoenmakers S, Feudel U (2021) A resilience concept based on system functioning: A dynamical systems perspective. Chaos 31, 053126.
[5] Feudel U (2023): Rate-induced tipping in ecosystems and climate: the role of unstable states, basin boundaries and transient dynamics. Nonlin. Processes Geophys. 30, 481-502

Ulrike Feudel will be talking live in Görlitz. However, as the event is organized in a hybrid format that includes a videoconferencing tool by Zoom Inc., people interested in the topic have the chance to also join the talk remotely. Please ask for the login details via