Prof. Ulrike Feudel, Carl von Ossietzky University of Oldenburg
Tipping phenomena and resilience in complex systems
January 30, 2023 – 8:30 PM IST
Many systems in nature are characterized by the coexistence of different stable states for a given set of environmental parameters and external forcing. Examples of such behavior can be found in different fields of science ranging from mechanical or chemical systems to ecosystem and climate dynamics. As a consequence of the coexistence of a multitude of stable states, the final state of the system depends strongly on the initial condition. Perturbations, applied to those natural systems can lead to a critical transition from one stable state to another. Such critical transitions are called tipping phenomena in climate science, regime shifts in ecology, or phase transitions in physics. Such critical transitions 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 that are always inevitable in natural systems, (3) due to rate-induced transitions, i.e. when external forcing changes on a characteristic time scale comparable to the time scale of the considered dynamical system and (4) due to shocks or extreme events. We discuss these critical transitions and their characteristics and illustrate them with examples from mechanical and natural systems. Moreover, we discuss the concept of resilience, which has been originally introduced by C.S. Holling in ecology, and reformulate it in terms of dynamical systems
Ulrike Feudel studied Physics and got her Ph.D. at Humboldt University Berlin, Germany. She got her habilitation at Potsdam University, Germany. Now she is a professor of Theoretical Physics/Complex Systems at the University of Oldenburg, Germany. Her research covers different topics in nonlinear dynamics and complex systems like multistability, tipping phenomena, extreme events, and pattern formation with applications to environmental science like population dynamics, climate science, and biological activity and particles in fluid flows. She was a long-term visitor at the University of Maryland at College Park (USA), University of California at Santa Barbara (USA), and the Eötvös University Budapest (Hungary). She was awarded the Lewis Fry Richardson medal by the European Geosciences Union in 2021, a fellowship for Distinguished Scientists by the Hungarian Academy of Sciences in 2015 and was the Burgers Professor for Hydrodynamics at the University of Maryland at College Park in 2013.