Christian has a broad spectrum of research interests in the general area of data-driven analysis and stochastic modelling of complex systems, with applications to real-world problems. Main examples of recent research include statistical methods for sustainable energy systems, the analysis of frequency fluctuations in power grid networks, spatio-temporal analysis of air pollution data, the statistics of plane delays, and environmental problems. Christian has made important contributions to the understanding of equilibrium states and stationary nonequilibrium states of complex systems, introducing (together with E.G.D. Cohen, Rockefeller University New York) so-called superstatistical techniques, which by now have become an established method in nonequilibrium statistical physics. He is an expert in dynamical systems, stochastic processes, data-driven approaches to complex systems, spatio-temporal chaotic dynamics, stochastic modelling techniques, and interdisciplinary applications.