This Focus Issue is being published jointly with “Nonautonomous Dynamical Systems: Theory, Methods, and Applications.” We encourage authors to submit their papers to whichever Focus Issue best fits their research.
Climate change is a key challenge of our times. The problem it poses is nonautonomous, since the forcing of the climate system and some of its basic parameters change in time, due to both natural and human causes. Changes in atmospheric concentration of aerosols and greenhouse gases lead to changes in the radiation balance and hence to variations in both globally averaged and regional surface temperatures. The climate system’s instabilities and nonlinearities lead to two complex and unpredictable behaviors even in the better understood autonomous case. The impact of the anthropogenic forcing on the natural variability renders the problem even more complex and unpredictable. In addition, the system’s high dimensionality and heterogeneity lead to further difficulties that require novel and robust methods for describing, understanding, and predicting the system’s behavior over the next decades and centuries.
Considerable advances have been made in the last two decades in applying novel concepts and methods of the theory of nonautonomous dynamical systems, both deterministic and stochastic, to the climate system and to several of its components. These concepts include pullback and random attractors and their invariant measures, and the numerical methods for their exploration are gaining ground. In particular, the systematic derivation of reduced-order models to help the understanding and prediction of the full system have played an important role in advancing our knowledge on the basics of nonautonomous climate processes. The rapid increase in the treatment of tipping points as a natural generalization of classical bifurcations to nonautonomous systems, as well the successful application of algebraic-topology methods to the exploration of time-dependent attractors are but examples of progress in the field.
The goal of this Focus Issue is to review recent progress and stimulate further work on the applications of nonautonomous dynamics to the climate sciences in the broadest sense. The breadth here is understood in terms of both the methods being used and the applications being made. The methods considered will include both analytical and numerical ones for deterministic or stochastic models, while the applications considered will include atmospheric, oceanic, and coupled models, as well as global and regional ones.
Topics covered include, but are not limited to:
- Climate change and climate variability
- Climate projections for decades-to-centuries
- Climate tipping points and early warning signs
- Data assimilation and data-driven methods
- Experimental and large-model studies
- Extremes in a changing climate
- Pullback, snapshot, and uniform attractors
- Regime changes in a changing climate
Dan Crisan, Imperial College London, UK
Stefano Galatolo, Università di Pisa, Italy
Michael Ghil, Ecole Normale Supérieure, France, and University of California at Los Angeles, USA
Stefano Pierini, Parthenope University of Naples, Italy
Denisse Sciamarella, IFAECI, Argentina
Tamás Tél, Eötvös Loránd University, Hungary