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Tutorial

T9 Physics and Mathematics for the Climate Crisis

The climate is a forced, dissipative, nonlinear, heterogeneous, and non-equilibrium system.

The climate is a forced, dissipative, nonlinear, heterogeneous, and non-equilibrium system. It exhibits natural variability on many spatial-temporal scales, and it is subject to natural as well as anthropogenic external forcings. The urgency of the climate crisis is demanding fundamental advances in our knowledge of the climate, in order to better understand and anticipate extreme events and critical transitions due to tipping points. Nonequilibrium statistical physics, (stochastic) dynamical systems theory, and associated data-driven methods complement each other in helping understand and predict the climate’s evolution. Such a novel viewpoint permits a unified handling of natural climate variability and forced climate change and allows one to clarify Hasselmann’s revolutionary intuition of using the stochasticity associated with fast weather processes to probe the slow dynamics of the climate system.

Topics

  • Climate Variability and Climate Change: We will show how nonequilibrium response theory allows for relating climate variability and climate change, in the spirit of the fluctuation-dissipation theorem. We will also show how it allows for performing climate change projections with numerical climate models and provides a foundation for detection and attribution studies, which aim at causally linking observed climate change with anthropogenic natural drivers.
  • Tipping Points: Critical transitions due to tipping points are a key aspect of climate variability and of the current climate crisis. They have played a key role in the evolution of the biosphere. We will discuss some phenomenological and theoretical aspects of tipping behavior and of its early warning signals, taking advantage of the so-called Koopmanism viewpoint on dynamics.
  • Metastability: We will explore the metastability properties of the Earth system across multiple scales, discussing observational evidence, outputs of numerical simulations, and theoretical analyses, focusing on a) the concept of edge/Melancholia states; b) the statistics and the dynamics of noise-induced transitions between competing metastable states, building on Freidlin-Wentzell theory and the Graham’s quasipotential theory.
  • Extreme Events: We will present large deviation theory as a tool for understanding persistent deviations of climatic fields from long-term averages and for associating them to low-frequency, large-scale patterns. We will also show how rare event algorithms make it possible to explore special dynamical configurations and improve our understanding of high-impact climate events.

Who should attend?

Graduate students, early career researchers, and other scientists who either a) are curious to explore research opportunities in the area of physics and mathematics of climate, or b) are interested in multiscale and metastable complex system; or c) aim at achieving a better understanding of key aspects of the ongoing climatic crisis. The lectures will provide a pedagogical introduction to key problems in climate science and link them to fundamental, wide-ranging ideas of physics. Theoretical, numerical, and observational aspects will be covered.

Organizer

  • Valerio Lucarini, University of Leicester

Presenters

  • Valerio Lucarini, Univ of. Leicester
  • Mickaël Chekroun, Weizmann Inst./UCLA
  • Reyk Börner, Univ of. Reading
  • Francesco Ragone, Univ. Louvain