The Physics of Climate Variability and Climate Change

TL;DR

This paper reviews the complex, nonlinear nature of the climate system, integrating observational evidence, modeling approaches, and recent advances in dynamical systems and statistical physics to enhance understanding and prediction of climate variability and change.

Contribution

It uniquely combines dynamical systems theory and nonequilibrium statistical physics to provide a unified framework for understanding climate variability and forced change.

Findings

Integration of dynamical systems and statistical physics enhances climate modeling.

Unified treatment of natural variability and anthropogenic forcing.

Improved understanding of climate sensitivity and predictability.

Abstract

The climate system is a forced, dissipative, nonlinear, complex and heterogeneous system that is out of thermodynamic equilibrium. The system exhibits natural variability on many scales of motion, in time as well as space, and it is subject to various external forcings, natural as well as anthropogenic. This paper reviews the observational evidence on climate phenomena and the governing equations of planetary-scale flow, as well as presenting the key concept of a hierarchy of models as used in the climate sciences. Recent advances in the application of dynamical systems theory, on the one hand, and of nonequilibrium statistical physics, on the other, are brought together for the first time and shown to complement each other in helping understand and predict the system's behavior. These complementary points of view permit a self-consistent handling of subgrid-scale phenomena as stochastic processes, as well as a unified handling of natural climate variability and forced climate change, along with a treatment of the crucial issues of climate sensitivity, response, and predictability.