The climate system and its main constituents, such as atmosphere and oceans, are highly complex dynamical systems with a wide range of spatio-temporal scales. Because of their complexity and multiscale character, analysis of these systems is challenging and often involves numerical simulation. Modern developments in modeling and simulation of the climate system include the use of multiscale methods and/or stochastic modeling for representing small-scale processes in computational models of large-scale atmosphere/ocean flow. Another newly emerging research direction is the development of methodologies for analysis and efficient simulation of extreme events such as heat waves, often employing the theory of large deviations. This minisymposium will feature presentations that highlight these developments both from a theoretical and from more applied perspectives.