Noise-induced transitions in climate models: Brownian vs Levy types
Georgios Margazoglou, University of Reading
The current astronomical configuration of Earth supports at least two stable macroscopic climates: the present-day Warm climate, and a globally frozen one, termed Snowball. Geological and paleomagnetic evidence suggests that during the Neoproterozoic era the Earth exhibited at least two major long lasting global glaciation periods. In this talk, we study the impact of adding stochastic forcing in the form of a fluctuating solar irradiance to climate models. Through numerical simulations, we explore the noise-induced transitions between the competing climate states. Viewing the state space as a dynamical landscape with valleys and mountain ridges, we infer the relative likelihood of the identified stable climate states and investigate the most probable transition paths as well as the expected transition times between them. Although in the majority of the considered climate models, we use a Brownian type of noise, in one example we introduce, for the first time in this context, an α-stable Lévy type of noise, and comment on the differences and implications.