Current campus guidelines for any gathering other than academic classes, professional education programs (GTPE), or department meetings are available at

Thursday, December 2 2021
11:00am - 12:00pm
Virtual seminar
For more information:

Dr. Annalisa Bracco

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How many Snowballs out there?

The School of Earth and Atmospheric Sciences Presents Dr. Antonello Provenzale, Institute of Geosciences and Earth Resources, CNR

How many Snowballs out there?

Planetary climates are complex systems that include a multitude of stabilizing (negative) and destabilizing (positive) feedback loops. One of them, the ice-albedo feedback, is possibly causing multiple stable states in Earth’s climate, with the alternation between ice-covered conditions (the most extreme being the so-called Snowball) and warm states. Here, we adopt the view of climate as a dynamical system, strip down its complexity using a simple one-dimensional Energy Balance Model called ESTM and explore the conditions leading to bistability in the climate of Earth-like planets, briefly recalling the potential role of stochastic resonance.

We shall then consider the effects of the ice-albedo feedback for a wide range of orbital and planetary parameters such as distance from the star, ellipticity, obliquity and atmospheric pressure. Other mechanisms for bistability will be mentioned, such as the vegetation-albedo and vegetation-moisture feedbacks, and the crucial role of atmospheric composition. Implications on planetary habitability will finally be considered.

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