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SUMMARY:Inaugural seminar
DESCRIPTION:We are pleased to announce the inaugural seminar of the Mathema
 tics of Planet Earth research group in the Department of Mathematics at Im
 perial. This will be online (via Zoom) at 1600-1700 on Tuesday 8th June\, 
 given by Professor Valerio Lucarini (University of Reading).  Zoom link w
 ill be provided to the research group mailing list prior to the event.\nPr
 of Valerio Lucarini: Dynamical Landscape and Multistability of a Climate M
 odel\nAbstract\nFor a wide range of values of the incoming solar radiation
 \, the Earth features at least two attracting states\, which correspond to
  competing climates. The warm climate is analogous to the present one\; th
 e snowball climate features global glaciation and conditions that can hard
 ly support life forms. Paleoclimatic evidences suggest that in the past ou
 r planet flipped between these two states\, and possibly additional ones. 
 Here\, we explore the global stability properties of the system by introdu
 cing random perturbations as modulations to the intensity of the incoming 
 solar radiation. We observe noise-induced transitions between the competin
 g basins of attraction. In the weak noise limit\, large deviation laws def
 ine the invariant measure\, the statistics of escape times\, and typical e
 scape paths called instantons. Indeed\, the system lives in an energy-like
  landscape with valleys and mountain ridges defined by the Graham’s quas
 ipotential. For low (high) values of the solar irradiance\, the zero-noise
  limit measure is the snowball (warm) climate. The changeover between the 
 two regimes corresponds to a first-order phase transition in the system. W
 e then compare the results obtained using the theory of quasipotentials wi
 th what can be obtained using a bottom-up approach. Harnessing techniques 
 from data science\, specifically manifold learning\, we characterize the d
 ata landscape to find climate states and basin boundaries within a fully a
 gnostic and unsupervised framework. Both approaches show remarkable agreem
 ent\, and reveal\, apart from the well known warm and snowball earth state
 s\, a third intermediate\, new stable state in one of the two climate mode
 ls we consider. The combination of our approaches allows to identify how m
 acroscopic\, physical properties of the climate system – the role of the
  ocean heat transport and of the hydrological cycle – drastically change
  the topography of the dynamical landscape of Earth’s climate. The frame
 work we propose seems of general relevance for the study of complex multis
 table systems with multiple scales of motions.\nRefs:\nG. Margazoglou\, T.
  Grafke\, A. Laio\, V. Lucarini\, Dynamical Landscape and Multistability o
 f the Earth’s Climate\, Proc. R. Soc. A\, in press (2021)\nM. Ghil\, V. 
 Lucarini\, The Physics of Climate Variability and Climate\, Rev. Modern Ph
 ysics\, 92\, 035002 (2020)\nV. Lucarini\, T. Bodai\, Global Stability Prop
 erties of the Climate: Melancholia States\, Invariant Measures\, and Phase
  Transitions\, Nonlinearity 33 R59 (2020)\nV. Lucarini\, T. Bodai\, Transi
 tions across Melancholia States in a Climate Model: Reconciling the Determ
 inistic and Stochastic Points of View\, Phys. Rev. Lett. 122\,158701 (2019
 )\nV. Lucarini\, T. Bodai\, Edge States in the Climate System: Exploring G
 lobal Instabilities and Critical Transitions\, Nonlinearity 30\, R32 (2017
 )\n 
URL:https://www.imperial.ac.uk/events/135280/inaugural-seminar/
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LOCATION:United Kingdom
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