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Tipping Points in the Climate System: Automatic Detection of Abrupt Transitions in Paleoclimate Records
  • Witold Bagniewski,
  • Michael Ghil,
  • Denis-Didier Rousseau
Witold Bagniewski
École Normale Supérieure and PSL University

Corresponding Author:[email protected]

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Michael Ghil
École Normale Supérieure and PSL University
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Denis-Didier Rousseau
École Normale Supérieure and PSL University
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Abstract

Bifurcations and tipping points (TPs) are an important part of the Earth system’s behavior. These critical points represent thresholds at which small changes in the system’s parameters or in the forcing abruptly switch the system from one state or type of behavior to another. Current concern with TPs is largely due to the potential contribution of anthropogenic forcing to one or more climatic subsystems undergoing such abrupt, and possibly irreversible, transitions. Paleorecords of past climate have been shown to contain abrupt transitions, or “jumps,” which may represent former instances of tipping. Robustly identifying and describing such transitions is essential to properly understanding the underlying bifurcation mechanisms. Doing so may provide valuable information for identifying critical TPs in current and future climate evolution.Here we present a robust methodology for detecting abrupt transitions in proxy records that is applied to a set of ice core, speleothem, and marine sediment records of the last climate cycle and the Holocene. This methodology is based on the nonparametric Kolmogorov-Smirnov (KS) test for the equality, or not, of the probability distributions associated with two samples drawn from a time series, before and after any potential jump. The KS test is augmented by several other criteria and it is evaluated against other jump detection algorithms, aiming to establish a “gold standard” for abrupt-transition detection. This objective approach to identifying climate TPs will allow us to construct better nonlinear and stochastic models of bifurcations in the Earth’s climate and its interactions with ecosystems within the TiPES (Tipping Points in the Earth System) EU-funded project.