Hierarchy of abrupt transitions in the past climate

• Main Authors: Rousseau, Denis-Didier, Bagniewski, Witold
• Format: Report
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDE.MCG]Environmental Sciences/Global Changes; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-03713538; https://hal.archives-ouvertes.fr/hal-03713538/document; https://hal.archives-ouvertes.fr/hal-03713538/file/cascade_V17.pdf

The Earth's climate has experienced numerous abrupt and critical transitions during its long history. Such transitions are evidenced in accurate, high-resolution records covering different timescales. This type of evidence suggests the possibility of identifying and ranking past critical transitions, which yields a more complex perspective on climatic history. Such a context allows defining dynamical climate landscapes with multiscale features. To illustrate such a richer structure of critical abrupt transitions, we have analyzed 2 key high-resolution datasets: the CENOGRID marine compilation covering the past 66 Myr, and North Atlantic U1308 record representing the past 3.3 Myr. Our aim was to examine objectively the observed visual evidence of abrupt transitions and to identify among them, applying the augmented Kolmogorov-Smirnov test and the recurrence analysis, the key thresholds indicating regime changes that differentiate among major clusters of variability. This identification is replaced chronologically and discussed after comparison with major climate factors. A potential hierarchy in the observed thresholds is proposed through a domino-like succession of abrupt transitions, corresponding to as many bifurcations, that shaped the Earth's climate system over the past 66 Ma.