In the span of the past 66 million years, two significant events have paved the way for potential climate tipping points and the evolution of Earth’s climate system. Should today’s anthropogenic climate change result in complete deglaciation, it could leave a lasting impact on Earth’s climate evolution over geological timeframes, as proposed by researchers Denis-Didier Rousseau from Université Montpellier, France; Witold Bagniewski from Ecole Normale Supérieure, Paris, France; and Valerio Lucarini from the University of Reading, UK. Their study, published in Scientific Reports, forms part of the European TiPES project, focusing on tipping points within the Earth System.
Inspired by a theory of evolution
Drawing inspiration from the theory of punctuated equilibrium, which categorizes evolutionary changes hierarchically, a fresh perspective on the history of climate change has emerged.
Emerging in the 1970s as an alternative to traditional evolution theory, punctuated equilibrium, championed by Eldredge and Gould, proposes that certain evolutionary shifts hold more influence over a species’ evolution. It also elucidates why species tend to adapt through rapid bursts of evolution rather than gradual progression.
Rousseau and his colleagues, pondering the applicability of a similar approach to ranking the significance of pivotal climate shifts, harnessed advanced statistical techniques on two sets of climate data exhibiting evident signs of critical transitions.
The outcomes underscore the potential of hierarchies in comprehending the climate system’s evolution. The study reveals that, out of a series of ten pivotal events, two pivotal occurrences within the past 66 million years have distinctly shaped the course of Earth’s climate system.
A hierarchy of climate tipping events
A pivotal moment, the Chicxulub meteor impact in Mexico, holds historical significance as it triggered the demise of the large dinosaurs around 65.5 million years ago. This catastrophic event ushered in a prolonged era of heightened temperatures and elevated CO2 levels. Over the ensuing 30 million years, this climate pattern set the parameters for permissible climatic shifts, maintaining a consistent state of warm and hot climates.
The second transformative juncture emerged roughly 34 million years ago, linked to the glaciation of the Southern hemisphere. This alteration coincided with the Antarctic continent’s isolation at the South Pole, influenced by dynamic plate tectonics. The resulting expansive ice sheet instigated both Southern and Northern hemisphere glaciation, marking the inception of a notably colder climate regime on Earth. This shift in climate dynamics continued to influence subsequent climate changes.
Furthermore, the analysis underscores the prevailing influence of these past climatic episodes. Even in our present global climate system, remnants of the latter era persist, intricately tied to the existence of massive ice formations forged during the Coolhouse/Icehouse era.
Should anthropogenic global warming prove relentless and overcome the resilience of ice sheets, the resulting deglaciation could mark a significant tipping point akin to the historical landmarks that have shaped Earth’s past. This transition could lead us into an uncharted climate territory.
“Ice sheets are pivotal components of our current climate system, yet their delicate nature renders them highly susceptible. Presently, they exhibit a negative mass balance, and mounting evidence suggests they are melting in response to ongoing climate warming. This trend hints at a potential tipping point that could expedite the retreat of Greenland and West Antarctica, carrying grave consequences for our societies,” warns Rousseau.
The trajectory of climate evolution has often been punctuated by crossing tipping points. Shedding light on the mathematical intricacies of such occurrences, our study facilitates a more profound comprehension. Consequently, strategies for both climate adaptation and mitigation must now factor in the plausible destabilization of these critical elements,” Lucarini emphasizes.