Analysis of the tipping point hierarchy shows that two major events over the past 66 million years set the stage for the next climate turning point, and in particular the evolution of the climate system. The authors suggest that if current anthropogenic climate change leads to complete ice loss, this will affect the evolution of Earth’s climate on a geological time scale.

The study, by Denis-Didier Rousseau of the University of Montpellier in France, Witold Bagniewski of the Ecole Normale Supérieure in Paris, France, and Valerio Lucarini of the University of Reading in the United Kingdom, is published in Scientific Reports and is part of the journal Scientific Reports. European research. TiPES project about turning points in the world system.

Inspired by the theory of evolution

A new perspective on the history of climate change was inspired by the discontinuous equilibrium theory, which ranks evolutionary change in a hierarchy.

This idea was put forward by Eldredge and Gould in the 70s as an alternative to the classical theory of evolution. The punctuated balance suggests that some evolutionary changes determine the evolution of one species more than others. This explains why species tend to adapt in short evolutionary leaps over time rather than gradually.

A brief overview of the findings. Credit: TiPES/HP

Rousseau and others. He suggested that a similar approach to ranking the significance of historical climate change resulting from basin events could be just as useful. To do this, they applied advanced statistical methods to two sets of climate data that bear clear signs of critical transitions.

The results indeed show that the idea of ​​hierarchy in the evolution of the climate system can lead to new insights. The analysis shows that two out of ten events marked the evolution of Earth’s climate system over the past 66 million years.

Climate change hierarchy

The first event was the Chicxulub meteor impact that wiped out the large dinosaurs in Mexico about 65.5 million years ago. This disaster marked the beginning of a very hot period with high CO2 levels. For the next 30 million years, this regime dictated what climate change was possible and kept it within a warm and warm climate regime.

The second major event was the tipping point associated with glaciation in the southern hemisphere 34 million years ago, when the Antarctic continent was isolated at the South Pole due to plate tectonics. The formation of a large ice sheet also led to glaciation in the north, marking the beginning of a much colder climate on Earth, once again setting the scale of future climate change.

The analysis also shows that our current global climate system still belongs to the last climate regime and is still dependent on the presence of giant ice floes built during the Coolhouse/Icehouse period.

Serious consequences

If ice sheets fail to withstand anthropogenic global warming, the melting of glaciers will be a tipping point similar to two events in Earth’s history, leading to a new unknown climate environment.

“Ice sheets are essential components of the modern climate system. But they are very fragile. They are currently experiencing a negative mass balance and there are many reports of melting under the influence of continued climate warming, which could at least accelerate the disappearance of Greenland and West Antarctica with serious consequences. It creates a potential tipping point for our societies,” says Denis-Didier Rousseau.

“Overcoming tipping points was part of climate evolution. Our research provides a better understanding of the mathematics of such events. As a result, climate change adaptation and mitigation strategies now need to take into account the possible instability of tipping elements,” adds Valerio Lucarini.