???? These important climatic shifts which have dominated the recent history of the Earth

2023-10-20 11:00:06

Over the last 66 million years, among the climatic shifts characterizing the evolution of our planet’s climate system, two events have played a major role. As part of the European project Types, an international team including scientists from CNRS-INSU (see box), has classified major climate changes by analyzing tipping points (Tipping, in the field of astronautics, is the progressive inclination of a vehicle. ..) associated. Advanced statistical methods were used to analyze two time series of data. is an elementary description, often…) climatic revealing critical climatic transitions.

The results of this study confirm the existence of a hierarchy of events in the evolution of the Earth’s climate system over the last 66 million years. Two major events stand out during this era. The first is the impact of the Chicxulub meteorite about 65.5 million years ago. This event triggered a period of warming with high levels of CO2 in the atmosphere, impacting various environmental changes for 30 million years. The second crucial event took place 34 million years ago, when the glaciation of the southern hemisphere (The southern hemisphere or southern hemisphere is half of the terrestrial globe…) began, following the isolation of Antarctica (L’Antarctica (pronounced [ɑ̃.taʁk.tik] Listen) is the continent furthest…) at the South Pole (The South Pole is the southernmost point on the Earth’s surface, diametrically…). The formation of ice caps induced a much colder climate, subsequently affecting the northern hemisphere. This cold climatic regime persists in which contemporary climate changes occur.

The ice caps formed during this second period are therefore crucial for the current climate. Their destabilization could cause a new tipping point similar to the recurring shifts over the last 66 million years, with the consequence of the advent of a landscape (Etymologically, the landscape is the arrangement of features, characters, shapes of a…) climatic unknown in the history of humanity. Also, strategies for adaptation to climate change and mitigation (Loss of intensity and amplitude of a signal, etc.) of its effects should now take into account the possible destabilization of the tipping elements.

Succession of the two identified climatic regimes: During the last 66 million years delimited by 3 major tipping events, 2 identified by analyzes and a potential third in response to current global warming.
© Denis-Didier Rousseau – Géosciences Montpellier

Statistical analyzes of benthic δ18O from the CENOGRID climate archive (Westerhold et al. 2020).
(a) Time series in Ma BP with difference between the reconstructed and current average global temperature in pink. A first analysis identifies abrupt transitions to warmer climatic conditions in red and colder ones in blue;
(b) Second analysis identifying the two main climate regimes before and after 34 Ma. The main abrupt transitions (TPo) identified are highlighted by red circles and vertical green lines. Highlighted in yellow are the two identified failover events.
© Denis-Didier Rousseau – Géosciences Montpellier