Hugo Bucher : Temps profond perspective globale pour les changements actuels futurs en biodiversité

With the extinction of nearly 90% of marine species within a period of approximately 50,000 years, the largest mass extinction in the history of life occurred 251 million years ago, forming the sharp boundary between the Paleozoic and Mesozoic eras. This natural event provides valuable insights into the mechanisms that regulate biodiversity over the long term (more than 10,000 years) and allows us to place current short-term variations in biodiversity, climate, and the carbon cycle within a longer timeframe and on a global scale. Following a major initial disturbance of volcanic origin, a succession of three successive cycles of extinction and diversification, linked to the intrinsic functioning of the carbon cycle out of equilibrium during the rebuilding of the biological pump (biomass of primary producers), explains the 5 million-year delay required to regain a globally stable environment, enabling the evolution of complex ecosystems such as reefs. The destruction of natural habitats and biomass, in conjunction with the dynamic, unbalanced behavior of the carbon cycle, are the fundamental causes of these successive extinctions. A single episode of geologically brief but massive pollution of extrinsic origin (volcanism, anthropogenic volatiles) pushing the carbon cycle out of equilibrium, accompanied by the destruction of primary production, which normally acts as a buffer for this cycle, can therefore lead to repeated major extinction crises in parallel with extreme climatic cycles. Speaker Geologist and paleontologist Dr. Hugo Bucher and his multidisciplinary team (paleontology, paleoecology, stable and radiogenic isotope geochemistry, ocean-atmosphere climate modeling) have been working for some twenty years on the largest mass extinction (Permian-Triassic boundary) and the long restoration of biodiversity that followed. Based at the University of Zurich for paleontology, the multidisciplinary extensions of this work also involve teams from the Universities of Lausanne and Geneva, with fieldwork conducted worldwide. This research receives regular support from the Swiss National Science Foundation (SNSF), and the team led by Hugo Bucher is at the forefront of international research on mass extinctions and the role of biotic-abiotic interactions in biological evolution. Institutes Paläontologisches Institut und Museum der Universität Zürich, D-ERDW ETHZ Scientific Advisor FREETHEBEES Publications See: https://www.pim.uzh.ch/institut/mitar...