56 million years ago, the Earth experienced an exceptional episode of global warming. In a very short time on a geological scale, within 10 to 20’000 years, the average temperature increased by 5 to 8 degrees, only returning to its original level a few hundred thousand years later. Based on the analysis of sediments from the southern slope of the Pyrenees, researchers from the University of Geneva (UNIGE) measured the impact of this warming on river floods and the surrounding landscapes: the amplitude of floods increased by a factor of eight - and sometimes even by a factor of 14 -, and vegetated landscapes may have been replaced by arid pebbly plains. Their disturbing conclusions, to be discovered in Scientific Reports, show that the consequences of such global warming may have been much greater than predicted by current climate models.
56 million years ago, the Earth experienced an exceptional episode of global warming. In a very short time on a geological scale, within 10 to 20’000 years, the average temperature increased by 5 to 8 degrees, only returning to its original level a few hundred thousand years later. Based on the analysis of sediments from the southern slope of the Pyrenees, researchers from the University of Geneva (UNIGE) measured the impact of this warming on river floods and the surrounding landscapes: the amplitude of floods increased by a factor of eight - and sometimes even by a factor of 14 -, and vegetated landscapes may have been replaced by arid pebbly plains. Their disturbing conclusions, to be discovered in Scientific Reports, show that the consequences of such global warming may have been much greater than predicted by current climate models.
The method we relied on to analyse this global warming is directly inspired by cell signaling in systems biology, where researchers analyse the response of cells to external stimuli and the ensuing signal transmission,» explains Sébastien Castelltort, professor in the Department of Earth Sciences at the UNIGE Faculty of Sciences, and leader of the study, in collaboration with researchers from the universities of Lausanne, Utrecht, Western Washington and Austin. «We are interested in how a system, in this case the hydrologic cycle through the behavior of rivers, reacts to an external signal, here the global warming.» This project focused on an extreme climatic case that was well known to scientists: a warming of 5 to 8 degrees that occurred 56 million years ago, between the Paleocene and the Eocene epochs, also known by the acronym PETM (Palaeocene-Eocene Thermal Maximum). Named Earth Surface Signaling System (ESSS) this project is supported by the Swiss National Science Foundation (SNSF).
Read more at Université de Genève
Image: Sébastien Castelltort facing the Eocene Cis conglomerate cliff, near Roda de Isabena, Spain. (Credit: UNIGE)
