Regulation and deregulation of Earth climate system from deep past to Anthropocene

Speaker : professor Gilles Ramstein from the Laboratoire des Sciences du Climat et de l’Environnement (IPSL) in Paris

This talk will be devoted to explore how climate, hydrological cycle and atmospheric CO2 have changed during Earth history. Since 4 billion of years the climate on Earth has indeed evolved but most of the time, hydrology and temperature at the surface of the Earth have been regulated by processes that are different for each time scale. The billions of year climate evolution is mostly driven by sun luminosity increase. The tens of millions of year of climate evolution is mostly driven by tectonics and associated CO2 evolution. Finally at higher frequencies: from ten to hundreds of thousand years, the climate is mostly driven by astronomical parameters. We will explore these deep time climate and atmospheric CO2 evolution focusing on regulation but also on drastic climate changes that occurred in Earth History. We will finish this talk considering the present day period when human became the major actor of climate change; modifying his environment much faster than previous natural forcing factors did.