???? The Greenletter Club is 100% independent, to help us, it's here ???? https://bit.ly/3ppLx68 ⚠️ The episode is a bit complex - accessible to everyone - but deserves to be listened to in good conditions. ???? ❄️ ???? Iceball Earth, hyperactive volcanism or the Green Sahara period: over the last few billion years, and up until a few millennia ago, the Earth has experienced climates very different from those of today, essential periods to understand in order to anticipate climate change. Hence this question: what were the climates of our planet? To answer it, we welcome Gilles Ramstein, paleoclimatologist, research director at the French Alternative Energies and Atomic Energy Commission (CEA). (LSCE [CEA/CNRS/UVSQ]), and author of Voyage à travers les climats de la Terre. *** Interview with Gilles Ramstein by Maxime Thuillez Follow the Greenletter Club: ????Site: https://greenletterclub.fr/ ????Instagram: instagram.com/greenletterclub/ ????Twitter: twitter.com/GreenletterClub ???? Youtube: https://bit.ly/3qnP6o5 CHAPTERS 00:00 INTRO 00:53 - Hello Gilles Ramstein, can you explain your background and what paleoclimatology is? What is the point of studying past climates? 04:52 - What are the elements that can vary the Earth's climates? We talk about CO2, plate tectonics, the power of the sun, orbital parameters... 09:15 - The culprit that you don't name is CO2... and generally greenhouse gases like methane or others. In climate history, what is the role of greenhouse gases? 13:25 - How did water appear on Earth? 15:58 - Water arrives on Earth with comets and asteroids... the Earth is then a vast aquaplanet. When does life arrive on Earth? 17:30 - Greenhouse gases prevented the Earth from freezing over... and yet the Earth will end up becoming a ball of ice. How did this happen? What did the Earth look like at that time? 26:45 - The planet is a terrestrial planet, which becomes an aquaplanet, then a fairly basic life made of archaea and bacteria emerges, the Earth then enters glaciation... and then around 500 million years ago, there is an explosion of life. What happened at that time? 31:13 - In past climates, there will be about twenty major extinctions, including five major ones. There is one that interests us more particularly, that of the extinction of the dinosaurs. We have heard a lot about this: the effect of a meteorite, the role of volcanism. Do we know clearly what caused the disappearance of the dinosaurs? 36:13 - We will move forward to our era, which is called the glacial paroxysm... what did the Earth look like 20,000 years ago? 40:45 - At that time, there were two additional ice caps, over Canada and northern Europe, and the sea level was 120 meters lower? We could go to England on foot!? 42:00 - Glaciation is slow, but the melting of these two ice caps was very rapid? 43:40 - There is a period in the Holocene called the Green Sahara... less than 10,000 years ago, the Sahara was not a desert? 47:32 - The Flood is a myth that can be seen in many civilizations, in the Middle East, but also in India. What could have - in past climates - explained this myth? 48:54 - Man is going to modify the amount of CO2 in the atmosphere... The Greenland ice cap is melting, as is part of Antarctica. Is the melting of these ice caps inexorable? Will they melt quickly? 54:59 - As a climatologist, what worries you the most? How worried are you about the future of life on Earth?