Waterworld - James Jackson's 1995 Christmas Lectures 5/5

Water is an essential ingredient of the Earth, and without it, we would not be here. Watch all the lectures in this series here: https://youtube.com/playlist?list=PLbnrZHfNEDZzN4JcqnWDW02rO0gJU7qBx&si=lmo1ZuOBkecGK5Rq Watch our newest Christmas lectures here: https://www.youtube.com/playlist?list=PLbnrZHfNEDZyQJZLPMjwEoOLdkFBLU2m1 This was recorded on 4 Dec 1995. -- 2025 and 2026 mark 200 years of the Royal Institution Christmas Lectures — a world famous series showcasing science, curiosity, and mind-blowing demos, and started by the legendary Michael Faraday himself. To celebrate, we're unlocking the archive. Every week, we’ll upload a classic lecture to our YouTube channel — some not seen since they aired on TV. Sign up as a Science Supporter and get early access here: https://www.youtube.com/channel/UCYeF244yNGuFefuFKqxIAXw/join -- From the 1995 programme notes: Water is an essential ingredient of the Earth, and without it we would not be here. Water reshapes our planet's surface through erosion and chemical weathering and, although we take it for granted, the position of the shoreline is one of the most changeable of all geological features. Although it may not feel like it, we are living in an ice age now. At the moment we are in a warm period, and the sea level is high, but just 20,000 years ago much of northern Europe was covered in ice and we could walk to France. Such fluctuations in climate have caused sea levels to vary by as much as 120 metres over the last two million years. One of the most astonishing recent discoveries is that the history of global sea level over this period is contained in the composition of tiny organisms preserved as fossils on the seafloor, and, furthermore, that the growth and decline of the ice sheets are related to the nature of the Earth's orbit around the Sun. When we look at our neighbours, the Moon, Venus and Mars, we can imagine what the Earth would be like if we had no water, or if we lost it, or if the Earth's surface was not in the temperature range for water to be liquid. We are no longer restricted to the study of just our own planet. Space exploration has made us much more conscious of variations on our own theme: how small changes to the conditions on Earth can produce quite different geological environments, even though the processes that are operating are often recognisable. We are becoming much more aware of how special the Earth is. -- About the 1995 CHRISTMAS LECTURES Catastrophes such as volcanic eruptions, earthquakes, climate change and sea level rise are starting to have a huge impact on our lives as our population increases and we colonise every available corner of the world, particularly the coastlines. Yet at the same time these phenomena, which are disasters to us, are a natural part of the way the Earth behaves. We can use them as tools to see deep inside the Earth, to see how the planet is put together, and how it changes with time. Scientists used to see the Earth as a planet whose surface had been the victim of random and unexplained events, such as mountain building and changing climate. Now we know that what we see at the surface is caused by vigorous motions deep inside the Earth — motions that are slow compared with our lifetimes, but are very fast compared with the life of the Earth itself. Far from living on a dead lump of rock in Space, we are living on jelly, but didn't realise it! These lectures trace the story of how and why our views changed — from a fumbling suspicion that continents had moved around, through a detailed reconstruction of how the pieces fit together, to the present, where we can measure the motions directly and see them going on. Find out more about the CHRISTMAS LECTURES here: https://www.rigb.org/christmas-lectures --- Join this channel to get access to perks: https://www.youtube.com/channel/UCYeF244yNGuFefuFKqxIAXw/join Subscribe for regular science videos: http://bit.ly/RiSubscRibe The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and TikTok: https://www.tiktok.com/@ri_science Listen to the Ri podcast: https://podcasters.spotify.com/pod/show/ri-science-podcast Donate to the RI and help us bring you more lectures: https://www.rigb.org/support-us/donate-ri Our editorial policy: https://www.rigb.org/editing-ri-talks-and-moderating-comments Subscribe for the latest science videos: http://bit.ly/RiNewsletter Product links on this page may be affiliate links which means it won't cost you any extra but we may earn a small commission if you decide to purchase through the link.