Tim Lenton - Revolutions that made the Earth

Tim Lenton, Professor of Earth System Science at the University of Exeter, discusses how our remarkable planet came to be the way it is now.

About Tim Lenton "I’m Director of the Global Systems Institute and Professor of Earth System Science at the University of Exeter. My work focusses on the transformation of our planet.

Reading Jim Lovelock’s books on Gaia ignited my passion for studying the Earth as a whole system. I study how our remarkable planet came to be the way it is now. I study how humans are transforming the Earth’s system and how we might create a flourishing future within that system."

Key Points

• There are three remarkable revolutions that made the Earth in which we could evolve as humans. The first is the origin of life. The second is the creation of oxygen in our atmosphere. The third is the makings of complex life forms. • Humans are the first conscious animal species to have a truly global influence on the climate. • The remarkable thing about our planet and what we call the Earth system is how interconnected the living and the non-living things are at the surface of the planet: Life has transformed the environment, and the environment has shaped life. • We recognise that we’re a global force and we’ve created a new geological epoch, which scientists have dubbed “The Anthropocene” that is destined to end badly. But humans could also be the beginning of another revolutionary change of the Earth.

The Earth's first revolution

There are three remarkable revolutions that made the Earth in which we could evolve as humans. The first is the origin of life. The second is the creation of oxygen in our atmosphere. The third is the makings of complex life forms and a second rise in oxygen to levels that can support creatures like us that are intelligent enough to reflect on this remarkable history from which we’ve evolved.

Life got started on this planet over three and a half billion years ago and it was immediately faced with a profound problem of trying to get hold of enough of all the elements it needed to build its bodies, because the supply from inside the Earth – from volcanoes and the like – of the materials that organisms use was pretty meagre. So, the first revolution was really a revolution of recycling, where the young biosphere learned how to recycle all the elements it needed to flourish, and to be productive and global in extent and influence. 

Now, after that revolution, at least a billion years passed before one little lineage of bacteria solved an incredible puzzle of how to pull apart water molecules, to get hold of electrons and stick those electrons on molecules of carbon dioxide to reduce the carbon down to sugars, in what we know as photosynthesis. And that process spits out oxygen as a waste product.