Our guest today is Mark Williams who is a professor of paleobiology at the University of Leicester. He’s the co-author, along with Jan Zalasiewicz of The Goldilocks Planet: The 4 billion year story of Earth's Climate and has published several peer reviewed papers on paleobiology, paleoenvironments and paleoclimates in conjunction with other researchers including his latest ‘The Anthropocene Biosphere’ which explores the impact of humans from a geological perspective on the biosphere. It also looks at how humans are potentially driving a sixth mass extinction and this will be the topic of our discussion today.