To understand the world you need to understand the ocean. That’s the argument of physicist Helen Czerski who has long studied the complex ecosystems and forces that drive the ‘blue machine’ which covers 71% of our planet. Czerski joins Intelligence Squared to discuss her new book Blue Machine: How the Ocean Shapes Our World, and what we should know about these vast bodies of water – the waves, currents, invisible ocean walls and underwater waterfalls that are part of an interlinked system that shapes the world around us. In conversation with science editor of The Times Tom Whipple, Czerski discusses how, since the beginning of human civilisation, the oceans have been central to the way human societies have evolved and how threats like climate change and overfishing could threaten our future.  We’d love to hear your feedback and what you think we should talk about next, who we should have on and what our future debates should be.  Send us an email or voice note with your thoughts to podcasts@intelligencesquared.com or Tweet us @intelligence2.  And if you’d like to get ad-free access to all Intelligence Squared podcasts, including exclusive bonus content, early access to new episodes and much more, become a supporter of Intelligence Squared today for just £4.99, or the equivalent in your local currency .  Just visit intelligencesquared.com/membership to find out more.  Learn more about your ad choices. Visit podcastchoices.com/adchoices