Writer and broadcaster Ed Conway discusses his book "Material World: The Six Raw Materials That Shape Modern Civilization," which explores the critical role of six raw materials — salt, iron, copper, oil, lithium and silicon— in shaping modern civilization. Then, science journalist Humberto Basilio talks about the relative stability or instability of the system of ocean currents called the Atlantic Meridional Overturning Circulation, AMOC, which is a system of ocean currents that circulates water within the Atlantic Ocean.