This week: A love story about concrete. Melissa and Rebecca Dell, an industrial decarbonization expert, break down our relationship with concrete, and why it’s so dysfunctional. The problem? Making concrete – especially its key ingredient, cement – is toxic to the climate. Only two countries in the world – the US and China – produce more greenhouse gas emissions than the concrete industry as a whole.   So what do we do about this toxic relationship? Do we cut ties? Do we try to mend it? Rebecca explains concrete – and how it’s different from cement – with an amazing Rice Krispy analogy. Producer Daniel Woldorff heads to a concrete plant to see some low-carbon technology in action. And Rebecca walks us through our options for reducing carbon emissions in concrete.  Guest: Rebecca Dell directs the industry program at the ClimateWorks Foundation. She works on ways to remove carbon pollution from industries like concrete, steel and chemicals. The Big Switch is produced by Columbia University's Center on Global Energy Policy in partnership with Post Script Media. This episode was produced by Alexandria Herr and Daniel Woldorff. Theme music and mixing by Sean Marquand. Story editing by Anne Bailey. A special thanks to Natalie Volk, Kirsten Smith and Kyu Lee. Our executive editor is Stephen Lacey.