Buying carbon credits is a way for companies to show they’re serious about fighting climate change. But keeping track of these credits is tricky. Now, advocates of the blockchain - the technology that underpins cryptocurrency - say that its digital ledger could be a possible solution to bring transparency to the market. On today’s episode, the FT’s Camilla Hodgson explores whether this technology could help fight climate change or whether some supporters are just in it for their own benefit.