Zainab Bello was 24 when she left her PhD programme with a jar of grey powder and a conviction that construction could become a carbon sink.
Why cement?
Because Africa will build more in the next thirty years than in the last three hundred, and almost nobody outside the industry thinks about what it is made of.
What does it feel like to top the Next 50?
Like a deadline. Lists are lovely, but the climate does not read them.