Because the coffee bean is in danger. A rapidly spreading fungus is threatening both the plants themselves and the farmers who make a living from them. The fungicides that used to stop it no longer work in many cases and climate change is making life easier for the fungus every day in areas where coffee grows.

How long until there's a coffee shortage? Or until we start losing some of the more unique varieties? We don't know, but there is still time to fight the problem.

GUEST: Maryn McKenna, science journalist and author