Vietnam's robusta: the go-to coffee bean in a warmer world?

Bitter and earthy. Fit for instant brews only. Robusta coffee has a dire reputation, but a small group of farmers in Vietnam is trying to turn the bean’s fortunes around as a warming world threatens the industry.

As an interior designer in trendy Ho Chi Minh City, Tran Thi Bich Ngoc, 42, largely stayed clear of Vietnamese coffee, puzzling over why it didn’t taste as good as cups from abroad.