Coffee beans generally come from one of two species: Arabica and Robusta.
The former tends to be better known: Brands love touting their use of Arabica beans because they offer more delicate flavors. Less expensive and bitterer, Robusta tends to be a workhorse bean used when keeping down costs. But though many coffee blenders might see Robusta as a backup option, new research suggests that both share a troubling similarity: They may both be susceptible to climate change.
The wordplay inspired title of the paper, published earlier this year in the journal Global Change Biology, says it all: “Not so robust: Robusta coffee production is highly sensitive to temperature.” “Coffea canephora (Robusta coffee) is the most heat tolerant and ‘robust’ coffee species and therefore considered more resistant to climate change than other types of production coffee,” the authors write. “However, the optimum production range of Robusta has never been quantified, with current estimates of its optimal mean annual temperature range (22‐30 °C) based solely on the climatic conditions of its native range in the Congo basin, Central Africa.”
Understanding the level to which Robusta beans—which accounts for about 40 percent of the world’s coffee production—is susceptible to climate change is important because the susceptibility of Arabica beans—which account for the remaining 60 percent—has raised serious concerns. A report from last year suggested that global warming could threaten Arabica beans with extinction.
This new research doesn’t appear to push the idea of extinction, but the study does suggest reasons for concern. Looking at a decade of yields across nearly 800 farms, the authors found that relatively small temperature variations can have a significant effect on yields. Specifically, every one degree Celsius change from the optimal temperature range decreased yields by about 14 percent. “Our results suggest that Robusta coffee is far more sensitive to temperature than previously thought,” the paper states. “Robusta supplies 40 percent of the world’s coffee, but its production potential could decline considerably as temperatures increase under climate change, jeopardizing a multi‐billion dollar coffee industry and the livelihoods of millions of farmers.”
Still, writing for Massive Science, Rebecca Dzombak—a Ph.D. candidate in biogeochemistry at the University of Michigan who wasn’t involved in the study—suggested the news wasn’t as bad as it could be. “Even though Robusta’s temperature range may be cooler than previously thought, it is still better adapted to swings in climate than Arabica,” she explained. “Planting shade trees and harvesting coffee from the slow-growing understory are relatively easy changes. Coffee plants can also be specifically bred based on climate change-friendly traits, like larger root systems and efficient stress responses, which will help coffee growers keep their yields high.”
So though Robusta may be more sensitive to temperature than previously thought, it’s still less sensitive than Arabica—which could be a small silver lining for anyone who likes extremely intense and bitter coffee.
