Hairy berries. Supersize seeds. No caffeine. Compared with the beans that supply our daily brew, the wild relatives of coffee plants can seem downright bizarre. But they also harbor genetic traits that could help farmed coffee plants survive threats such as drought and disease—and maybe create pleasing new cups in the process. Now, a new pair of studies says up to 60% of these wild coffee species could go extinct, some in the next 10 to 20 years, thanks to deforestation, human settlement, and climate change.
There are 124 known species in the genus Coffea, but most of us drink domesticated versions of only two: tasty C. arabica, which accounts for two-thirds of the global market, and hardy C. canephora, better known as robusta, which comprises the rest. But arabica is especially susceptible to diseases, such as the devastating coffee leaf rust fungus, and arabica-robusta hybrids that were once resistant are beginning to succumb as well.
To map the locations and health of wild coffee species, Aaron Davis, head of coffee research at the Royal Botanical Gardens, Kew in the United Kingdom, and colleagues conducted the most comprehensive global assessment to date. They started with more than 5000 records of wild species compiled by other researchers and explorers, and they collected further data during dozens of expeditions to key areas in Africa, Madagascar, and Indian Ocean islands.
After mapping the location of each species, they determined—based on plant population and habitat—which were at risk. Sixty percent were threatened with extinction, and some might already be extinct, they report this week in Science Advances. “We knew it would be high, but we didn’t actually think it would be that high,” Davis says. For comparison, 22% of all plant species worldwide are threatened.
In a separate study, Davis teamed up with other researchers from Kew and the Environment, Climate Change, and Coffee Forest forum in Addis Ababa for an in-depth look at wild arabica, which was at low risk in the global analysis. Their new study, unlike the old, factored in climate change, using remote sensing data and computer modeling. It proved to be crucial: They found that climate change could cut the population of wild arabica in half by 2080, the researchers report this month in Global Change Biology. The finding suggests that other seemingly low-risk wild coffee species could in fact be at even higher risk, Davis says.
The new papers “strengthen what we know” about the vulnerability of wild coffee species, says Sarada Krishnan, director of global initiatives at the Denver Botanic Gardens and the owner of a coffee plantation in Jamaica. Two years ago, Krishnan and other scientists investigated one way of keeping wild coffee species alive: through gene banks. These repositories house genetic material that can be grown back into plants should their wild cousins be wiped from the face of the earth.
The most famous repository is the “doomsday” seed vault on Spitsbergen in Norway. But coffee seeds will not germinate after being frozen. Instead, plants have been haphazardly conserved in 52 field collections in coffee-growing countries. That’s an expensive, labor-intensive enterprise in areas with limited resources, making the beans’ continued existence precarious, Krishnan and others say.
Because they can’t save all the coffee, Krishnan and her international team of coffee scientists prioritized four gene banks (three in Africa and one in Costa Rica) in their quest to save wild coffee. Among the immediate needs: Upgrade conditions for existing plants, restock with missing wild species, and enable sharing of data and genetic material—and find an estimated $25 million from industry over the next 25 years to fund it all.
The wild species will be used to develop new, hardier varieties by coffee breeders like Simon Martin Mvuyekure, who is looking for disease- and drought-resistant crops to plant in East Africa. Another dream for some: to create a hybrid with a flavor as divine as the legendary bean that saved Panama’s coffee industry nearly 10 years ago.
Growers there were facing record low prices and selling unprofitable land to developers, when one farm experimented with a wild Ethiopian strain whose seeds had originated at the Costa Rica gene bank. Known as Geisha, its distinctive flowery aroma rated high among tasters and broke all records at auction. It is now the most expensive coffee on Earth.