A forest nursery for coffee plants in Ethiopia.Credit: Emily Garthwaite

Most of the world’s wild coffee species have a high chance of going extinct in the next several decades due to more frequent and lengthy droughts, loss of forests and the spread of deadly pests, according to a study1 published on 16 January in Science Advances.

The findings signal a potential threat to the multibillion-dollar coffee industry that’s dominated by two varieties — arabica (Coffea arabica) and robusta (Coffea canephora) beans. Arabica is susceptible to high temperatures, whereas robusta is sensitive to dry soils. But the genetic diversity within some of the 124 wild species could help breeders to boost the viability of commercial plants in the face of a changing climate.

“A number of coffee species have traits that allow them to grow in hostile and drier conditions,” says study co-author Aaron Davis, a coffee researcher at the Royal Botanic Gardens, Kew, in London. “But if you start losing species, you start losing options.”

Evaluating risks

Davis and his colleagues spent years cataloguing preserved and wild coffee-plant specimens from around the world, including from remote forests in Africa, Madagascar and Mauritius. It took them two decades to gather enough information on the distribution of wild species and the threats that they face in order to evaluate the extinction risk of each species. The team also searched for﻿ any potentially useful traits in the plants, including disease resistance, caffeine content and drought tolerance.

Using criteria from the International Union for Conservation of Nature, the team found that 60% of all coffee species are at high risk of extinction.

Beans of the threatened ambongo (left) and arabica species in Madagascar. Credit: RGB, Kew

The numbers, according to Alan Andrade, an agricultural plant scientist at the state-owned Brazilian Agricultural Research Corporation in Minas Gerais, are a warning for the entire coffee community. “Imagine how many flavours and aromas [remain] to be uncovered,” he says. “Imagine how many genetic traits still unknown might be the solution for future problems.”

Paper protections

About 72% of coffee species, including wild arabica coffee, grow within protected areas. But many of these places are considered ‘paper parks’ with lax enforcement, says Eimear Nic Lughadha, a plant scientist at Kew and co-author of the study. Protected area status won’t be enough to save these species from extinction because deforestation and climate change can undermine their populations.

Maintaining coffee’s genetic diversity outside its natural habitat is challenging. Unlike many crops, coffee seeds can’t be stored using conventional methods, which maintain harvests under low-moisture and low-temperature conditions. The most advanced techniques, such as keeping seeds at freezing temperatures or using chemical compounds to slow the growth of the plants, are too expensive to use on wild species.

Living collections that attempt to safeguard wild-coffee varieties in the form of seed or plant banks face their own set of threats. The most complete collection of coffee diversity resides in four gene banks comprised of full-grown trees. But these protected locations are underfunded, lack skilled personnel or are threatened by deforestation and pests, according to a 2018 report by the Crop Trust, an organization that works to preserve crop diversity in Bonn, Germany.

Coffee's future

But places such as Ethiopia, where about one-quarter of the population relies on coffee-related activities for their livelihood, are exploring potential solutions to some of these issues. These include splitting wild arabica forests into closely monitored conservation areas and zones where people can farm and produce coffee, honey and spices.

“Coffee is the major commodity crop for African countries that produce it, and the local communities and governments have good reasons to conserve it,” says Tadesse Gole, an ecologist at the Environment, Climate Change and Coffee Forest Forum in Addis Ababa, and co-author of a study2 published on 16 January that predicted wild populations of arabica coffee could decline by 50% by 2088 due to climate change.

But the burden of preserving these species shouldn’t be borne by African nations alone. If the world benefits, Davis says, it’s something that everybody should contribute to.

“If it weren’t for those wild plants, we wouldn’t be drinking coffee,” says Davis. “And if we stop preserving them now, generations to come may not be enjoying coffee in the way that we do today.”