Cool beans? Not quite: Global warming is helping to wipe out coffee in the wild

Aaron Davis, a British botanist, has spent 30 years trekking across forests and farms to chronicle the fate of one plant: coffee.

He has recorded how a warming planet is making it harder to grow coffee in traditional coffee-producing regions, including Ethiopia, the birthplace of the world’s most popular bean, arabica. He has mapped where farmers can grow coffee next: basically upcountry, where it’s cooler. He has gone searching for rare varieties in the wild.

Now, Davis has found that wild coffee, the dozens of varieties that once occurred under forest canopies on at least three continents, is at risk of vanishing forever. Among the world’s 124 coffee species, he and a team of scientists have concluded, 60 percent are at risk of extinction in the wild. Climate change and deforestation are to blame.

It matters because those wild varieties could be crucial for coffee’s survival in the era of global warming. In those plants could lie the genes that scientists need to develop new varieties that can grow on a hotter, drier planet.

Ultimately, Davis said, those wild coffees are vital for the millions of farmers who make a living from coffee, not to mention the many more who rely on caffeine to start their days.

“There are a broad range of traits, which have good potential for addressing specific issues in the future, whether its drought tolerance or disease resistance,” Davis said. “As we lose those coffees, our options diminish.”

Davis and his co-authors published their findings Wednesday in two papers, in Science Advances and Global Change Biology.

Of the 124 known wild species, most are not cultivated or consumed. Two exceptions are arabica, which has been farmed for hundreds of years in East Africa, and robusta, which has gone from the wild to one of the world’s most important commodities. Coffee farmers already face mounting pressure from drought, disease and the vagaries of commodities prices. Addressing those risks requires tapping into the genetic riches of wild varieties.

Wild coffees can be preserved in seed banks or in nationally protected forests. Most are not. Davis’ inventory found that nearly half of all wild coffee species are not held in seed banks, and a third do not grow in national forests.

A 2018 report by the Crop Trust, which runs a global seed bank, also warned of the need to preserve the genetic diversity of coffee, including its wild varieties. Only a handful of gene banks hold coffee trees, the report found, and many of them are hampered by either aging specimens or a lack of adequate funding.

To assess the risks faced by wild coffees, Davis and his colleagues applied a barometer developed by the International Union for Conservation of Nature. Using that index, they found wild arabica, which mainly grows in the forests of Ethiopia, to be particularly vulnerable to the effects of climate change.

If greenhouse gas emissions continue to rise at their current pace, changing climate conditions could move wild arabica from the conservation union’s “near threatened” category to “extinct” by the end of the century.

For Davis, the loss of wild varieties is important not just for plant breeders, farmers and coffee drinkers. The loss of a species also means less food and less shelter. The result, in his view, is a diminished Earth. “Our planet becomes less diverse, less interesting,” he said.