Scientists Rediscover Climate-Resistant Coffee Plant

The climate crisis doesn’t just pose a danger to lives and ecosystems. It also threatens to take away smaller pleasures, like your morning cup of coffee. 

Experts have long known that hotter temperatures pose a problem for Coffea arabica (Arabica), the species of high-quality coffee that provides the majority of the beans we grind at home or savor in cafes. However, no workable solution has been proposed—until now.

A recently rediscovered coffee species could be the key to keeping those iced coffees coming as the planet warms, a study published last month in Nature Plants concluded.

“To find a coffee species that flourishes at higher temperatures and has an excellent flavor is a once in a lifetime scientific discovery—this species could be essential for the future of high-quality coffee,” study lead author and coffee research leader at the U.K.’s Royal Botanical Gardens at Kew Aaron Davis said in a press release.

Climate and Coffee

While there are 124 species of coffee in existence, 99% of the coffee we drink comes from just two species: Arabica and Coffea canephora (robusta). Arabica, which originated in the highlands of Ethiopia and South Sudan, is both the tastier and more vulnerable of the two. It requires mean annual temperatures of around 66 degrees and is more susceptible to a fungal disease called coffee leaf rust. 

Robusta is more, well, robust. It can grow in the tropical lowlands of Africa at higher mean annual temperatures of around 73 degrees. It is also able to resist some strains of coffee leaf rust. However, it is not considered as flavorful and is more often used to make instant coffee. 

Coffee production is also likely to falter in the future because of both an uptick in severe weather and increased drought, Davis tells Treehugger in an email. 

“The world is still producing plenty of coffee, but those that farm in areas where the conditions are not optimal are already suffering from the impacts of climate change,” Davis says. “As global temperatures increase, this situation will only worsen.”

A Star is Reborn

This is where the new rediscovery comes in. 

In December of 2018, Davis traveled with Jeremy Haggar of the University of Greenwich to Sierra Leone. They were there to try and locate a type of coffee known as C. stenophylla, which had not been observed in the wild since 1954. 

Stenophylla had been grown as a crop species in upper West Africa more than 100 years ago, but had most likely been phased out in favor of robusta, which has a higher yield, Davis explains. With the help of Sierra Leone development specialist Daniel Sarmu, however, the researchers were able to find first a single plant and then an entire population of the “lost” coffee.

Davis, Haggar, and Sarmu published their findings in Frontiers in Plant Science last year, but they still didn’t know if the newly rediscovered plant had any commercial potential. 

First, they had to assess its growing requirements. These proved promising. The plant can grow under similar conditions to robusta, but at a mean temperature of 76.8 degrees. That’s 3.8 degrees higher than robusta and a full 10.8 degrees higher than Arabica. Further, there is some evidence it may be drought resistant. 

But how did it taste? Its flavor had not been described in more than a century. Would it be up to current standards? The “new” coffee was tested twice. 

First, the coffee was sampled in the summer of 2020 by a panel at Union Hand-Roasted Coffee in London and earned a score of 80.25. This is notable because coffee must earn a score of more than 80 to be considered a specialty coffee, and Arabica was previously the only species that had earned this distinction. 

Then, it was tested by 15 experts from major coffee companies and CIRAD, the French Agricultural Research Centre for International Development. Eighty-one percent of the experts thought the new species was in fact Arabica, while 47% did think there was something new about it. They identified flavors including peach, blackcurrant, mandarin, honey, light black tea, jasmine, spice, floral, chocolate, caramel, nuts, and elderflower syrup.

“The sensory analysis of stenophylla reveals a complex and unusual flavor profile that the judges unanimously found worthy of interest,” CIRAD scientist Dr. Delphine Mieulet, who led the tasting, said in the press release. “For me, as a breeder, this new species is full of hope and allows us to imagine a bright future for quality coffee, despite climate change.”

What’s Next?

The taste test doesn’t mean that you will be seeing stenophylla in the coffee aisle in the near future. The species is still rare in the wild, so much so that it is considered vulnerable by the IUCN Red List of Threatened Species. Researchers are now working to protect its wild populations and to plant seeds in Sierra Leone and Reunion Island, off East Africa, in order to further test its potential as a crop. 

Davis says the next steps for his research team are “to better understand its farming requirements and climatic tolerances, find the best performing variants of this species, and assess its market potential and use in plant breeding.”

Even if all of these tests turn out well, stenophylla is not necessarily the only solution to coffee’s climate problem. Rather, it reveals the danger inherent in relying on only two species to provide the world’s commercial supply. 

“We will need to employ other coffee species, to broaden the portfolio of coffee crop types”, Davis explains. 

 Those types would need to meet four key characteristics. 

1. Be able to grow in higher temperatures.
2. Resist drought. 
3. Resist pests and diseases.
4. Taste good.

“Stenophylla ticks at least two of these boxes, and possibly more, which is why it could be important,” Davis says.

However, other species could help boost the coffee crop’s biodiversity as well, including some species of Liberica coffee, some species that are currently farmed on a smaller scale and wild species that are still unknown. 

The discovery of stenophylla isn’t only a potential solution to the problems of coffee drinkers, but also coffee farmers. There are currently more than 100 million people who make their living growing coffee, and this living would be threatened were the global crop to fail. Stenophylla could also offer some of them new opportunities, especially in Sierra Leone where it was first rediscovered. Small scale coffee farmers in that country currently make less than $140 a year from their crops, so the development of a new and notable species in the country could give these farmers a much-needed boost.

“We hope that stenophylla coffee will become a flagship export crop for our beloved Sierra Leone, providing wealth creation for our country’s coffee farmers,” Sarmu said in the press release. “It would be wonderful to see this coffee reinstated as part of our cultural heritage.”