To survive climate change, coffee must adopt resistant beans

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The research team’s task was as big as the mountains they climbed in December 2018. Your mission? Find a kind of cafe not seen in Sierra Leone for nearly 70 years.

The species, although lost in the wild, survived in textbooks. Daniel Sarmu, a local researcher on the team, researched “field to field” for four years. If some peculiar plant caught his eye, he would take a sample, hoping it was the lost species. But every genetic test came back negative; the search continued.

Until the expedition in 2018, when researchers found a plant of Coffea stenophylla in the hills of Kasewe, largely deforested.

The moment was bittersweet. To regenerate the elusive species, they needed to cross this plant with another – but a second stenophylla plant was not in sight. A few days later, they ventured into Kambui Hills. After just an hour of walking – a drop in the bucket compared to Sarmu’s four-year research – they discovered 20 plants. At every stage of life, stenophylla was blooming: seedlings, seedlings and trees.

“So we knew we had something to build on in terms of rescuing the species,” recalls Jeremy Haggar, a researcher on the team and a professor of agroecology at the University of Greenwich.

There are 124 species of coffee, but most coffee drinkers are only familiar with two: Arabica and Robusta. Arabica accounts for 60% of the coffee sold annually, while robusta accounts for 40%. According to the US Department of Agriculture, about 165 million bags of coffee are produced worldwide each year. But for the coffee industry to adjust to a warmer climate, farmers will need to grow several species of coffee in addition to those commonly enjoyed today. Species with remarkable climate resilience, flavor and scalability – such as stenophylla – are prime candidates.

Climate change has already had repercussions on the coffee sector. Brazil, the supplier of a third of the world’s coffee, recently experienced its worst frost in at least 40 years, pushing prices up. By 2050, demand for coffee is expected to triple – but the way coffee has been produced up to this point cannot scale to meet this challenge.

“Even if you have these two species that cover a range of climatic conditions, it’s really not going to be enough in terms of adapting to climate change,” explained Aaron Davis, lead researcher on the study and senior research leader at the Royal Botanic Gardens, Kew.

Increasing coffee production is like building on a fragile house of cards – Arabica growing hotspots will get too hot to harvest in the coming decades, lowering yields on the key species we depend on today. As temperatures rise, arabica can also lose its flavor quality historically lauded by specialty coffee circles.

“If we were talking about this 10 years ago, they would say, ‘Let’s find a more weather-resistant arabica,’” Davis said. However, developing a climate-resilient arabica requires drastic measures such as breeding or genome editing. “We’ve done a lot of work in Ethiopia – we’ve researched a lot of wild populations, a lot of cultivated plants – and arabica is really fixed in its niche. It doesn’t have the necessary variation in its climate plasticity to really deal with climate change.”

Stenophylla, the species recently rediscovered in Sierra Leone, can withstand heat that arabica cannot, growing in temperatures up to 11 degrees Fahrenheit higher. Since its rediscovery, scientists have been investigating how to accelerate its growth and increase its yield. While stenophylla is far from ready for export, progress is steady.

Stenophylla’s potential excited Sierra Leone residents, including Hannah Tarawally, a 28-year-old self-taught coffee roaster. Coffee production slowed after her country’s civil war ended in 2002. Determined to reconnect farmers to coffee markets, Tarawally founded the Freetown-based roaster Coffee Couriers, one of Sierra Leone’s first dedicated coffee shops.

Tarawally roasts a blend of robusta and arabica every two weeks. Stenophylla is not yet available to local roasters, but when it is, it will transform Tarawally’s line of work. After the struggle to revitalize local coffee production after the war, Tarawally considered stenophylla a “savior” for his community.

“It’s going to make our country’s economy grow, so we’re very excited,” Tarawally shared.

But weather-resistant coffee only becomes a scalable solution if its flavor is so exceptional that it catapults demand. And when that happens, it creates opportunities on the ground where the coffee is roasted. Tarawally expects demand for the new bean to increase due to its unique flavor.

Stenophylla balances fruity and floral flavors with hints of peach, black currant, elderflower syrup and jasmine. The Specialty Coffee Association rates coffees on a 100-point scale; those that rise above 80 points are among the highest positions for specialty coffees. Stenophylla scored 80.25 points, alluding to its prospect of being embraced by global markets. And if it is, Tarawally hopes to “create more jobs for our young people, especially women” to meet the growing demand.

Another key bean for coffee’s climate adaptation is the one that’s in rotation now but has historically been underrated: robusta.

In the past, robusta’s heavy oak and tobacco flavors have excluded the bean from specialty coffee spaces, but its climate potential is creating opportunities to overturn this deeply ingrained perception.

Despite its sensitivity to drought, robusta can tolerate higher temperatures than arabica. And unlike arabica, robusta is resistant to coffee rust, a fungal-induced disease that has caused coffee production to plummet globally for 150 years. The fungus’ spores, brown like rust, cover the tops of coffee leaves, blocking sunlight vital to their growth.

Robusta’s potential caught the attention of businesswoman Sahra Nguyen, 35, who sells single-origin robusta through Nguyen Coffee Supply, a company she founded in 2018.

“When I was starting out, I really felt like I was going against the whole industry because the whole industry was very, very explicit and open about championing this narrative of ‘Arabica is superior, robusta is inferior,’” Nguyen said.

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Robusta is the tried and true bean from Vietnam, which produces around 20% of the world’s coffee supply, totaling 30 million bags. Only 3 million of these bags are robust.

Nguyen Coffee Supply is the first Vietnamese specialty coffee company in the United States, and from the beginning, Nguyen has expanded representation to Vietnamese coffee growers. At the 2019 New York coffee convention, Nguyen Coffee Supply debuted Truegrit, their 100% single-origin robusta. They were the only roasters to do so.

“Probably 95 percent of the people who came to us said, ‘I’ve never actually tried a single-origin robusta,’” Nguyen said. Even the self-proclaimed “coffee snobs” confessed to Nguyen that they never knew robusta could taste this way.

His glowing reviews broke the industry’s long narrative against robusta and signaled its potential to become a bigger share of the coffee market.

Haggar is optimistic that several beans will recalibrate the coffee climate equation.

“I hope we end up with a more diverse supply of coffees of four or five different species,” said Haggar, the researcher. “Which we hope will make coffee consumption more interesting – but it also means that we will have different sources of resilience to a changing climate.”

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