Robusta is here to stay – but it cannot save the future of coffee

robusta coffee climate change resilience
  • The land available to grow high-quality arabica is expected to predicted to halve by 2050
  • Robusta is often posited as a long-term solution to prop up supply
  • Researchers found that it doesn’t offer the level of climate resilience that many believe

YOU’VE ALMOST certainly heard it before: robusta coffee is a more resilient species than arabica. It can withstand higher temperatures. It is less susceptible to pests and disease outbreaks. And it doesn’t suffer from nearly the same level of cherry “run off” where cherries fall from trees due to heavy rainfall and wind.

This has made it a subject of growing fascination among coffee professionals and scientists. Climate change is expected to wipe out half the land available to grow high-quality arabica coffee within the next 25 years. In 2019, it was placed on the IUCN Red List as an Endangered species, largely due to climate change projections, and, according to a study by London’s Royal Botanic Gardens, wild arabica could vanish completely by 2080.

With solutions to global warming few and far between, the extensive cultivation of a more climate-resilient species is generally presented as the only realistic way forward. And robusta, cultivated and processed in such a way that it tastes just as good as arabica, is the best answer we have.

Unfortunately, a team of researchers from the Centre for Applied Climate Sciences at the University of Southern Queensland have proved otherwise. Looking to explore long-held assumptions about robusta coffee’s optimal temperature bracket, they found that the 22-30°C range was not only taken from just one area in the Congo – it was more than 400 years old.

“The values were based on botanical expeditions to the Congo in the 16th century,” says Jarrod Kath, one of the study’s authors. “But this value permeated through the literature we observed. As long as you grew robusta in that climatic range, it was assumed your yields would be optimal. We thought we would see if that was the case.”

The team used the largest robusta data set in the world – ten years of yield observations from 798 farms across South East Asia, coupled with high-resolution precipitation and temperature data – to quantify the optimum production range. Their results came as something of a surprise. They found that robusta has an optimal temperature below 20.5°C – over 9°C under the top of the assumed range.

“We checked it every which way and no matter how we analysed it, we kept getting this huge discrepancy in temperature,” Jarrod says. “We’d essentially taken it for granted that it was the most valid data point to rest our decisions and actions on. But we didn’t find that at all. I would even argue that our analysis is conservative.”

What does this mean for the future of coffee?

When the pioneering study into robusta was published in March 2020, it was picked up by a number of media outlets, such as Sprudge and Daily Coffee News.

But with the outbreak of Covid-19 taking centre stage, what should have been a groundbreaking revelation was drowned out by concerns over logistics, social distancing, and how to stop the devastating novel virus from spreading.

Now, with the pandemic behind us, the focus is back on the potential of robusta to dig the world out of a different crisis: rising costs of production. Specialty – or “fine” – robusta has been posited as a solution thanks to its lower cost compared to arabica. A number of specialty coffee roasters have introduced robusta-arabica blends, or even tried to push a standalone single origin.

But in the same way that assumptions about the optimal temperature range were off, Jarrod says that beliefs about uprooting arabica and simply planting robusta in its place may also be misguided.

“Our findings challenge the ease with which we could replace arabica with robusta,” he says. “Robusta might survive in very high temperatures and more difficult climatic conditions, but whether or not you will get a yield sufficient to justify the costs of growing it is an open question. Cost of production relative to your profit is a big thing.”

He notes that the areas in which arabica currently grows might not be as suitable as assumed. Convincing producers who have grown arabica for decades to suddenly start growing a different species could also be a tough sell.

“It might be socially difficult,” Jarrod says. “Maybe the idea of ripping up arabica and planting robusta won’t go down too well with the people who live there. These are important details that are not well known. I think a global-level study on what the transition might look like is really important. But I wouldn’t put all my eggs in the robusta basket.”

coffee farmer picking ripe cherries

Towards a better solution

The impact that climate change will have on coffee production isn’t just something that scientists in places like Kew Gardens are sat around making predictions about. For those in coffee-growing regions, its devastating consequences are becoming clearer with each season.

Rising temperatures and erratic rainfall have already severely reduced harvests in regions at lower elevations and potentially exacerbated problems, such as coffee leaf rust.

For example, a catastrophic outbreak of the disease caused arabica production in Central America to drop by 17% between 2011 and 2014, which had a long-lasting economic impact on the region. Researchers believe that among the culprits were decreased diurnal temperature and earlier onset of the rainy season as a result of climate change.

The notion that farm owners can simply uproot arabica and plant robusta – or other more resilient species – as a catch-all solution is fraught with uncertainty. What is becoming increasingly obvious, however, is that of the 25 million coffee farmers whose livelihoods stand to be affected, the percentage of those on lower incomes will be worst hit.

“There’s a belief richer farmers will be fine and able to adapt, while the poorer farmers who can’t move their farms to higher elevations or change varieties or install fancy irrigation will suffer,” Jarrod says. “It is a really bad outcome for a lot of the world’s coffee farmers.

“Even if there are solutions on the horizon for dealing with climate change in terms of coffee production, it doesn’t mean we shouldn’t be concerned about the impact it has both socially and economically for millions of coffee farmers.”

A better approach is to start mapping out how each region – and even each farm within that region – can deal with inevitable temperature rises, whether that means transitioning to robusta or diversifying crops, such as by introducing cacao or avocados. That way, each one at least has a roadmap for dealing with expected changes and can ease into the process, rather than facing sudden disruption.

The question then turns to when this should happen. We know that by 2050 it will be too late – but demanding that farmers carry out trials for something that will likely happen in the future is unrealistic, particularly with the pressures of rising costs of production.

Unfortunately, when it comes to climate change, time is precious. And if robusta isn’t going to be the coffee industry’s silver bullet then acting fast to find alternatives and ensuring it works for coffee farmers too, is of the utmost importance. As Jarrod says, realising that what could have been done should have taken place 20 years ago helps no one.