A major new literature review challenges the popular assumption that robusta offers a climate-resilient solution for sustaining global coffee production as climate change continues to disrupt the arabica landscape.
Led by Aaron Davis of Royal Botanic Gardens, Kew, alongside Akshay Dashrath of SICC Labs in India and Kew researcher Justin Moat, the review states that “climate resiliency claims for farmed robusta are misguided.”
The analysis argues that major robusta-producing regions in Vietnam, Brazil and India lack the natural climate conditions required for rain-fed robusta, leading to substantial reliance on irrigation.
The authors wrote that extensive irrigation, low tree-shade cover and high synthetic fertilizer use are “at odds with aspirations for ecosystem and biodiversity stewardship, and counter to goals for a low carbon economy.”
The open-access review was published Aug. 27 in the journal Sustainable Development.
Wild Robusta Likes Wetter Earth
The review examined more than a century of research while adding a new analysis of water availability around wild robusta populations in Africa.
Wild robusta evolved in warm parts of tropical Africa where soil water is generally available for most of the year, whether through rainfall, rivers, wetlands, groundwater or high water tables. The analysis found that wild robusta was more common in landscapes where rivers, wetlands, groundwater or high water tables provided extra moisture beyond rainfall alone.
That reality may be at odds with climate-suitability models based mainly on temperature and rainfall, which can mistake irrigated farms or naturally wet sites for evidence that robusta can thrive under drier conditions, the analysis claims.
“We contest that this proposition is not supported by scientific evidence,” the authors wrote of the idea that robusta, as currently cultivated, offers a straightforward way to sustain global coffee production under climate change.
Global Production Pressure Mounting
The implications are significant. Robusta now accounts for roughly 43% of global coffee trade, according to figures cited in the paper, while Brazil and Vietnam together provide about 65% of robusta exports. In northern Espírito Santo, Brazil’s most important robusta-producing state, approximately 90% of the crop is irrigated.
The pressures are especially visible in Vietnam’s Central Highlands, where DCN recently reported on the environmental costs of the country’s robusta boom.
The authors of the new analysis are not arguing that the coffee industry should abandon robusta. Instead, they call for expansion in places that better match the species’ natural water and temperature requirements, alongside changes in cultivation practices and climate-focused crop development.
Beyond Arabica and Robusta
It should be noted that Davis has been a prominent researcher of coffee species beyond arabica and robusta as coffee production continues to face threats from climate change and lack of genetic diversity.
Kew researchers produced a study last year that established liberica and excelsa as genetically distinct species, with potential implications for commercial cultivation. Earlier this year, a Kew research team led by Davis proposed the name Coffea × libex for hybrids between liberica and excelsa.
The authors of the new paper say much more detailed climate mapping will be needed to identify where rain-fed robusta can sustainably expand.
The research was funded by the Calleva Foundation and the Amar-Franses Foster-Jenkins Trust in the UK. The authors declared no conflicts of interest.
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Nick Brown
Nick Brown is the editor of Daily Coffee News by Roast Magazine.
