Monday Article #21: Discovery of climate-resistant coffee
Dear Coffee lovers around the world,
The first sip of coffee every morning gives us the smallest pleasure as an energy boost before we start our day. Enjoying our favourite morning brew, we probably aren’t thinking about the threat towards coffee plants! Do you know that coffee plants come under pressure from the climate crisis, sustaining this habit will be increasingly challenging. Recently, a new study provided a glimmer of hope: a climate-resistant alternative coffee plant just as tasty as arabica.
Climate and coffee
Coffee farming is under threat due to various challenges at the production (farm) level, including the prevalence and severity of disease and pests and climate change. These factors indicate the urge to substantially diversify the coffee crop portfolio to ensure resilience and sustainability.
Among 124 species of coffees, the global coffee trade lies on two specific species, namely Arabica (Coffea arabica) and Robusta (Coffea canephora) and 99% of the coffee we drink comes from just these two species. Arabica, originated in the highlands of Ethiopia and South Sudan are known to be a cool-tropical plant. Within the context of long-term climate change, it has been argued that Arabica alone does not have the potential to attain the level of climate resiliency required for adaptation under existing climate change projections. For Arabica, the indigenous range of its cultivation does not show any evidence of climate partitioning or useful climate resilience attributes.
Robusta coffee is a low-elevation species, occurring naturally across much of wet-tropical Africa and is adapted to higher mean (annual) temperatures of 24–26 °C. It is also resistant to the prevalent strains of coffee leaf rust, a serious constraint for Arabica farming in Central and South America. For these reasons, robusta is often used as an alternative species for Arabica under a scenario of increasing temperatures and erratic rainfall. However, robusta may require as much or more rainfall (soil moisture) as Arabica, relative to other climate variables and could be more temperature sensitive than previously supposed.
The botanists and researchers have mentioned that these factors could likely cause coffee production to falter in the future because of severe weather and increased drought. 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. As global temperatures increase, this situation will only worsen.
The future coffee
Experts believe that the newly rediscovered Stenophylla could be a game changer in terms of breeding resilient crops and providing a “superior flavour”. The plant was re-discovered growing wild in Sierra Leone, where it was historically grown as a coffee crop about a century ago. However, given their age and context, these claims for this species have not been universal. In its native habitat, stenophylla is a species of low-elevation, hot-tropical environments. It is also reported to be drought tolerant and have partial resistance to coffee leaf rust. The seeds of stenophylla are about the same size or slightly smaller than Arabica.
Figure above shows Coffea Stenophylla plant
But how did it taste? Several historical references indicate that this species has an excellent taste, as good as ‘best mocha’ and possibly superior to all other coffees. Its flavour had not been described in more than a century. Would it be up to current standards? The “new” coffee was tested twice.
The first test was carried out in the summer of 2020, in which the coffee was sampled 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.
Later, 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 flavours including peach, blackcurrant, mandarin, honey, light black tea, jasmine, spice, floral, chocolate, caramel, nuts, and elderflower syrup.
The scientists of CIRAD mentioned that, the sensory analysis of stenophylla reveals a complex and unusual flavour profile that they found unanimously worthy of interest. However, the taste test will not be the only criteria to consider as the species is still rare in the wild. 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.
To better understand its farming requirements and climatic tolerances, the best performing variants of this species are needed to 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. Scientists have explained that, we will need to employ other coffee species, to broaden the portfolio of coffee crop types.
Davis, A. P., Gargiulo, R., Fay, M. F., Sarmu, D., & Haggar, J. (2020). Lost and found: Coffea stenophylla and C. affinis, the forgotten coffee crop species of West Africa. Frontiers in Plant Science, 11, 616.
Davis, A. P., Mieulet, D., Moat, J., Sarmu, D., & Haggar, J. (2021). Arabica-like flavour in a heat-tolerant wild coffee species. Nature Plants, 7(4), 413-418.
This article is prepared by: Tanessri Muni Peragas