16 January 2019

A high extinction threat for wild coffee could rattle the sector

Many wild coffee species are threatened with extinction. What might this mean for the future of coffee farming? Dr Aaron Davis explains.

Coffee beans with a hand

In the UK we consume an estimated 85 million cups of coffee every day, with the coffee shop trade alone valued at around £10 billion per year

Globally, the various activities connected with coffee production, from farmer to consumer, comprise a huge industry and provides livelihoods for around 100 million people worldwide, most of which are smallholder farmers.

For many key coffee producing countries, coffee exports make up a significant and critically important proportion of their export earnings; for many farmers it's their major source of income. 

With global population increasing, so is the demand for coffee. Can the world’s coffee production keep up with global demand?

For the foreseeable future the answer is yes, with bumper harvests recorded in recent years, and plenty of scope for increasing production in many areas.

If, however, you look at the history of coffee cultivation, it has not been plain sailing.

In recent years there have been some catastrophic problems with coffee production in many major producing countries due to issues such as fungal diseases, pests and drought. 

For more than 150 years, coffee agronomists and other scientists have been working hard to resolve issues concerning production and sustainability, and this work continues to the present day.

One of the main resources for this work, and especially for plant breeding, has been the use of wild plants, particularly those related to crops, which house the genetic resources capable of providing disease and pest resistance, climate resilience, and other useful traits such as improved flavour and quality.

These plants, whether for coffee or other crop plants, are often referred to as crop wild relatives (CWRs).

Coffee farmer in Ethiopia with hands full of soil and a seedling
Coffee farmer in Ethiopia © Emily Garthwaite / Union Coffee.

Arabica coffee falters

If we go back to the middle of the nineteenth century, the world’s coffee came almost exclusively from one species – Arabica coffee (Coffea arabica).

Towards the end of the nineteenth century a major problem appeared in Asia - a fungal disease called coffee leaf rust.

In most circumstances, coffee leaf rust is devastating for coffee production, with the potential to wipe out whole plantations in a very short space of time.

And this is exactly what happened in Asia, all but wiping out Arabica coffee production across the whole coffee growing region within less than 30 years.

The response to this catastrophe was to bring in new, and little-known, species resistant to coffee leaf rust. Liberica coffee (C. liberica), from the northern part of tropical West Africa, was the first candidate to be brought in.

It grew well, produced well, and was quite resistant to coffee leaf, but failed in spectacular fashion as it tastes quite awful.

In 1897 Robusta coffee (C. canephora) was discovered and named as a new species by scientists, although we know that it had already been cultivated on a small scale in coastal West Africa from at least the early 1800s.

Able to grow in warmer conditions, and in many cases being easier to cultivate than Arabica coffee, it was also highly productive, and tasted pretty good, too. Importantly, it was resistant to coffee leaf rust.

From the early 1900s onwards its cultivation spread quickly through the tropical coffee belt, from Africa to the Americas and Asia.

Today, it is cultivated more widely than Arabica coffee and comprises at least 40% of the global trade value for coffee. In just 120 years it has been transformed from a more or less unknown wild plant to a major global commodity!

White flowers
Flowers of Arabica coffee, Aaron Davis © RBG Kew
Red and green berries in the palm of a hand.
Arabica coffee fruits, Ethiopia © Aaron Davis / RBG Kew.

The future for coffee and the use of wild coffee species

History tells us that coffee production is dynamic, in terms of where coffee is grown and also what species we grow.

We now depend on two species, Arabica and Robusta, to provide us with the coffee we drink, but what does the future hold?

The increasing severity of pests and diseases, the loss of suitable space to grow coffee and climate change are all having their impact, putting increasing pressure on coffee farmers.

There are a number of possible solutions to these problems.

Important opportunities are likely to come from the use of wild coffee species, and the incorporation of specific genes from wild plants via breeding.

This may seem fanciful to some, but this is exactly what has happened in the past, as given in the example above for Robusta coffee and numerous examples where we have utilized genes from wild coffee diversity to resolve production issues.

Might we be using previously unused or under-utilized wild coffee species in the future, or the useful genes they contain?

In total there are 124 coffee species, growing wild in tropical Africa, Madagascar, Asia and Australasia, and this wild species gene pool could have considerable potential for the long-term future of coffee farming. 

Extinction risk for the world’s coffee species

With the support of International Union for the Conservation of Nature (IUCN) and Toyota Motor Corporation, Kew’s Plant Assessment Unit is now able to assess the extinction risk of 1,000 plant species each year.

As part of this project, during 2017 and 2018 we had the opportunity to review more than two decades of research on wild coffees, undertaken by Kew scientists and in-country partners, to produce formal IUCN extinction risk assessments for all 124 coffee species. 

The majority of the extinction risk assessments for coffee were undertaken by Helen Chadburn, one of Kew’s unsung heroines of plant conservation. 

Using data gathered from specimens in Kew’s Herbarium (and many others) and information from other researchers on the occurrence of coffee species and the factors that threaten their survival, Helen and her colleagues were able to reveal the bad news: that more than 60% of coffee species are threatened with extinction. 

Further work went on to show that many of the species with the greatest potential for use in coffee crop development are amongst those with the highest extinction risk, and do not have adequate measures in place for effective conservation. 

There are several species we haven’t seen in the wild, or in cultivation, for over 100 years.

Some of these may already be extinct. 

Around 45% of coffee species are not found in living collections or seed banks (germplasm collections), and 30% have no protection in the wild (i.e. do not fall within the boundaries of national parks, wildlife reserves, and other protected areas).

Given the importance of wild coffee species for crop development and long-term sustainability, these are worrying figures. 

An additional extiction risk assessment was carried out by Kew and Ethiopian researchers on Arabica coffee for the first time, with the incorporation of climate change projections.

Kew's Dr Justin Moat lead the work and his analyses showed that wild Arabica is endangered, with its natural population estimated to reduce by up to 50% or more by 2088 due to climate change alone. 

This paints an increasingly worrying picture for many other coffee species if climate change is taken into account in considering their extinction risk.

However, for most other coffee species we don’t have the detailed spatial data required to attempt climate change projections. 

People in forest.
Aaron undertaking research on Arabica coffee in South Sudan. © Emma Sage / Coffee Quality Institute).

Preserving the world’s coffee species

It’s clear from our work that protected areas and germplasm collections require more resources, so that they can incorporate more coffee species and greater coffee genetic diversity, upgrade their facilities and improve management.

This is particularly true for specific African countries (such as Ethiopia, Tanzania, Cameroon and Angola) and Madagascar, which have the highest levels of wild coffee species diversity.

The utilization of wild coffee species can benefit their survival, as species with value are often more obvious priorities for conservation. 

In Ethiopia, coffee farming is being used to preserve the wild populations of Arabica coffee.

The Yayu Forest Project, is a joint venture between Kew, Union Hand-Roasted Coffee in East London, Ethiopian partners, and the coffee farming community of Yayu in south-western Ethiopia.

The project’s model is quite simple: improving coffee quality increases the price paid to the farmers, which improves the income from coffee, and because the coffee is forest-grown there is real incentive to retain the forest and the biodiversity that it contains; the coffee forest production areas surround pristine forest, which includes one of the best remaining refuges for wild Arabica coffee, thus conserving the species in the wild.

Other carefully devised initiatives and interventions might be employed to conserve other coffee species, but overall we need to improve our conservation efforts.

This also extends to all of our wild plant species, and especially those that play a critical role in sustaining the future of our planet and the wellbeing of its inhabitants.

Female coffee farmers
Drying forest coffee, Ethiopia © Alan Schaller / Union Coffee.
Two beans held between fingertips.
Beans of threatened coffee species. Left: Ambongo coffee (C. ambongensis) from Madagascar; right: Arabica coffee (C. arabica) from Ethiopia, Andrew McRobb © RBG Kew

What can coffee drinkers do to help conserve wild species?

Apart from specific projects, such as Yayu, where purchasing a particular coffee provides a business-like model for conservation (known as mainstreaming), it’s still difficult to make transformative change via consumer choice.

This needs to alter, particularly as coffee farming can have both negative and positive environmental impacts. In many places coffee farming is a major cause of deforestation, not necessarily often affecting wild coffee species, but certainly causing significant losses in forest and related biodiversity.

Clearly, we need to do much more with the labelling of coffee products, so that consumers are fully aware of the impact (both positive and negative) of their purchasing choices.

At the moment there are lots of different types of certification but very few factor in forest preservation or details of negative environmental impact. 

Over the last two years coffee prices have been unsustainably low.

This needs to change. It's clear that there needs to be a fair and sustainable process for coffee farmers.

Recent low coffee prices have pushed many farmers into low profitability or losses. Coffee farmers around the world are in many cases the guardians of the sensory (flavour) diversity of cultivated coffees (Arabica and Robusta).

If prices remain low for too long farmers will eventually stop growing coffee, and we will lose much of what makes coffee special.

Plates of coffee beans on a table.
Preparation of coffee in Ethiopia, a native cultural crop that supports 15 million national livelihoods. Image © Jenny Williams / RBG Kew.


This work was supported by the IUCN and Toyota Motor Corporation through the project “The IUCN Red List of Threatened Species and Toyota Motor Corporation” and is one of the products of the Global Coffee Assessment, undertaken by the Plant Assessment Unit (RBG, Kew). Fieldwork in Ethiopia was conducted under the project Building a Climate Resilient Coffee Economy for Ethiopia, within the Strategic Climate Institutions Programme (SCIP) Fund, financed by the governments of the United Kingdom (DFID), Denmark, and Norway. Fieldwork in Africa was supported by the Amar-Franses and Foster-Jenkins Trust and the Bentham-Moxon Trust. 


Davis, A.P., et al. (2019). High extinction risk for wild coffee species and implications for coffee sector sustainability. Science Advances, 5 : eaav3473. Available online

Moat, J., Gole, T.W. & Davis, A.P. (2018). Least concern to endangered: Applying climate change projections profoundly influences the extinction risk assessment for wild Arabica coffee. Gobal Change Biology, 1-14. Available online.

The IUCN Red List - to view the assessments mentioned, search Coffea.

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