Building a climate resilient coffee economy for Ethiopia

Aaron Davis describes how Kew scientists are helping to build a climate resilient coffee economy strategy for Ethiopia via a rigorous assessment of the influence of climate change on coffee-producing areas and wild coffee forests.

Coffee cherries

Growth and development of coffee consumption

Global consumption of coffee has increased significantly over the last decades. It is now believed to be the world’s favourite beverage, with an estimated 500 billion cups consumed each year. In many supermarkets the choice of coffee is bewildering, and even village stores or post offices stock single origin or other speciality coffees. We now have ‘coffee geeks’ and coffee shops employing hip baristas with highly refined and precise brewing methods, using equipment that would not look out of place in a laboratory. Some coffees have more complex tasting notes than wine, such as ‘blueberry cider’, ‘sweet sugared lemon tingle’ or ‘silky milk chocolate’.

The consumer certainly has plenty of choice and overall the standard of the coffee we drink has improved significantly. This is great news for coffee lovers, but do we ever pause to consider where coffee comes from, how it has been produced and how sustainable our daily cup of coffee really is?

Some coffee botany

Coffee comes from species of the coffee genus Coffea, of which there are 124 known species, although we only consume two of these. Arabica coffee (Coffea arabica), which originates from the cool tropical forests of Ethiopia and South Sudan, has an excellent cup profile (aroma, acidity, flavour and balance), natural sweetness and moderate caffeine content. This is the coffee we consume in most high street coffee shops and at home if we use whole bean or ground coffees. The other is robusta (Coffea canephora), which comes from the lowlands of tropical West and Central Africa. This is commonly used to make instant coffee and is sometimes added to espresso blends to improve body and crema, the light brown foam on the top of an espresso. The cup profile of robusta lacks subtlety. It has a distinct ‘woody’ flavour and can have up to four times the amount of caffeine compared with Arabica.

Arabica accounts for around 65% of global production and robusta 35%, although the proportion of robusta in the market has recently increased due to cheaper production costs.

Coffee trees produce red, or sometimes yellow, fruits about the size of a small cherry. Inside the fruit are two seeds embedded in a soft, sweet, sticky pulp known in botanical terminology as the mesocarp, and each seed is encased in a crispy coat known as the parchment (or endocarp). The skin (or epicarp) pulp and parchment are removed using a range of different methods, leaving the green bean (the seed) which, in terms of farming, is the finished product.

The green beans are exported to the country of consumption and then roasted, an activity involving science and art, to produce brown coffee beans. The roaster applies what he considers to be the correct roasting profile (the scientific method) in order to best suit not only the coffee type but also the consumer’s preference, although there is often (or exclusively) an artisanal element based on many years of roasting experience. Once roasted the coffee is left to ‘settle’ for a day or so, and then consumed within a few weeks. 

The value chain: from crop to cup

The value chain is the series of activities that a specific industry performs in order to deliver a product or service for the market, with value built at each step. The farming parts of the coffee value chain alone are extremely labour intensive, particularly where coffee is hand-picked and hand-sorted which is the norm for the majority of producers. Most of the world’s coffee is grown by smallholder farmers, often each with less than one hectare of land, which is why it takes an estimated 25 million coffee-farming families to produce the world’s coffee. That seems like a lot of people, but the world consumes a lot of coffee: some 90 million bags per year, with each bag weighing around 60 kg.

In terms of monetary value, coffee is the world’s most important agricultural commodity, second only to oil as the world’s most-traded commodity. After exportation to consumer countries, further value is added to the commodity via those parts of the value-chain that take the crop from green bean to cup. They includes roasters, manufacturers, coffee shops and supermarkets or the revenues generated after farming in the coffee producing countries themselves. For example, it is estimated that Ethiopia, Africa’s largest coffee producer, consumes 50% of the coffee it grows.


So this is all good news. Coffee production is providing producing countries and importing countries with a commodity that supports livelihoods and commerce. Yes...but there are problems. These include market volatility, pests and diseases, adverse weather events and increasing production costs, leading to failing crops and low revenues for the farmer and sustainability issues for coffee providers in general.

There are several causal agents behind the above problems but climate change is the most prevalent and worrying. Indeed, it has been argued that the extreme wet weather of recent years in Central America, which led to the severe episode of the immensely damaging fungal pathogen coffee leaf rust (CLR), and the last two droughts in Brazil, were driven, or at least exacerbated, by long-term global climate change. These events have resulted in huge, multi-million losses in revenue. Convincing scientific evidence shows that increases in average temperatures over the long term have caused coffee pests to migrate to new areas, and that the severity of infestations has increased.

Climate change and coffee production in Ethiopia 

There is good reason for focusing on Ethiopia, as it is the world’s third largest producer/exporter of Arabica coffee. It is home to at least 95% of the genetic resources for the species. The genetic diversity of Arabica coffee outside Ethiopia, in farms and plantations around the world, is woefully inadequate.

Coffee is the backbone of the Ethiopian economy, providing more than 30% of the country’s export earnings, totalling around $350 million. It is estimated that 25% of the population, some 20 million people, depend directly or indirectly on coffee for its livelihood; in SW Ethiopia coffee is the main provider of household income. Ethiopia’s Poverty Reduction Strategy Paper and Growth and Transformation Plan (2010/11–2014/15) highlights that increasing coffee productivity, while conserving biodiversity and genetic resources, will play an important role in Ethiopia reaching the first Millennium development goal (eradicate extreme poverty and hunger). However, coffee production in Ethiopia faces numerous challenges in an uncertain climatic future.

In 2012, we published the study The Impact of Climate Change on Indigenous Arabica Coffee (Coffea arabica): Predicting Future Trends and Identifying Priorities, which investigated the potential influence of climate change on wild Arabica coffee in Ethiopia and South Sudan, the only places on Earth where this species grows naturally. 

The computer modelling study indicated a severely negative impact on wild coffee forests, with predictions of 65% to almost 100% loss of suitable localities for the survival of the species. As these forests occur within the same bioclimatic areas as most of the coffee produced in Ethiopia, the logical assumption was that Ethiopia coffee production would be also severely negatively affected.

In November 2013, we embarked on the collaborative project Building a climate resilient coffee economy for Ethiopia, under the Strategic Climate Institutions Programme (SCIP). The SCIP Fund is a DFID/Norway/Denmark-backed fund designed to build Ethiopia’s capacity to cope with climate change across the public, private and civil society sectors and to respond to the challenges of transitioning to a climate resilient green economy.

The aim of the project is to provide a climate resilient coffee economy strategy for Ethiopia via a rigorous assessment of the influence of climate change on coffee producing areas and wild coffee forests. The climate change assessment is based on a combination of activities, including high resolution mapping, climate change modelling, extensive ground-truthing, farmer interviews and climate monitoring.

After more than 10,000km of travel across Ethiopia, visiting coffee production areas and wild coffee forests, we have now gathered sufficient data to verify the satellite mapping of forest coffee production and to run the computer modelling for those areas that cannot be easily viewed from space, such as coffee gardens (small-scale production, of often less than 20 trees). The data analyses are now well underway, including the review of 24 climate change models and the mapping of coffee forests at less than 30 m resolution. Once finalized, these analyses will be compared with information gathered from farmers and producers, existing weather station data and climate monitoring equipment that we have placed within coffee farms across Ethiopia.

Later this year we will present our findings to key stakeholders in Ethiopia to gather their considerable expertise and expert opinion. The strategy developed during this and other workshops, in combination with other project outputs, will provide the understanding and awareness required to best sustain the Ethiopian coffee industry in relation to climate change and land-use, and identify what is needed to ensure resilience. In short, we will identify what to do, when, where and why.


Davis, A. P., Gole, T. W. Baena, S. & Moat, J. (2012). The impact of climate change on natural populations of Arabica coffee: predicting future trends and identifying priorities. PLoS ONE 7(11): .e47981. Available online

Davis, A. P., Tosh, J., Ruch, N. & Fay, M. F. (2011). Growing coffee: Psilanthus (Rubiaceae) subsumed on the basis of molecular and morphological data: implications for the size, morphology, distribution and evolutionary history of CoffeaBotanical Journal of the Linnean Society 167: 357–377.Available online

Davis, A.P., Chester, M., Maurin, O. & Fay, M.F. (2007). Searching for the relatives of Coffea (Rubiaceae, Ixoroideae): the circumscription and phylogeny of Coffeeae based on plastid sequence data and morphology. American Journal of Botany 94: 313–329. Available online

Davis, A. P., Govaerts, R., Bridson, D. M. & Stoffelen, P. (2006). An annotated taxonomic conspectus of the genus Coffea (Rubiaceae). Botanical Journal of the Linnean Society 152: 465–512. Available online

Jaramillo, J., Muchugu, E., Vega, F.E., Davis, A.P., Borgemeister, C. & Chabi-Olaye A. (2011). Some like it hot: the influence and implications of climate change on coffee berry borer (Hypothenemus hampei) and coffee production in East Africa. PLoS ONE 6: e24528. Available online.