A study conducted by scientists at the Royal Botanic Gardens, Kew (UK), in collaboration with scientists in Ethiopia, reports that climate change alone could lead to the extinction of wild Arabica coffee (Coffea arabica) well before the end of this century. Wild Arabica is considered important for the sustainability of the coffee industry due to its considerable genetic diversity. The Arabicas grown in the world's coffee plantations are from very limited genetic stock and are unlikely to have the flexibility required to cope with climate change and other threats, such as pests and diseases. In Ethiopia, the largest producer of coffee in Africa, climate change will also have a negative influence on coffee production. The climate sensitivity of Arabica is confirmed, supporting the widely reported assumption that climate change will have a damaging impact on commercial coffee production worldwide. These are worrying prospects for the world's favourite beverage – the second most traded commodity after oil, and one crucial to the economies of several countries. The research is published in PLOS ONE on 7 November 2012.
The study, which uses computer modelling, represents the first of its kind for wild Arabica coffee. In fact, modelling the influence of climate change on naturally occuring populations of any coffee species has never been undertaken. Surprisingly, even studies on plantation coffee have been limited, despite the concerns of farmers and other industry stakeholders.
The researchers used field study and 'museum' data (including herbarium specimens) to run bioclimatic models for wild Arabica coffee, in order to deduce the actual (recorded) and predicted geographical distribution for the species. The distribution was then modelled through time until 2080, based on the Hadley Centre Coupled Model, version 3 (HadCM3), a leading model used in climate change research, and the only one available that covered the desired time intervals, for several emission scenarios, at the resolution required (1 km). Three different emission scenarios over three time intervals (2020, 2050, 2080) were used. The models showed a profoundly negative influence on the number and extent of wild Arabica populations.
Two main types of analysis were performed: a locality analysis and an area analysis. In the locality analysis the most favourable outcome is a c. 65% reduction in the number of pre-existing bioclimatically suitable localities, and at the worst, an almost 100% (99.7%) reduction, by 2080. In the area analysis the most favourable outcome is a 38% reduction, and the least favourable a c. 90% reduction, by 2080. Bioclimatic suitability refers to the combination of climatic variables that are necessary for the health and survival of a species: loss of optimum bioclimatic suitability places natural populations under severe environmental stress, leading to a high risk of extinction. This study assesses the survival of Arabica, rather than productivity or beverage quality, under the influence of accelerated climate change. There are other studies showing that the productivity (yield of coffee beans) and beverage quality (e.g. taste) of Arabica are tightly linked to climatic variability, and are strongly influenced by natural climatic fluctuations.
Of the two analyses undertaken, the locality analysis is regarded by the authors as the most pragmatic and informative. The predicted reduction in the number of Arabica localities, between 65% and 99.7%, can be taken as a general assessment of the species' survival as a whole, given the scope and coverage of the data and analyses used in the study. However, the predictions are regarded as 'conservative', as the modelling does not factor in the large-scale deforestation that has occurred in the highland forests of Ethiopia and South Sudan (the natural home of Arabica coffee). Moreover, because of the lack of suitable data, the models assume intact natural vegetation, whereas the highland forests of Ethiopia and South Sudan are highly fragmented due to deforestation. Other factors, such as pests and diseases, changes in flowering times, and perhaps a reduction in the number of birds (which disperse the coffee seeds), are not included in the modelling, and these are likely to have a compounding negative influence.
A visit to South Sudan (Boma Plateau) in April 2012 provided an opportunity to test the modelling predictions via on-the-ground observation. On comparing these observations with a study on Arabica made on the Boma Plateau in 1941, it was clear that not all of the environmental stress evident could be attributed to deforestation or agriculture over the 70 year period. The modelling predicted that Arabica could be extinct in these forests by the year 2020, due to climate change, and this appears to be realistic given the poor health (lack of seedlings, loss of mature Arabica specimens, low frequency of flowering and fruiting) of the remaining populations observed in 2012.
The outcome of climate change in Ethiopia for cultivated Arabica, the only coffee grown in the country, is also assumed to be profoundly negative, as natural populations, forest coffee (semi-domesticated) and some plantations occur in the same general bioclimatic area as indigenous Arabica. Generally the results of the study indicate that Arabica is a climate sensitive species, which supports previously recorded data, various reports, and anecdotal information from coffee farmers. The logical conclusion is that Arabica coffee production is, and will continue to be, strongly influenced by accelerated climate change, and that in most cases the outcome will be negative for the coffee industry. Optimum cultivation conditions are likely to become increasingly difficult to achieve in many pre-existing coffee growing areas, leading to a reduction in productivity, increased and intensified management (such as the use of irrigation), and crop failure (some areas becoming unsuitable for Arabica cultivation). Despite a recent dip, coffee prices are still the highest they have been for some 30 years, due to a combination of high demand and poor harvests. It is perceived by various stakeholders that some of the poor harvests are due to changed climate conditions, thus linking price increases to climate change.
It is hoped that the study will form the basis for developing strategies for the survival of Arabica in the wild. The study identifies a number of core sites, which might be able to sustain wild populations of Arabica throughout this century, serving as long-term in situ storehouses for coffee genetic resources. In many areas of Ethiopia loss of habitat due to deforestation might pose a more serious threat to the survival of Arabica, although it is now clear that even if a forest area is well protected, climate change alone could lead to extinction in certain locations. The study also identifies populations that require immediate conservation action, including collection and storage at more favourable sites (for example in seed banks and living collections).
Aaron Davis, Head of Coffee Research at the Royal Botanic Gardens, Kew, says, "Coffee plays an important role in supporting livelihoods and generating income, and has become part of our modern society and culture. The extinction of Arabica coffee is a startling and worrying prospect. However, the objective of the study was not to provide scaremonger predictions for the demise of Arabica in the wild. The scale of the predictions is certainly cause for concern, but should be seen more as a baseline, from which we can more fully assess what actions are required."
Tadesse Woldemariam Gole, from the Environment and Coffee Forest Forum in Ethiopia, says, "As part of a future-proofing exercise for the long-term sustainability of Arabica production it is essential that the reserves established in Ethiopia to conserve Arabica genetic resources are appropriately funded and carefully managed."
Justin Moat, Head of Spatial Information Science at the Royal Botanic Gardens, Kew, says, "The worst case scenario, as drawn from our analyses, is that wild Arabica could be extinct by 2080. This should alert decision makers to the fragility of the species.
"Our aim is to develop and apply these analyses to other important and threatened plants, on a routine basis. There is an immense amount of information held in museum collections around the world, such as Kew, and we have only just started to unlock their potential for assessing some of society's most pressing issues."
Aaron Davis, Head of Coffee Research at the Royal Botanic Gardens,Kew, is available for interview. Kew's GIS experts, Justin Moat and Steve Bachman, are available for interview about the technical aspects of the modelling. Please contact the RBG Kew press office on pr@kew.org / + 44 (0)20 8332 5607 / +44 (0)7881 953 420
The study was co-authored by: Aaron P. Davis (RBG Kew), Susana Baena (RBG Kew), Justin Moat (RBG Kew), and Tadesse Woldemariam Gole (Environment and Coffee Forest Forum)
The paper is available from http://dx.plos.org/10.1371/journal.pone.0047981 DOI: 10.1371/journal.pone.0047981
Images are available to download from http://www.kew.org/press/images/index_kew.html. Please contact the RBG Kew press office for a username and password
Notes to Editors
Part of this study was funded by the Bentham-Moxon Trust (Royal Botanic Gardens, Kew). http://www.kew.org/about-kew/policies-information/bentham-moxon/grants/index.htm. Fieldwork in South Sudan was funded by the USAID JGMUST Project and World Coffee Research (WCR) http://worldcoffeeresearch.org/. Publication costs were supported by WCR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
More about coffee
Coffee is said to be the world's favourite beverage, with over 500 billion cups consumed each year. The crop is grown in tropical enviroments around the world, with some 70 countries producing coffee, from the Americas to Australasia and the Pacific. Coffee is the second-most traded commodity after oil, and the world's most important agricultural commodity. In 2009/10, when some 93.4 million (60 kg) bags were shipped, coffee accounted for exports worth an estimated US$ 15.4 billion. Coffee sector employment is estimated at about 26 million people in 52 (of the 70) producing countries. Coffee plays a crucial role in the economies of several tropical countries, accounting for a significant proportion of tax income and gross domestic product. [Trade figures from International Coffee Organization http://www.ico.org]. Arabica coffee and Robusta coffee (C. canephora) are the two main species used in the production of coffee, although the former is by far the most significant, providing approximately 70% of commercial production. Arabica is the main or sole component of high quality coffee, as used by all the well-known high street coffee chains.
Arabica coffee has a restricted natural range, being found only in the highlands of southern Ethiopia, a few locations in neighbouring South Sudan, and perhaps one locality in northern Kenya (Davis et al., 2006; and as an outcome of the present study). Wild Arabica is considered important for the medium to long-term sustainability of the Arabica coffee industry because the Arabicas used in the world's coffee plantations are from very limited genetic stock (Lashermes et al., 1996; Anthony et al. 2001; Labouisse et al., 2008) and are unlikely to have the flexibility required to cope with climate change and emerging threats (e.g. pests and disease). Genetic diversity from wild plants or natural populations is a vital source of genes for crop improvement. Useful traits, such as resistance to pests and diseases, drought tolerance, and improved food quality, can be transferred (e.g. via breeding programmes) from wild relatives to crop species. It has been estimated that the total genetic diversity contained within the world's coffee plantations is less than 5% of that occurring in the wild, and could be as low as less than 1%. The economic value of Arabica genetic resources contained in the highland forests of Ethiopia, in terms of use in breeding programmes for improved coffee cultivars, has an estimated value to the coffee industry of up to 1458 million US$ for a 30 year period (Hein & Gatzweiler, 2006).
The Royal Botanic Gardens, Kew and coffee research
Kew is a world leader on the study of wild coffee species, with staff members describing more than 30 of the 103 species now known to science, and 21 new species discovered in the last 10 years alone. In particular Kew is committed to providing information for the conservation of wild coffee genetic resources, including data from genetic studies and satellite imagery. Knowledge of wild crop relatives is essential for the long-term sustainability of agricultural commodities, such as coffee. More info here http://www.kew.org/plants-fungi/kew-stories/kew-research/coffee-family/
Species profile of Coffea arabica http://www.kew.org/plants-fungi/species-browser/Coffea-arabica.htm
The Royal Botanic Gardens, Kew is a world famous scientific organisation, internationally respected for its outstanding living collection of plants and world-class Herbarium as well as its scientific expertise in plant diversity, conservation and sustainable development in the UK and around the world. Kew Gardens is a major international visitor attraction. Its landscaped 132 hectares and RBG Kew's country estate, Wakehurst Place, attract nearly 2 million visitors every year. Kew was made a UNESCO World Heritage Site in July 2003 and celebrated its 250th anniversary in 2009. Wakehurst Place is home to Kew's Millennium Seed Bank, the largest wild plant seed bank in the world. RBG Kew and its partners have collected and conserved seed from 10 per cent of the world's wild flowering plant species (c.30, 000 species). The aim is to conserve 25 per cent by 2020, and its enormous potential for future conservation can only be fulfilled with the support of the public and other funders.
Kew receives funding from the UK Government through Defra for approximately half of its income and is also reliant on support from other sources. Without the voluntary monies raised through membership, donations and grants, Kew would have to significantly scale back activities at a time when, as environmental challenges become ever more acute, its resources and expertise are needed in the world more than ever. Kew needs to raise significant funds both in the UK and overseas.
Journal
PLoS ONE