The Impact of Climate Change on Indigenous Arabica Coffee (Coffea arabica ): Predicting Future Trends and Identifying Priorities Aaron P. Davis1*., Tadesse Woldemariam Gole2, Susana Baena1, Justin Moat1*. 1 The Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, United Kingdom, 2 Environment and Coffee Forest Forum, Addis Ababa, Ethiopia Abstract Precise modelling of the influence of climate change on Arabica coffee is limited; there are no data available for indigenous populations of this species. In this study we model the present and future predicted distribution of indigenous Arabica, and identify priorities in order to facilitate appropriate decision making for conservation, monitoring and future research. Using distribution data we perform bioclimatic modelling and examine future distribution with the HadCM3 climate model for three emission scenarios (A1B, A2A, B2A) over three time intervals (2020, 2050, 2080). The models show a profoundly negative influence on indigenous Arabica. In a locality analysis the most favourable outcome is a c. 65% reduction in the number of pre-existing bioclimatically suitable localities, and at worst an almost 100% reduction, by 2080. In an area analysis the most favourable outcome is a 38% reduction in suitable bioclimatic space, and the least favourable a c. 90% reduction, by 2080. Based on known occurrences and ecological tolerances of Arabica, bioclimatic unsuitability would place populations in peril, leading to severe stress and a high risk of extinction. This study establishes a fundamental baseline for assessing the consequences of climate change on wild populations of Arabica coffee. Specifically, it: (1) identifies and categorizes localities and areas that are predicted to be under threat from climate change now and in the short- to medium- term (2020–2050), representing assessment priorities for ex situ conservation; (2) identifies ‘core localities’ that could have the potential to withstand climate change until at least 2080, and therefore serve as long-term in situ storehouses for coffee genetic resources; (3) provides the location and characterization of target locations (populations) for on-the-ground monitoring of climate change influence. Arabica coffee is confimed as a climate sensitivite species, supporting data and inference that existing plantations will be neagtively impacted by climate change. Citation: Davis AP, Gole TW, Baena S, Moat J (2012) The Impact of Climate Change on Indigenous Arabica Coffee (Coffea arabica): Predicting Future Trends and Identifying Priorities. PLoS ONE 7(11): e47981. doi:10.1371/journal.pone.0047981 Editor: Brock Fenton, University of Western Ontario, Canada Received May 18, 2012; Accepted September 19, 2012; Published November 7, 2012 Copyright: 2012 Davis et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: 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 World Coffee Research (WCR). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: a.davis@kew.org (APD); j.moat@kew.org (JM) . These authors contributed equally to this work. Introduction Coffee (Coffea L.) is the world’s favourite beverage and the second-most traded commodity after oil. In 2009/10 coffee accounted for exports worth an estimated US$ 15.4 billion, when some 93.4 million bags were shipped, with total coffee sector employment estimated at about 26 million people in 52 producing countries [1]. Arabica coffee (Coffea arabica L.) and robusta coffee (C. canephora Pierre ex A.Froehner) 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 produc- tion [1]. The productivity (green bean yield) of Arabica is tightly linked to climatic variability, and is thus strongly influenced by natural climatic oscillations [2]. The stated optimum mean annual temperature range for Arabica is 18–21uC [3], or up to 24uC [4]. At temperatures above 23uC, development and ripening of fruits are accelerated, often leading to the loss of beverage quality [5], although in some locations higher temperatures (24–25uC) can still produce satisfactory yields of beans, such as in northeast Brazil [6]. Continuous exposure to temperatures as high as 30uC leads to stress, which is manifest as depressed growth and abnormalities, such as the yellowing of leaves and growth of tumours on the stem [7]. In regions with a mean annual temperature below 17–18uC growth is also depressed [8]. Occurrence of frosts, even if sporadic, may strongly limit the economic success of the crop [5]. The relationships between climatic parameters and agricultural pro- duction is further complicated because these environmental factors influence the growth and the development of the plants in different ways during the various growth stages of the coffee crop [2]. The Intergovernmental Panel on Climate Change [9] predicts that best estimates for average global temperatures, across all scenarios, will be between 1.8uC to 4uC by the end of the twenty- first century. Global temperatures have increased by an average of 0.74uC (+0.56uC to 0.92uC) in the last 100 years (1906–2005), and this increase appears to have accelerated since the 1970s [9]. On this basis it has been forecast that the sustainability of the coffee industry faces serious challenges in the coming decades [2,10–14]. The evidence from coffee farmers, from numerous coffee growing PLOS ONE | www.plosone.org 1 November 2012 | Volume 7 | Issue 11 | e47981