Research press release


Nature Plants

Climate change brews trouble for Ethiopian coffee


世界のコーヒー豆収穫量の過半を占めるアラビカ種(Coffea arabica)はエチオピア原産で、同国の輸出額の4分の1を稼ぎ出している。そのため、気候変動がコーヒー生産に与える影響を理解しなければならないわけであるが、気候変動の影響を地域レベルで予測することは困難である。

Justin Moatたちは、異なる移動シナリオを展開し、世界気候研究計画(WCRP)が開発した高分解能の気候データおよび最新の衛星画像を利用して、1960年代から21世紀中までの4期間に関してコーヒー適性の予測を得た。これによってエチオピアは、1 km2ごとに、コーヒー栽培に不適、最低限、普通、良好、最高のいずれかに色分けされた。続いて研究チームは、2013~2016年の間に、約3万kmを車と徒歩で踏破して1800カ所以上を視察することにより、そのモデリングの正確度を検証した。


Climate change could make approximately half of Ethiopia’s coffee production area unsuitable for coffee agriculture by the end of this century, according to a paper published online this week in Nature Plants. It is not all bad news, however, as the study also suggests that relocation of coffee areas, along with forestation and forest conservation, could see the total size of the coffee farming area increase fourfold.

Arabica coffee (Coffea arabica), which provides the majority of the global coffee bean harvest, originated in Ethiopia and makes up a quarter of the country’s export earnings. As such, there is a need to understand the influence of climate change on coffee production, but predicting the effects of climate change at a local level is difficult.

Justin Moat and colleagues developed different migration scenarios, used high resolution climate data developed by the World Climate Research Programme (WCRP) and the latest satellite imagery, to produce coffee suitability projections across four time periods, starting in the 1960s and continuing through the twenty-first century. This allowed them to classify each square kilometre of Ethiopia as unsuitable, marginal, fair, good or excellent for coffee growing. The researchers then tested the accuracy of the modelling by visiting over 1,800 sites between 2013 and 2016, covering some 30,000 km by road and on foot.

They find that 39-59% of current coffee production areas could be unsuitable for coffee agriculture by the end of this century, clearly showing the scale of the threat posed by climate change. However, the authors also suggest that rising temperatures associated with climate change could bring additional regions of the country into coffee agriculture over the next 20 years. Finally, they identify those regions of forest that will be best able to act as refuges for preserving the genetic diversity of wild Arabica coffee.

doi: 10.1038/nplants.2017.81


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