Coffee Plants Don’t Like It Hot
Guest blogger Atreyee Bhattacharya is a science correspondent and climate scientist, currently a research affiliate at the Department of Earth and Planetary Sciences, Harvard University.
Like most, I like my coffee black and piping hot. Coffee plants, however, may not be as fond of the heat.
When thinking about the impact of changing climate (increased droughts, wilder fluctuations in seasons) and increasing pest activity on food production—my thoughts tend toward crops such as rice, wheat, and corn. Not so much wine, chocolate, or coffee, though I probably consume more coffee throughout the day than I do these other staples.
However, two recent papers published in PLOS ONE deliver a double whammy to coffee, or more particularly the Coffea arabica plant, a species that today accounts for more than 70 percent of the world’s coffee. (Another, less common, variety is C. robusta, which has twice the caffeine content.)
In a 2011 study, Juiliana Jaramilo from the University of Hannover and her coauthors, showed that warming air and land temperatures can change the distribution of the coffee berry borer Hypothenemus hampei in East African C. arabica producing regions.
The borer, a pest that attacks coffee beans, “causes losses exceeding US $500 million annually, and worldwide affects many of the more than 25 million rural households involved in coffee production” the study reports. A serious infestation can lower coffee production by more than three times!
Until about ten years ago, reports of H. hampei attacks on coffee plants growing above 1500 m (the preferred altitude of cultivated and naturally occurring C. arabica) were few and far between. But thanks to the 0.2-0.5 degrees Celsius temperature increase in coffee growing regions of East Africa, the pests are now found at higher altitude plantations as well.
As temperatures continue to rise as per projections from the Intergovernmental Panel on Climate Change (IPCC), coffee borer infestations in this region are likely to spread farther. Increasing temperatures will increase the number of H.hampei generations each year from 1-4.5 to 5-10 or more.
“These outcomes will have serious implications for C. arabica production and livelihoods in East Africa,” caution the authors, adding, “We suggest that the best way to adapt to a rise of temperatures in coffee plantations could be via the introduction of shade trees in sun grown plantations.”
Though C. arabica plants do like to grow in the shade; another study indicates that this protection may still not be enough to combat the threat of warming temperatures. According to this research by Aaron Davis from the Royal Botanic Gardens in the United Kingdom, warming temperatures may make several localities within southwest Ethiopia and neighboring regions climatologically ill-suited to growing C. arabica.
“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,” write the researchers.
According to their estimates, the most favorable outcome of warming is a 65% decrease in areas with climate suitable for coffee plantations, and at worst, an almost 100% loss of these regions by 2080. In terms of available area for growing coffee, the most favorable outcome is a 38% reduction in suitable space, and at worst a 90% reduction. Neighboring areas could fare even worse by as early as 2020.
Coffee is a 90-billion-dollar industry , but it is an industry that depends on long-term planning. The beans that we grind every morning today were planted about 7-10 years ago, and our morning brew a decade hence depends on today’s plantations.
Demand for coffee continues to rise in our ‘coffee culture’, and C. arabica still constitutes about 75-80% of the world’s coffee production. C. arabica is believed to be the first species of coffee to be cultivated, well over a thousand years ago. It epitomizes an incredible journey, and is one beverage that is certainly worth a second thought as rising temperatures threaten its existence.
Read these studies and more on the ecological impacts of climate change in the new PLOS Collection: http://www.ploscollections.org/ecoclimatechange
Citations:Jaramillo J, Muchugu E, Vega FE, Davis A, Borgemeister C, et al. (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(9): e24528. doi:10.1371/journal.pone.0024528
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
Espresso by Richard Masoner on Flickr
Distribution of the coffee berry borer (Hypothenemus hampei) in Eastern Africa under current climate. The EI values (0–100), indicates unsuitability of the location’s climate (0), and a ‘perfect’ climate for the given species (100). doi:10.1371/journal.pone.0024528.g001
Predicted and actual distribution of indigenous Arabica. Green dots show recorded data-points. Colored areas (yellow to red) show predicted distribution based on modeling. A context map is given in the top left hand corner. doi:10.1371/journal.pone.0047981.g001