Buzzkill: Arabica coffee plantations under increasing threat from the effects of climate change

Note that this content is from an article I wrote as part of my BSc degree in 2014. The latest reports indicate that coffee production and consumption have both increased since the slump of 2013 – 2016, while prices have shown a downward trend. Despite this, I think that the article remains relevant especially concerning coffee production and means of mitigating the inevitable effects of climate change.

Originating in the horn of Africa with cultivation possibly starting in Yemen around six
centuries ago, coffee is now one of the most popular hot drinks worldwide1. After oil, coffee is the world’s second-most traded commodity with 93.4 million bags, worth a staggering US $15.4 billion (£9.27 billion) exported from coffee-growing countries in 2009/2010. Now it seems that the world’s coffee-producing regions may be under threat from the effects of climate change, according to Aaron Davis and Justin Moat from Kew.

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By all accounts, we love our coffee, with nearly a third of the world’s population drinking it. The USA imported almost 27 million bags between November 2012 and October 2013 while the UK imported around 4 million bags over the same period, according to the International Coffee Organization (ICO). In total, worldwide imports for the 2012/2013 coffee season were an astonishing 133.9 million bags.

Reduction in productivity, increased and intensified management, and crop failure.

Of the 125 species of coffee plants found naturally, the two main types used in the production of coffee are arabica and robusta. Originally from the high-altitude, humid evergreen forests of Ethiopia and South Sudan, arabica is known to be climate sensitive with an ideal average temperature of between 18°C and 23°C and well-defined rainy and dry seasons. Arabica coffee is now grown in 52 countries worldwide. Robusta, as its name implies, is more comfortable with higher temperatures and produces a greater crop yield than arabica. With its higher caffeine content and more bitter flavour, robusta tends to be used in instant coffees while arabica is considered superior in quality and taste making up 70% of all commercially produced coffee. There are now thought to be around 26 million people working in the coffee sector worldwide. Our demand for coffee has never been greater and yet a series of climate-linked and interrelated problems such as increased temperature, unpredictable rainfall, the spread of insect pests and diseases, intensive farming, and urbanization could spell the end of coffee as we know it.

It’s getting hotter

Ethiopia (the fifth largest global exporter of coffee and Africa’s main coffee-producing nation) was used as an example by Davis and Moat when they looked at the possible future distribution of arabica coffee. They based their findings on the Intergovernmental Panel on Climate Change’s (IPCC’s) best estimates of anticipated temperature rises of 1.8°C to 4°C in global temperatures by the end of the twenty-first century and found that coffee production was likely to decrease significantly. Worryingly, they also found that there would be less land that is suitable for growing coffee, saying that it would lead “…to a reduction in productivity, increased and intensified management…and crop failure.”

Countries whose economies depend heavily on agriculture for their development may be hardest hit by a change in climate.

Responding to warming temperatures, some farmers are starting to grow their crops further up hillsides and mountain slopes. At higher elevations, where the temperature is slightly cooler, the arabica plants thrive once again. It is, however, harder to farm at higher altitudes and we cannot keep going up the mountains, we’ll simply run out of farmable land. There is also expected to be a climatic shift in latitudes so that the tropics and subtropics effectively move away from the equator, but this is incredibly difficult to predict because of air currents, ocean currents and local geography all affect this and act on one another. In a report by the International Trade Centre (ITC) entitled ‘Climate Change and the Coffee Industry’ the authors note that any shift in altitude or latitude may adversely affect the quality of the coffee and fewer parts of the world may end up being able to support arabica coffee production.

Unpredictable rainfall

As air and ocean temperatures rise, it is likely that wet areas will get wetter and dry areas will get drier according to both the ITC and IPCC. This is the rule-of-thumb measure for regions, but there is also expected to be far more variability; that is, more extreme droughts and more heavy rainfall. The increased warming will mean that for every 1°C increase in temperature the plants and animals that live in a certain area because the climate conditions are perfect for them there will have to shift by 160 km (about the distance between Birmingham and London as the crow flies) north or south, following those perfect conditions. In the case of some island nations a 160 km shift could be catastrophic. We should expect more humidity and higher rainfall to accompany the hotter tem- peratures. The seasonal and geographical rainfall and temperature patterns that we have all grown used to will change because of these shifts. This is of course incredibly bad news for arabica which needs quite particular weather conditions.

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Intensive farming methods

The way in which the coffee is grown can also contribute to some difficulties. Traditionally, coffee was grown under taller trees and shrubs of different heights with a large mix of plant species. This meant that the coffee plants grew in shade and that the soil was rich with the nutrients of all of the accumulated dead plant matter. On a number of farms this method of growing has been abandoned in favour of plantation-style planting which means that the farmer can squeeze more plants into an area and improve the size of the yield. This involves clearing the land by chopping down the trees, sometimes burning, and planting sun-resistant varieties of coffee that have been bred to tolerate growing in direct sunshine. This intense planting regime also requires the addition of many tonnes of expensive man-made fertilizers and chemical controls such as fungicides and pesticides every year. These changes in production practices have been found to exacerbate the problems associated with coffee-growing according to Juliana Jaramillo, from the Institute of Plant Diseases and Plant Protection, at the University of Hannover in Germany. Studying a coffee-producing area near Nairobi in Kenya, Jaramillo and her colleagues found that open plantations were 2°C higher than shaded ones. Obviously, the associated warmer temperatures are a problem for arabica growing, but it can also present coffee-growers with a whole new set of problems. The increased exposure to heavy rain can lead to nutrients being leached out of the soil, soil conditions quickly deteriorate leading to soil erosion, and in the worst cases, water run-off that turns into floods and landslides. This becomes a cyclical problem, as crops fail or yields decrease, more intensification occurs to make up the shortfall and worsens the conditions.

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The spread of insect pests & diseases

As with any crop plant, coffee can suffer from attacks by insect pests and diseases. With even small temperature rises and changes in rainfall patterns, these pests and diseases become more common and more difficult to control. The coffee berry borer beetle is the most destructive pest of commercially grown coffee, causing crop losses of more than US $500 million (£300 million) per year. These beetles actually benefit from increases in temperature. Based on a 1°C temperature rise over the next 50 years, Jaramillo expects to find the beetles reproducing faster and spreading further. Even now the insects are being found 300 metres higher up the slopes of Mt. Kilimanjaro in Tanzania than where they used to be ten years ago.

A devastating outbreak of coffee leaf rust in Central America was reported by Reuters News Agency in July 2013. The rust is very damaging to crop yields and was responsible for a 15% drop in production from the region last season with even worse effects expected for 2013/2014. Warm temperatures and high humidity are ideal conditions for the rust to spread, but it also needs the leaf that it is colonising to be wet to be able to first become established. Increased warming and heavier than usual rainfall in the region has created the perfect incubator for the rust. Ironically, another fungus, the white halo fungus, which attacks and partially controls the spread of the rust
has been wiped out by the systematic spraying of chemicals. “What we feel has been happening is that gradually the integrity of this once-complicated ecosystem has been slowly breaking down, which is what happens when you try to grow coffee like corn,” said US ecologist John Vandermeer.

The integrity of this once- complicated ecosystem has been slowly breaking down.

Rather than responding to temperature rises, the coffee white stem borer beetle, a major coffee pest in Zimbabwe, is becoming more common because of changes in rainfall. Adult beetles emerge from the infested coffee plants in the rainy season and with increased periods of rainfall up to 200% more beetles are expected there by the year 2080 says Dumisani Kutywayo and colleagues from the Coffee Research Institute (CRI). A quarter of Zimbabwe’s yield losses are due to infestation by coffee white stem borer and as rainfall patterns become more unpredictable and seasonality shifts, coffee farmers’ outlook can only be described as gloomy.

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What is to be done?

In the face of catastrophe, all is not lost. The planting of coffee plants under a mixed canopy of plants has shown time and again to be a very effective model for controlling temperature. This form of planting is known as agroforestry and apart from creating more favourable conditions for coffee growing also allows the farmer to grow an additional crop such as bananas. This model is already in use across the coffee-growing world and as Helton Nonato de Souza from the Department of Soil Quality, Wagenin- gen University in The Netherlands explains: agroforestry creates shade, maintains a cooler air temperature, improves the condition of the soil, retains soil moisture, and limits damage from high rainfall. In their study area in the Brazilian Atlantic Rainforest, de Souza and his team also identified not only a vast array of tree species average of 60% greater biodiversity than the surrounding forests.

This species richness is an invaluable part of a healthy ecosystem and contributes to the well being of the coffee plants through biological controls. Pests and diseases can be controlled by their natural predators instead of chemicals as long as we provide a space for them to live according to the US ecologist, Daniel Karp.

There is also ongoing research into developing new breeds of arabicas that are less heat-sensitive or show more resistance to pathogens and diseases. Returning to the birthplace of coffee; some coffee plants with resistance to extremes in temperature have recently been found in the Ethio- pian Great Rift Valley.

90% of all coffee production is located in the developing world.

Screenshot 2018-09-29 at 11.47.33.pngAll the signs regarding arabica coffee growing in an age of global climate change are troubling. We must expect that production will probably decrease, that quality may be affected, prices will rise, and that the livelihoods of millions of people are at risk. With many farmers finding conditions more difficult with less income, there is the real risk that intense production of higher-income cane sugar, palm oil, cocoa leaf or khat replace coffee. What is needed is a reevaluation of the pricing structure of coffee linked to new patterns of behaviour that value the wider natural system within which it is grown. With the fair financial support of consumers, coffee farmers will be able to take steps to protect their livelihoods from the devastations of unpredictable rainfall, increasing temperatures and the growing abundance of pests and diseases. There is now an opportunity for more farmers to embrace small-scale, shade-grown coffees that will benefit the wider environment, keep their businesses sustainable and keep producing good quality coffees.

As a Roaster from a coffee company in London said in an interview for this article: “The consumers have the knowledge, the power and the resources to do something proactive. If the consumer is willing to pay more from an ethical company … then the farmers have the resource to invest in strategies that will help to mitigate the issue [of climate change].


Kew Royal Botanical Gardens Last accessed 04/03/142

International Coffee Organization Last accessed 01/03/14

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

US Department of Agriculture (2013) “Coffee: World Markets and Trade” Last accessed 22/02/14

Kasterina A, Scholer M, and van Hilten HJ. (2010) “Climate Change and the Coffee Industry.” International Trade Centre ucts/Climate-Coffee-Ch-13-MS-ID-3-2-2010ff_1.pdf

Wexler A. “Arabica-Coffee Prices Climb to 16-Month Highs.” Wall Street Journal 19/02/2014 Last accessed 26/02/14

Jaramillo J, Setamou M, Muchugu E, Chabi-Olaye A, Jaramillo A, et al. (2013) “Climate Change or Urbanization? Impacts on a Traditional Coffee Production System in East Africa over the Last 80 Years.” PLoS ONE 8(1): e51815. doi:10.1371/journal.pone.0051815

Kutywayo D, Chemura A, Kusena W, Chidoko P, and Mahoya C. (2013) “The Impact of Climate Change on the Potential Distribution of Agricultural Pests: The Case of the Coffee White Stem Borer (Monochamus leuconotus P.) in Zimbabwe.” PLoS ONE 8(8): e73432. doi:10.1371/journal.pone.0073432

de Souza HN, de Goede RGM, Brussaard L, Cardoso IM, Duarte EMG, Fernandes RBA, Gomes LC, and Pulleman MM. (2012) “Protective shade, tree diversity and soil properties in coffee agroforestry systems in the Atlantic Rainforest biome.” Agriculture, Ecosystems and Environment. 146, 179-196

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

Nicholson M. “Central American coffee leaf rust sends roasters to new markets for beans.” Reuters News Agency 10/07/2013 Last accessed 01/03/14

Jackson D, Skillman J, and Vandermeer J. (2012) “Indirect biological control of the coffee leaf rust, Hemileia vastatrix, by the entomogenous fungus Lecanicillium lecanii in a complex coffee agroecosystem.” Biological Control. 61:1, 89-97

Erickson J. “Modern growing methods may be culprit of ‘coffee rust’ fungal outbreak.” Michigan News: University of Michigan. 12/02/2013

Karp DS, Mendenhall CD, Sandi RF, Chaumont N, Ehrlich PR, Hadly EA, Daily GC. (2013) “Forest bolsters bird abundance, pest control and coffee yield.” Ecology Letters. 16:11, 1339-1347

Gonthier DJ, Ennis KK, Philpott SM, Vandermeer J, and Perfecto, I. (2013) “Ants defend coffee from berry borer colonization.” BioControl: Journal of the International Organization for Biological Control. 58:6, 815-820

Author: Gino Brignoli

Currently employed as FSC BioLinks Project Officer for London, I am coordinating invertebrate-focused place-based volunteer training and delivering a range of recording project activities across London. I am also developing and delivering online training courses and content focusing on invertebrate taxonomy, field ID and ecology through a virtual learning platform. You can find out more about the project here. Previously ant genomics and evolution Research Assistant at Queen Mary University of London. With a keen interest in ecology and entomology, I have volunteered with the Lepidoptera department and Soil Biodiversity Group at the Natural History Museum, and on the Thorn to Orchid and Water for Wildlife projects with London Wildlife Trust.

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