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Imagine a world without coffee. No heart starter in the morning. No coffees to fuel bad days at work or all-nighters to meet impossible deadlines. No barista-poured fancy patterns on your cappuccino, no short blacks to fortify driving home in traffic or strap-hanging for an hour. Doesn't sound like a world you want to inhabit? You may have no choice if we continue to use resources like there is no tomorrow.

Where does coffee come from?

coffee beans on coffee plant

coffee beans on coffee plant

Coffee is derived from the seeds of certain species of the Coffea shrub. The Coffea genus contains over 120 species.

The two most common species cultivated are

  • Coffea arabica (Arabica) which accounts for 60 - 80 % of the global coffee production. Optimal temperature range 15 to 24ºC. Ideally, 1500-2500 mm of rain will fall over a nine month period with a three month dry season coinciding with the harvest. Arabica does best at higher altitudes and is often grown on hillsides.
  • Coffea canephora (Robusta) which accounts for 20 - 40 % of the global coffee production. Optimal temperature range 24 to 30ºC averages, with annual rainfall in the 1500 to 3000 mm range. Robusta does best at lower elevations -sea level to 800m.1

Coffea plants start bearing at about 5 years and they have a life span of 30-50 years.

A mature bush yields 1.5–4.0 kilograms of ripe fruit each year, which, when processed and dried, results in about 250–600 grams of dry green beans.

Arabica is regarded as the plant which produces coffee with the best taste. Robusta is generally used to produce instant coffee and other lower quality products.

Global coffee supply

Map of Coffee Growing Countries

Coffee Growing Countries

Coffee is regarded as one of the most valuable food commodities in the world and 11 million ha worldwide are used to grow coffee. Coffee growing regions are found between the Tropic of Cancer and the Tropic of Capricorn.

Coffee production for 2020 from Feb 2021 to Jan 2022 about 128,981,958 standard bags. A standard bag weighs 60kg. Coffee consumption has quadrupled over the last  4 decades.

Biggest producers

  1. Brazil
  2. Vietnam
  3. Colombia

Current and historical data at , the International Coffee Organization.

Factors which threaten the production of coffee

Physical features

Climate change will reduce the global area suitable for coffee by about 50 % across emission scenarios. Impacts are highest at low latitudes and low altitudes.2  In this somewhat technical paper, the authors outline the fortunes of various areas for coffee production in terms of climate factors.

C. arabica has been said to be genetically predisposed to extinction in the face of change. Cultivated C. arabica plants have a very low genetic diversity index (often quoted as just 1.2%, compared with more than 20% for other crops.) 3 This lack of diversity makes it less able to adapt to changing conditions.

Wild Coffea spp. are also threatened 4, 5 and this is significant in terms of exploring currently underutilised potential crop plants as well as maintaining a diverse source of Coffea spp. genes.


bee pollinating coffee flower

bee pollinating coffee flower

C. robusta requires cross-pollination by insects.
C. arabica is self-fertile i.e. the pollen passes from the anther to the stigma inside the same flower. However, bee pollination is known to enhance quantity and quality of yield.

The main pollinators of coffee flowers are different kinds of bees. Other pollinators of coffee include many different kinds of wasps, large flies, butterflies and moths.

Climate change is interfering with pollination by disrupting the synchronized timing of flower blooming and the timed appearance bees pollinators. Bees are also at risk due to use of pesticides.

Pests and diseases

Coffee leaf rust disease

Coffee leaf rust disease

Coffea plants are attacked by

  • Coffee leaf rust (fungal) Image shows leaves infested with this fungus.
  • Coffee borer beetle
  • Bacterial blight (bacteria)
  • Coffee berry disease (fungal)
  • Twig borer beetle
  • Nematodes

Arabica is particularly susceptible to coffee leaf rust fungus.

Example of the scope of pest attacks

In the 2012-2013 season, under conditions of unusually high temperatures and high-altitude rains, Coffee leaf rust (Hemileia vastatrix) caused a dramatic outbreak of the disease over much of Latin America, from Peru, Central America and Mexico to the Dominican Republic. Incidence levels reached 80% in some growing regions with yield reductions of 17% across Central America compared to the previous year.6
The coffee berry borer (Hypothenemus hampei) – The coffee berry borer (Hypothenemus hampei), one of the most important pests of coffee worldwide, has already benefited from the temperature rise in East Africa: increased damage to coffee crops and expansion in its distribution range have been reported.7

What can we do about it?

Solutions involve scientific, technical, social, legal and economic factors to varying degrees.

Climate change, as a result of global warming, is expected to result in actual shifts on where and how coffee may be produced in future. Several adaptation and mitigation strategies for coffee producers have been put forward in response to the challenges facing the sector. One approach that is being pursued vigorously is engineering of the Arabica genotype. While faster than conventional crossbreeding programs, this could result in patents being registered on new genotypes generated in labs with all the issues associated with ownership, costs and management. See 8, 9

Short-term adaptation strategies include improved farming practices and better post-harvest processing.

Longer-term strategies include capacity-building, improved monitoring of climate data, enhancing soil fertility, introducing or preserving different production models, and developing drought and disease-resistant varieties. For example, research has been carried out into growing Coffea stenophylla on a commercial basis. It has been used before but had fallen out of fashion.10   Although it does not bear as heavily as Arabica, it is a more resilient plant, and is reported to have a similar taste.

Mitigation strategies include calculating and reducing greenhouse gas emissions on the farm, and facilitating the creation of carbon sinks. However, the coffee industry is not a major CO2 polluter, so its ability to influence overall emissions is quite limited.

And there are those who see global climate warming as requiring high level government environment intervention to rescue the whole earth.

  • Consider who you vote into power in your country
  • Consider your own consumption patterns and who you buy from
  • Consider the future and what you want it to look like

Acknowledgement of issues not covered on this page

The social effects of change for small farm-holders, the politics of the producer countries, the use of child slaves for labour

Information starting points for more information about societal aspects of coffee.

How the raw product is turned into the commodity.




When the coffee plant fruit (cherry) is ripe, the cherries are picked either by hand (on slopes) or by machine on flatter terrain.

Hand picking can be selective - only the ripe cherries are picked and multiple passess are are made so that each cherry is picked at maximum ripeness. If this is too expensive for a farmer, strip picking i.e. picking all berries in bunch at one time is quicker and cheaper.

Mechanical picking may accomplished by individuals picking using mechanised hands.

According to Julio Guevara

The second option is to use stripping machines. These are much bigger, and are often driven around the farm. This means they can harvest much more coffee in the same time. They have rotating and vibrating rods that knock the cherries loose. A system of plates and pipes then catches them and transfers them to a holding bin.

He then goes on to explain the pros and cons of different methods.

Milling and bagging



Once the cherries are picked, they are immediately processed by either the Wet Method or the Dry Method. The Dry Method involves spreading the cherries out on sheets and leaving them to dry in the sun. They need frequent turning and protection from rain. This continues until the moisture content reaches an appropriate level.

The Wet Method as the name suggests uses water (in substantial amounts to soak the cherries and remove the ovary wall of the fruit. This method relies on fermenting the bean water mixture and must be very closely monitored to ensure fermentation does not introduce any undesirable flavours. Other hybrid methods have evolved depending on local resources and climate variations.

Once the beans have reached the required level of drying, they are hulled to remove whatever external covering remains. At this stage,  any defective beans are removed, and beans are sorted on the basis of size and colour.

The coffee beans are known as green coffee and are bagged for export or bulk loaded for export.


commercial roasting factory

commercial roasting factory

Roasting transforms green coffee into the aromatic brown beans that we think of as coffee beans.

As the beans are subjected to the high temperatures in the roasting chamber, they begin to turn brown and a fragrant oil  called caffeol emerges. This process is called pyrolysis. The beans can be roasted for variable amounts of time to achieve the desired shade of brown. Roasting is usually done in the import country as roasted coffee does not store well compared to green coffee.


Coffee can be purchased as beans or pre-ground. The granularity of the grind can be matched to the method of brewing the coffee in order to get the maximum flavour. If the beans are to be used for instant coffee instead of for brewing, they are processed by freeze drying or spray drying.



Think long term!

Notes on images this site

Many of the images on this site can be enlarged by clicking on them

  1. Climate and Pest-Driven Geographic Shifts in Global Coffee Production: Implications for Forest Cover, Biodiversity and Carbon Storage[]
  4. Coffee in trouble: 60% of wild coffee species threatened with extinction[]
  5. World's coffee under threat, say experts[]
  6. FAO collaborates in fight against coffee rust disease in Central America[]
  7. Some Like It Hot: The Influence and Implications of Climate Change on Coffee Berry Borer (Hypothenemus hampei) and Coffee Production in East Africa[]
  8. Climate-Ready Crops: The Pros and Cons []
  9. Vandana Shiva, Stolen Harvest: The Hijacking of the Global Food Supply"[]
  10. Future-Proofing Coffee With the Long-Lost Coffea stenophylla[]