Nanogirl Michelle Dickinson: World's coffee species at risk of exinction

Poor coffee farmers in African countries are being forced to switch the use of their land to more resilient products such as livestock. Photo / Getty Images

With a recent study showing that 60 per cent of all coffee species are under threat of extinction, waking up to a cup of coffee in the morning may soon become a more expensive and less tasty affair.

One of the world's most widely consumed beverages, coffee supports a multibillion-dollar global industry – from small local farmers in developing countries to large international food and beverage chains.

A study, published in the journal Science Advances, has provided the most comprehensive map of location and health of coffee species worldwide, and the results are alarming.

Most of the coffee that we drink comes from two species of coffee plant: Coffea arabica produces arabica coffee, and Coffea canephora produces robusta coffee. The coffee group of plants is far more diverse than these two well-known species – there are 124 known species of coffee. Many of these are wild varieties found in tropical Africa, some islands in the Indian Ocean, and in regions through Asia and Oceania.

Diversity within crops – having a wider variety of species available than the two primary commercial products – is important as it helps farmers to cross-breed plants. That means farmers can develop and grow coffee that is resistant to changing climates and various pests. As a result, with more of these wild coffee varieties being wiped out, the future security of the commercial coffee bean is potentially at risk.

The study started with more than 5000 records of wild coffee species from previous research. The researchers then travelled on several expeditions through key coffee growing areas in Africa, including Madagascar, and some other islands in the Indian Ocean. They were able to determine which of the habitats were at risk due to climate and deforestation changes. Staggeringly, they found that 60 per cent of coffee species at risk of extinction.

To put that number in perspective, the global figure for the number of plant species overall that are threatened with extinction is 22 per cent. At 60 per cent, coffee plants are at one of the highest levels of risk recorded for any plant group in the world.

One of the main threats lies in climate change. Coffee plants have very specific requirements in terms of what they need to survive. They need to be at altitude in a cool, shade-filled, forested area that has both a wet and a dry season. Increasing levels of deforestation for housing and palm oil, coupled with rising temperatures and increased rainfall associated with climate change are making it impossible for coffee to grow in places that it once thrived.

In addition to habitat loss due to climatic change, the coffee plant is at further risk from economic pressures facing the growers, causing them to consider changing land use and so further restricting the available habitat.

More than 80 per cent of coffee growers are poor farmers in less developed countries. Increasing global temperatures and increased droughts are forcing many of these farmers to switch the use of their land away from coffee growing to more predictable and resilient products – livestock in particular.

It doesn't end there. The coffee plant produces a beautiful timber that is usually straight, hard and resistant to termite infestation – as a result, it is understandably tempting for growers to harvest the timber for small, local construction projects.

These factors combined represent a real risk to the future of many species of coffee, and the knock-on effects of decreasing diversity. Although the varieties of coffee we drink are not in immediate danger of extinction, they too are not immune to these risks. A change of even a couple of degrees in growing temperature can severely reduce the quality and taste of the commercial coffee beans that we know and love.

Dr Michelle Dickinson, creator of Nanogirl, is a nanotechnologist who is passionate about getting Kiwis hooked on science and engineering. Tweet her your science questions @medickinson