Rising temperatures are a major reason for the Earth's sixth mass extinction, spreading of diseases, and are set to drive millions from their homes. However, maybe the thing that will finally drive serious action is the threat of boring coffee.
All plants have a range of temperatures in which they thrive. Global heating threatens those where this range is narrow. Moving to new locations is practical for short-lived plants, but less of a viable strategy for those that take years to fruit.
This may worry those who depend on coffee for their livelihoods – or just to wake up. Two studies released in the last week have investigated the likely consequences of a hotter world for major coffee producers Columbia and Ethiopia. Although neither predicts the plunge in production caffeine addicts worldwide fear, both have more subtle concerns to raise.
Ethiopia will probably experience an increase in the quantity of coffee it produces over the course of this century, Dr Abel Chemura of the Potsdam Institute for Climate Impact Research reveals in Scientific Reports. Unfortunately, the same cannot be said for quality.
“The area that is suitable for average quality coffee might actually increase gradually until the 2090s, according to our computer simulations," Chemura said in a statement. "Yet more is not necessarily better. Because on the flipside, the suitable area for high quality specialty coffee types which are valued for their floral, fruity and spicy notes, will likely shrink if climate change continues unchecked.”
As the original home of coffee, Ethiopia maintains varieties unknown elsewhere, such as Yirgacheffe – which could lose 40 percent of its growing range if temperatures stay on their current trajectory. Besides negative effects on small regions known for their distinctive varieties, higher temperatures accelerate the maturation of the coffee cherry faster than the bean, resulting in coffee of a lower quality.
As Chemura noted, this isn't just a problem for those who value coffer for its fine flavors rather than the accompanying caffeine rush. It's also a problem for growers reliant on premium prices to make up for small yields.
In Columbia, the news is better for consumers, but just as bad for some farmers. “Low-altitude municipalities will be negatively affected by climate change, and thousands of growers and their families in these areas will see their livelihood jeopardized because productivity is likely to fall below their breakeven point by mid-century," said University of Illinois PhD graduate Federico Ceballos-Sierra, who published an assessment in Agricultural Systems.
Ceballos-Sierra had direct experience, adding; "My family's farm is about 1,900 meters above sea level. Twenty years ago, people would consider that an upper marginal coffee growing area. But now we're getting significant improvements in yield,"
Policy-makers however, might be concerned about the consequence of plunging large numbers of low-altitude farmers into poverty in a country struggling to emerge from decades of civil war.
Climate affects coffee production in many ways. Chemura included 19 different climatic factors in his analysis – including temperature, rainfall, and humidity. Collectively, these indicated five of the six modeled specialist coffee growing areas in Ethiopia will suffer reduced yields or be forced to switch to cheaper but more robust varieties.