Coffee and Global Warming - the risk is out there

While most of the effects of global warming and climate change focus on rising seas, higher temperatures, ocean salinity, super storms and so on, a number of other impacts which will affect human population are often overlooked or sparsely presented. One aspect of climate change which will cause concern is the world-wide reduction of coffee supplies. Coffee is grown in over 70 countries around the world, supports over 26 million farmers and generates exports of over $15 billion a year mainly for developing countries. The coffee industry is reliant for two thirds of its production from just one species, Coffea arabica, which originated from Ethiopia over four centuries ago. C. arabica requires temperatures between 180C and 210C with a reasonable mix of dry weather (for buds to grow) and wet weather (for flowering). From 230C upwards the plant exhibits stress and produces poorer quality beans and above 300C the plant develops tumours and loses its leaves.

Between 2009 and 2012 coffee yields fell to a 35 year low due to extraordinary rains and then unseasonable dryness - a portent of events to come. According to the IPCC's most optimistic projections, by 2080 around 65% of current geographic locations for wild coffee will be unsuitable and this rises up to 99.7% at the worst case scenario. Coffee production will fall well before 2080 however and within the next twenty years. Matched with the changing temperature is the expanded proliferation of the coffee weevil,  Hypothenemus hampei which has spread to every coffee-producing country with the exceptions of Nepal and China. This small borer attackes the coffee beans and requires only a small temperature rise to increase the number of generations born in any cycle. On current trends and with estimates of warming up to 4 degrees Celsius higher, up to ten generations of borer could occur each year.

The only option is to find a substitute for C arabica form the 125 other species of coffee which might tolerate global warming and be drinkable. As yet, none have been positively proven although coffea canephora (also known as Robusta) shows promise.