You've probably heard of coffee rust. No, not the accusatory ring that gets left on your mum's palewood table when you forget to use a coaster, coffee leaf rust (CLR) is a fungus that causes leaves to fall off coffee bushes, reducing the quality of the beans and increasing the plant's vulnerability to other diseases.
CLR wiped out about half of Central America's coffee crop in 2012, as well as many plantations in El Salvador, Guatemala, and Nicaragua. It's deemed such a threat to global coffee production that in 2014, the US pledged $5 million to research rust-resistant coffee varieties. Thriving in moist, hot conditions, The Climate Institute states that climate change has been responsible for the fungus' spread "to higher altitudes where coffee is grown."
At least, that's what we thought.
A new study from the University of Exeter throws cold coffee on this link between CLR and climate change. Published in the Philosophical Transactions B, the paper states: "We find no evidence for an overall trend in disease risk in coffee-growing regions of Colombia from 1990 to 2015, therefore, while weather conditions were more conducive to disease outbreaks from 2008 to 2011, we reject the climate change hypothesis."
Drop the mic. (Or should that be mocha?)
Studying plantations in Colombia, where coffee production fell by by 40 percent between 2008 and 2011, the Exeter researchers claim that this decrease in yield was actually caused by a "perfect storm" of factors, including changing weather and fertiliser prices.
Study lead author and lecturer in microbial ecology, Dan Bebber explained: "Farmers weren't treating coffee bushes as they normally would, and this was probably one of the factors that led to the rise in CLR. The climate was conducive to CLR but there had been earlier periods of similar conditions when there wasn't an outbreak."
As well as weather and fertiliser, Bebber added that management of coffee plantations and socioeconomic factors could also have impacted yield in Columbia. The study concluded that more research was needed to fully understand the outbreak of coffee rust.
And with around 120 million people in more than 70 countries depending on the global coffee trade to make a living—not to mention those of us who need at least two shots of espresso before any kind of pre-12 AM social interaction—let's hope that research comes soon.