Robusta coffee has lower heat tolerance than expected

In a new study from the International Center for Tropical Agriculture, experts have discovered that the optimal temperature range for robusta coffee production is much lower than previously thought. According to the researchers, the heat tolerance of the plant that produces robusta coffee has been consistently overestimated. 

The study revealed that just a slight increase in temperature beyond the optimal range for the robusta coffee plant can cause yields to plummet. The findings suggest that the future may be tough for the coffee industry.

The researchers analyzed 10 years of yield observations among nearly 800 farms in Southeast Asia. The analysis showed that the optimal temperature range for robusta is 20.5 degrees Celisius, which is much lower than expected. The researchers also determined that for every one-degree increase over the optimal range, yields dropped by 14 percent.

“Our results suggest that robusta coffee is far more sensitive to temperature than previously thought,” wrote the study authors. “Its production potential could decline considerably as temperatures increase under climate change, jeopardizing a multibillion-dollar coffee industry and the livelihoods of millions of farmers.”

The research was conducted on farms in Vietnam and Indonesia, which supply about half of the world’s robusta beans.

The results differ from current estimates that are based on explorations in Central Africa.

“This should make us reassess the viability of some of our current options, like switching from arabica to robusta coffee as the climate warms to adapt production to climate change,” said Jarrod Kath, the study’s lead author from USQ.

Arabica coffee, which has a more highly preferred taste, is even more sensitive to temperatures than robusta. Coffee farmers around the tropics have been replacing their arabica trees with robusta trees, and arabica farmers have been searching for better locations to maintain production.

“Precipitation changes have long been a concern of the coffee industry,” said study co-author Laurent Bossolasco. “Now it’s clear that we need more in-depth analysis of temperature variations in the robusta region.”

The study is published in the journal Global Change Biology.

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By Chrissy Sexton, Earth.com Staff Writer