The Robusta coffee is sensitive to global climate change: its temperature optimum is in the range of 18.6-26.6 degrees Celsius, not 22-30 degrees Celsius, as previously thought. According to the study, published in the journal Global Change Biology, the increase in air temperature by one degree Celsius leads to a decrease in grain yield of at least 14 percent.
Most of the world’s coffee crop are just two varieties — Coffea Arabica and Coffea canephora (Arabica and Robusta). Traditionally, researchers have been more concerned about the prospects of growing Arabica in the context of global climate change — this has occurred from the cool highlands of the Arabian Peninsula, with average annual temperatures of 18-23 degrees Celsius and is sensitive to overly warm conditions. In contrast, the Robusta variety is considered resistant to hot climate, because historically, this species evolved in the lowlands of the valley of the Congo river in Central Africa, where the average annual temperature range did not fall below 22 to 30 degrees Celsius. However, it is important to remember that agriculture is not so much the survival of plants and their ability to vegetative growth (which in the case of Robusta are possible with a larger range of temperatures), how effective fruiting.
Scientists under the leadership of Kata Jarrod (Jarrod Kath) from the University of southern Queensland investigated the impact of warming on the growth, flowering and fruiting Robusta. For this purpose they used data on harvest for 10 years with 798 farms in Indonesia and Vietnam (these two countries hold 55 percent of the global production of Robusta coffee), and climatic database ERA5 and TerraClimate, which allowed to track air temperature and rainfall in the selected time period.