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Climate Change Impacts on the Growth and Yield of Coffee

Paper Reviewed
DaMatta, F.M., Rahn, E., Läderach, P., Ghini, R. and Ramalho, J.C. 2019. Why could the coffee crop endure climate change and global warming to a greater extent than previously estimated? Climatic Change 152: 167-178.

Coffee is one of the most popular beverages, consumed by approximately one-third of the global population. It is grown in some 80 tropical countries and provides economic stability for some 25 million farmers and their families.

Recently, there has been a growing interest in how this crop species might respond to predictions of future climate change. In this regard, DaMatta et al. (2019) note that "climate change scenarios have predicted remarkable effects on the coffee crop including extensive reductions in agro-climatic zoning and losses (and drift) of suitable areas in most coffee-producing countries." They also envision "decreases in crop yields, beverage coffee quality, negative impacts on wild populations of Coffea Arabica, greater pest incidence, and increased agricultural, social, and economic vulnerabilities." In short, the predictions amount to nothing short of doom and gloom for the future of this important species.

But is such really the case? Is this future set in stone?

According to a recently published review paper by DaMatta et al., the answer is a resounding no! The reason, they say, is because the "pessimistic [projections] have not considered the potential positive effects of elevated atmospheric carbon dioxide concentration [CO2] on coffee photosynthesis and leaf retention or the role of CO2 as a key player in coffee heat tolerance." Nor have they considered "the recognized resilience of elite coffee genotypes to acclimate to stressful conditions."

With respect to the positive effects of atmospheric CO2 enrichment on coffee plants, DaMatta et al.'s literature review led to the following key findings:
1. There is "unequivocal evidence that elevated CO2 stimulates [coffee] photosynthesis and crop yield."
2. The observed photosynthetic enhancement of elevated CO2 on coffee is sustained across time, i.e., "coffee plants do not show any evident sign of photosynthetic downregulation" or acclimation.
3. Coffee plants "use more light under elevated CO2 and are less prone to suffer from oxidative stress."
4. Plant growth and crop yields are enhanced under elevated CO2. The mean crop yield in a 3-year FACE study was enhanced by 28% in response to a 160 ppm increase in atmospheric CO2.
5. Elevated CO2 mitigates the negative impacts of high temperature on coffee growth.
6. Elevated CO2 does "not promote noticeable changes in bean quality traits," yet has been shown to mitigate certain biochemical modifications caused by excessive heat.

In light of the above findings gleaned from the scientific literature, DaMatta et al. conclude their review by noting that the information they present points toward "a more optimistic scenario than the previous catastrophic estimates of the impact of climate change on coffee production." And this positive future, courtesy of rising atmospheric CO2, is great news for those who grow and consume this crop!

Posted 5 April 2019