Bitter Brew: the Cost of Climate Change on Coffee

Hashiemen Badal

Student at Monash University, studying BSc (Advanced) Plant Sciences with Genetics and Genomics

Coffee is about to become more bitter and more expensive.That’s because coffee plants are sensitive to temperature and prefer to grow at between 18°C and 28°C^{1, 2, 3} – about the same as a sunny spring or autumn day in Melbourne.

Hotter weather stunts the growth of the coffee plant and accelerates fruit ripening causing more fruit to spoil before it can be hand-harvested. So global warming has prompted coffee growers to find cooler places for their crop to grow.

Their solution? Go uphill.⁴

Higher elevations, such as those nearer the tops of mountains, are cooler and less prone to drought. But reaching these areas can be tough. Farmers have to be extra careful in navigating the slopes of the mountains.⁵ This problem, as well as the capital and labour needed  to establish new orchards at higher altitudes, adds to the cost. And all these added costs are then passed on to consumers. In the coffee culture of Melbourne, this rise in costs will lead to a competitive market and ultimately to shortages and expensive coffee.⁶

‍

Agriculture’s kryptonite

The economic impact of climate change on agriculture is hardly limited to coffee. A single prolonged drought, for instance, can cause a ripple effect in the global food supply. It means your next bowl of salad would cost more.

During the Millennium Drought in Australia (1996-2010)⁷, in which there was record low rainfall and frequent hot weather, the price of vegetables rose by a third. And it almost doubled for fruits between 2005 and 2007.⁸

So we have a crucial agricultural weak spot. When global temperature rises, crops are not well adapted to cope with extreme heat and drought. This will eventually lead to decreased yields, possible food shortages, and increased food costs.

‍

A potential silver bullet

Global warming will affect agriculture worldwide. High temperatures together with limited rainfall create a perfect blend for intense drought.⁹ Lack of water in a hot environment is a major stress factor for crops.

Recent research, however, has shown that bacteria can help crops adapt to these conditions. These studies looked into plant microbiomes - the diverse communities of microorganisms (bacteria and fungi) that live inside and outside plants, and below the ground associated with the roots.¹⁰ All plants have associated microbiomes, and researchers believe that tweaking them can make plants more drought-resistant.

Among the microorganisms, for instance, are beneficial bacteria known as Plant Growth-Promoting Bacteria (PGPB).¹¹ Underground, PGPB help the roots to absorb minerals such as nitrogen, phosphorus, and iron. Above ground, PGPB produce plant hormones that stimulate branching, leafing, and height increase.

The idea behind using PGPB is simple. Bacteria with a desired benefit are grown in a nutrient-rich liquid medium, and then applied to the soil or sprayed on the plant.

In the case of coffee, research has already shown that adding certain PGPB to the growing plants can increase branches and leaves.¹² This is good news since the coffee beans grow on stems and branches. More branches mean more coffee beans.

‍

Fighting fire with fire

Other groups of bacteria living in the Atacama Desert in Chile and in hot springs in India could hold answers to climate change and drought. These bacteria are extremophiles – microorganisms that thrive in extreme conditions (hot, cold, dry, salty and the like).¹³

Their peculiar characteristics can be useful when transferred to plants. If we add heat-tolerant and water-efficient bacteria to plants, for example,  it is possible to make them…well…heat-tolerant and water-efficient.

The microbiome of desert plants is well adapted to drought conditions as they have evolved to thrive in arid conditions.¹⁴ Researchers from Chile isolated seven Bacillus strains from two plants, the small perennial, Metharme lanata Phil. and the Peruvian bell flower, Nolana jaffuelii Johnst.¹⁵

These seven bacterial strains were cultured, then applied to lettuce plants (Lactuca  sativa L.) Out of the seven, two were found to aid plants under drought conditions. They helped the plants store more water and absorb more nitrogen. Ultimately they allowed lettuce to grow when water was limited.

In another study, 123 bacteria samples were collected from plants growing around hot springs in India. The work revealed that some of these bacteria could help plants tolerate heat.¹⁶ When they were added to tomato plants, the result was longer roots and shoots.

Another similar study used bacteria from plants growing around volcanoes in Mexico.¹⁷ Selected bacteria from these plants were added to capsicums and the results were positive. The peppers grew more roots, thicker stems, and bore more fruit than those without the bacteria.

The use of bacteria species from extreme environments for improving plant growth has now been widely studied. Rice, grapes, arugula (rocket), wheat, and other crops have been used as models in the hopes of finding more and more bacteria that can improve the growth properties of crops.

Studies like this are very important. The global population is rising faster than our ability to produce food. Meaning, we will be feeding more people but producing less food.

Moving forward

Victoria may be a leading state in research and development, but it is way behind in terms of crop microbiome research. Despite the influence of agriculture on the state's economy, there has been little focus on studying local PGPB and its application to plants.

But our backyard is home to extreme conditions. Plants from the Australian Outback could host bacteria significant to the future of agriculture.

Much remains unknown about PGPB, however. Microbiomes are complex environments, interactive, and not fully understood, especially with respect to the impact that consuming PGPB-treated crops might have on the human microbiome.

While we cannot predict the future with certainty, our current trajectory suggests significant challenges ahead. The ripple effects of global warming on agriculture will make food production increasingly difficult, impacting both the availability and affordability of everyday staples. advancements in plant microbiome research, however, offer a glimmer of hope.

As more bacteria are studied for their applications in farming, there is a chance that future food production will rely heavily on these microscopic allies. In the near future, your food might be grown with the help of bacteria, ensuring sustainable yields despite the challenges posed by climate change.

‍

References

1. Scott, M. (2015). Climate & Coffee, NOAA Climate.gov. www.climate.gov/news-features/climate-and/climate-coffee

2. Myhrvold, N. & Coste, R. (2023). Coffee production: Description, cultivation, processing, hulling & facts, Britannica www.britannica.com/topic/coffee-production 

3. Bilen, C., et al. (2022). A systematic review on the impacts of climate change on coffee agrosystems. Plants, 12 (1): 102.  doi.org/10.3390/plants12010102 

4. Ahmed, S., et al. (2021). Climate change and coffee quality: Systematic review on the effects of environmental and management variation on secondary metabolites and sensory attributes of Coffea arabica and Coffea canephora. Frontiers in Plant Science, 12. doi.org/10.3389/fpls.2021.708013 

5. The Great Coffee Project. (undated). New Heights: the Challenges and Benefits of Coffee Farming at High Altitude. The Great Coffee Project. https://thegreatcoffeeproject.com/blogs/inside-the-great-coffee-project/new-heights-the-challenges-and-benefits-of-coffee-farming-at-high-altitude 

6. The Economic Times. (2023). Bitter coffee prices: A worldwide bean shortage is making coffee lovers sweat espresso bullets. The Economic Times https://economictimes.indiatimes.com/industry/cons-products/food/bitter-coffee-prices-a-worldwide-bean-shortage-is-making-coffee-lovers-sweat-espresso-bullets/articleshow/102557109.cms?from=mdr 

7. Heberger, M. (2012). Australia’s Millennium Drought: Impacts and Responses. The World’s Water, 17 (2): 97–125.  https://link.springer.com/chapter/10.5822/978-1-59726-228-6_5 

8. Murphy, M., et al. (2022). The resilience of Melbourne’s food system to climate and pandemic shocks. University of Melbourne. https://doi.org/10.46580/124370

9.National Oceanic and Atmospheric Administration & National Integrated Drought Information System. (n.d.). Flash Drought. Drought.gov; National Integrated Drought Information System. https://www.drought.gov/what-is-drought/flash-drought 

10. Dastogeer, K. M. G., et al. (2020). Plant microbiome–an account of the factors that shape community composition and diversity. Current Plant Biology 23: 100161.  https://doi.org/10.1016/j.cpb.2020.100161 

11. Olanrewaju, O. S., et al. (2017). Mechanisms of action of plant growth promoting bacteria. World Journal of Microbiology & Biotechnology 33 (11).  https://link.springer.com/article/10.1007/s11274-017-2364-9 

12. Urgiles-Gómez, N., et al. (2021). Plant growth-promoting microorganisms in coffee production: From isolation to field application. Agronomy, 11 (8): 1531. https://www.mdpi.com/2073-4395/11/8/1531

13. Gabrielli, A. (2023). Extremophiles 101. Education.nationalgeographic.org; National Geographic. https://education.nationalgeographic.org/resource/extremophiles-101/ 

14. Makhalanyane, et al. (2015). Microbial ecology of hot desert edaphic systems. FEMS Microbiology Reviews 39 (2): 203–221. doi.org/10.1093/femsre/fuu011 

15. Santander, C., et al. (2024). Enhancing water status and nutrient uptake in drought-stressed lettuce plants (Lactuca sativa L.) via inoculation with different Bacillus spp. isolated from the Atacama Desert. Plants 13 (2): 158. doi.org/10.3390/plants13020158 

16. Patel, et al. (2017). Characterization of culturable bacteria isolated from hot springs for plant growth promoting traits and effect on tomato ( Lycopersicon esculentum ) seedling. Comptes Rendus Biologies 340 (4): 244–249. doi.org/10.1016/j.crvi.2017.02.005 

17. Clara Ivette Rincón-Molina, et al. (2022). Bacterial community with plant growth-promoting potential associated to pioneer plants from an active Mexican volcanic complex. Microorganisms 10 (8): 1568–1568.  doi.org/10.3390/microorganisms10081568 

18. Banner image by Nathan Dumlao at Unsplash