Climate change and coffee: what Vietnam's Central Highlands are facing
Long heatwaves, rain out of season, water running short: climate change is already in every coffee garden in the Central Highlands. What does science say about how climate affects the coffee tree, and what can growers do starting today?
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The 2024 dry season is one many growers in Vietnam's Central Highlands will not forget. The heat went on for weeks, and in many places water for irrigation ran short just when the coffee trees needed it most. That same year, Robusta prices on the London exchange set one record after another, partly because the market was worried about supply from Vietnam.
Climate change is no longer a topic only for international conferences. It is already in every coffee garden, in every flowering and every harvest. This article sums up what science knows about how climate affects the coffee tree, and what growers can do starting today.
Coffee is more sensitive to climate than we think
Arabica likes it cool, which is why it is grown in highland areas such as Cầu Đất near Đà Lạt. Robusta has long been seen as the "tougher" species, better able to take the heat, and it is the main crop of the Central Highlands.
A study published in 2020 in Global Change Biology changed that view. Researchers analysed ten years of yield data from 798 Robusta farms in Vietnam and Indonesia. They found that Robusta yields best at a mean annual temperature below 20.5 °C, much cooler than the 22–30 °C long considered ideal. For every 1 °C above that point, yields fell by about 14%.
At the global scale, a 2015 study in Climatic Change projected that the area of land suitable for coffee could shrink by about half by the middle of this century if the industry does not adapt. Low latitudes and low altitudes are hit hardest, and Brazil and Vietnam, the world's two largest producers, are among them.
Three changes growers see most clearly
1. Hotter, harsher dry seasons. High temperatures make trees lose water faster, so they need more irrigation. In severe drought years such as 2016 and 2024, many reservoirs and wells ran dry early, irrigation costs rose and trees were weakened.
2. Erratic rain. Robusta needs a dry spell followed by enough water to flower all at once. When rain comes out of season, the trees flower in several scattered rounds, the cherries ripen unevenly and the harvest drags on. Picking only ripe cherries becomes harder, and so does keeping the quality of the beans consistent. Heavy rain at harvest time also makes drying difficult and raises the risk of mould.
3. Shifting pests and diseases. Hot, humid weather suits some pests and diseases. Studies in East Africa and Indonesia show that the coffee berry borer breeds faster and turns up at higher altitudes as temperatures rise.
What growers can do in the garden now
The good news is that growers are not standing still. Many practices are already in use across the Central Highlands and have proved their worth:
- Shade trees and intercropping. Durian, avocado, macadamia or pepper planted among the coffee keep the canopy cooler and the soil moist for longer. They also give the farm another income when coffee prices fall.
- Water-saving irrigation. Drip or under-canopy sprinklers, watering at the right time instead of flooding the ground. Mulching with dry leaves or coffee husks keeps moisture in the soil.
- Healthy soil. Organic fertiliser, ground cover instead of bare soil around the trees, and erosion control on slopes. Soil rich in organic matter holds water better through the dry season.
- Replanting with better varieties. Replacing ageing trees with high-yielding grafted clones bred by the Western Highlands Agro-Forestry Scientific Institute (WASI), such as TR4 and TR9.
- Keeping records. Tracking water, fertiliser and yield year by year shows growers what works. It is also the basis for joining certification programmes.
Why international buyers care
The world's large roasters need a stable supply over many years, and many have committed to cutting emissions across their supply chains. So they favour growing areas with sustainable farming practices. Certifications such as 4C and Rainforest Alliance include criteria on water use, soil care and forest protection.
The European Union's Deforestation Regulation (EUDR) goes a step further: coffee sold into the EU must be shown not to come from land deforested after 31 December 2020, with the location of each farm. Forests are not only a buyer's requirement. They hold water and regulate the climate of the coffee-growing areas themselves.
Phuoc Son alongside the growers
Phuoc Son works directly with more than 5,000 farming families. Every farm that supplies coffee to Phuoc Son is located by GPS, and every farm over 4 hectares is mapped with its boundary, by the company's own field team. This is the basis for proving origin to buyers, and for following each farm with its growers season after season.
Through 4C workshops, Phuoc Son shares sustainable farming practices with growers: using water sparingly, caring for the soil, and applying fertilisers and crop protection safely. The climate is changing, but well-tended coffee gardens will stand firm for longer.
From the grower's hand to the drinker's heart. Keeping coffee gardens healthy in a changing climate is how that journey continues.
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