Disappearing winters and how farmers in South America are coping
By Alison Smart — September 30, 2025
3 MIN READ
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Sign up hereIn 2024, olive producers across Peru saw their harvests disappear. Trees that had produced olives for centuries – some planted 450 years ago by Spanish colonists – suddenly bore almost no fruit. In Chile, olive oil production decreased by approximately 30% compared to 2023, reaching the lowest level since 2016. The trees looked healthy and strong. There were no pests, no diseases, no obvious problems. Yet production plummeted.
The culprit was rising temperatures that disrupted the delicate seasonal rhythms olive trees depend on. In Peru’s desert regions, warmer winters prevented trees from getting the cold hours they need to flower. In Chile’s Mediterranean valleys, higher temperatures accelerated snowmelt, reducing water availability during critical growing periods. The same warming trend created different crises depending on local conditions.
The changing climate presents a real challenge for olive oil producers, however, many of them are meeting it with adaptability and innovation. From monitoring technology to learning from ancient tree genetics, to high-altitude experiments, farmers are developing adaptation strategies that could inform olive oil production in a changing climate around the world.
When Winter Warming Disrupts Irrigation
Chile’s producers face a water crisis rooted in winter warming. The country’s olive groves depend in part on snowpack in the Andes Mountains. This snowpack provides natural water storage, accumulating snow during winter and melting slowly through spring and summer when trees in the valleys below need irrigation. Warmer temperatures result in precipitation that falls as rain instead of snow, and the snow that does accumulate melts earlier and faster, leading to reduced groundwater. The result is less water for irrigation during the crucial growing season. Probable Futures’s “Change in snowy days” map depicts this trend throughout the Andean range, showing that some areas could lose over a month of snowy days at 3°C of warming.
“Water availability is the most visible impact on production,” explains Pamela González of ChileOliva, the country’s olive oil trade association. Chile’s Mediterranean climate once had consistently rainy winters and dry summers, but climate change is disrupting these patterns.
According to González, producers are responding by developing “smart” irrigation methods that use monitoring technology, weather data, and sensors to optimize water use – a solution that addresses both climate resiliency and longer term sustainability of water resources. Chilean producers have also developed a state certification for sustainable olive oil production that includes specific goals and concrete climate adaptation and mitigation actions.
That said, it is clear to González and the producers she works with that there are limitations to these solutions, both financially and climatically. “The only obstacles we can mention [come from] the speed of climate change…as changes are increasingly rapid, and we are always racing against time. It requires constant training and the adoption of technologies that are often expensive to implement or require specialized professionals to use.”
When Trees Can’t Get Cold Enough
“The most pressing issue [for olive oil producers] today is the sustained rise in winter temperatures, which drastically reduces the accumulation of chill hours required for floral induction,” explains Gianfranco Vargas, Founder of Sudoliva, an initiative to safeguard the heritage of olive trees in Central and South America. While the trees in this desert region always managed extreme water scarcity, they have evolved to rely on predictable winter cold. Even slight increases in winter temperatures can disrupt the biological processes that determine whether trees will produce – a process called “chill hours”.
Chill hours are defined as the amount of time a fruit tree (such as the olive tree) needs to be exposed to cold temperatures in order to bear fruit. These chill hours lead into and out of a tree’s dormant period during the coldest winter temperatures. When warmer temperatures arrive, it signals to the plant that it is time to break dormancy and start producing fruit. Without the necessary number of chill hours, the plant won’t receive that signal to start producing. Lack of chill hours adds stress to the plant, leading to a delay in budding, reduced flowering, and poor fruit development.
Olive trees generally need between 300 and 600 consecutive chill hours, or about two to three weeks, below 7°C (45°F). In 2024, global warming, combined with an unusually strong El Niño, resulted in too few chill hours in Peru, leading to the poorest harvest in producer’s recent memory. As reported by Olive Oil Times, Vargas noted: “my production will not even reach 12 or 13 percent of what it normally would”.
Adapting to a Warming World
The earth’s global average temperature is now around 1.5°C warmer than it was when the oldest olive groves were planted, which means that producers can expect lack of chill hours to be recurrent. However, some farmers are already anticipating this trend, and have begun to implement adaptive techniques: some are moving groves to higher altitudes, others are shifting to varieties of trees that are more resilient and/or require fewer chill hours, and some are using a process called “girdling”, which involves removing a thin strip of bark around a branch or trunk, temporarily interrupting the flow of nutrients and forcing the tree to redirect resources toward flowering and fruit development.
Vargas thinks that the region’s oldest olive trees are becoming the most valuable resources for climate adaptation in olive oil production. His research has identified heritage varieties that naturally handle challenging conditions better than modern ones. However, new trees take 3-5 years to produce fruit, so farmers need both quick fixes like girdling and long-term strategies based on these resilient ancient varieties.
Vargas points out similar challenges to those experienced by González and the Chilean Producers: “the main obstacle remains the lack of attention from both academia and the government. All these adaptation efforts – whether varietal change, girdling, or relocating plantations – have been led by the farmers themselves. Institutional support is urgently needed, as not all growers have the financial capacity or willingness to invest in long-term adaptation strategies.”
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