The latest UN Emissions Gap Report projects that if countries follow through on current pledges to reduce carbon emissions, average global temperatures could rise by 2.6 to 2.8°C (4.7 to 5.0°F) this century, compared to pre-industrial levels. But it’s important to note that this increase is an average across the globe. On land, where most fresh fruit is grown, temperatures will likely increase even more sharply. Generally, temperature increases on land—especially in non-tropical areas—are expected to be about double the global average.
For example, data from the National Oceanic and Atmospheric Administration (NOAA) shows that in 2023, the average temperature on land was already 1.8°C (3.2°F) higher than the 1901–2000 average, while ocean temperatures were 0.91°C (1.6°F) higher. Projections indicate that by the end of the century, temperatures on land could rise between 5.2 and 5.6°C (9.4 to 10.1°F). Such increases could have drastic effects, even if they might seem modest at first glance, especially given that daily temperature swings can be much larger. But even a seemingly small, steady rise in temperature—barring any of the more uncertain, abrupt changes that could be brought on by crossing tipping points in the climate system such as through melting ice sheets or deforestation—can have major consequences for crops that depend on specific climate conditions to thrive.
How Rising Temperatures Affect Fresh Fruit Crops
There are many ways that a shifting climate can impact fresh fruit crops. Two of the main temperature-related ones that have become apparent in recent seasons are pushing temperatures beyond certain critical limits and increasing cumulative heat over the entire growing season.
- Exceeding Temperature Limits
Plants have specific temperature ranges in which they grow best. When temperatures rise too high, they can push plants beyond these limits. For example, grapevines grow best between 25 and 35°C (77 and 95°F). If temperatures go much higher, the plants can become stressed. During the summer of 2024, temperatures in Bakersfield, CA, frequently exceeded this range, with several stretches above 100°F (38°C). Extreme heat can cause plants to shut down important processes like photosynthesis, which is essential for plant growth and fruit production. When plants are stressed by high temperatures, they may close the tiny openings on their leaves, called stomata, to conserve water. This reduces their intake of carbon dioxide, preventing them from producing energy, which can slow or halt growth.
- The Impact of Cumulative Heat (Growing Degree Days)
Besides extreme temperatures, the build-up of heat over time also affects crops. Farmers track “growing degree days” (GDDs) to measure cumulative heat during the growing season. More GDDs mean that plants go through stages like flowering, fruit set, and ripening more quickly. For some crops, faster development might seem like a good thing, allowing for earlier harvests when market prices are high. However, accelerated growth has major downsides.
For table grapes, GDDs begin accumulating after the plants are pruned. As the season progresses, GDDs track how much heat the plants receive, influencing stages like flowering and ripening. The problem with too many GDDs is that plants and fruit develop faster, leaving less time for each growth stage. This can impact both the volume and quality of the fruit. For example, faster ripening reduces the time for fruit to increase in size and accumulate sugars, affecting its taste, texture, and market appeal.
In Piura, Peru, a rise in growing season temperatures by 4°C (7.2°F) led to smaller grapes in some cases, with fruit reaching only about two-thirds of its normal size and weight. This led to a 30% decrease in production volume. Although Piura’s unusual temperatures were partly due to an El Niño event, scientists warn that other regions could face similar conditions as global warming continues.
- Other Temperature-Related Impacts
Growing systems are complex, and temperature thresholds and cumulative heat are not the only ways warming will affect plants. While an exhaustive review is outside the scope of this article, some of the other temperature-related effects worth mentioning are chilling hours and pests and disease. Plants need a certain number of cumulative hours below a certain temperature and above 0°C (32°F) to produce a healthy crop. Higher winter and early spring temperatures can decrease yields. Elevated temperatures over a longer part of the growing season may also increase the risk of pest and disease outbreaks. Additionally, changes in the timing of fruiting may coincide with periods when pests are more abundant. Finally, greater climate stress may make plants more susceptible to attack.
Other Risks of Faster Growth Cycles
As fruit plants mature faster, they become more exposed to unpredictable weather. An early bloom, for example, might lead to a greater risk of frost in spring or increased vulnerability to rain, both of which can damage developing flowers or fruits. These faster cycles, resulting from higher GDDs, can be especially problematic for regions with volatile weather, where sudden frosts or rainstorms could destroy a year’s worth of crop investment in a matter of days.
On a larger scale, this can also disrupt global fruit supply chains. When crops ripen earlier, the supply timing shifts, which can create mismatches in demand and pricing. While early-season fruit can fetch higher prices, this benefit may be offset by reduced quality or smaller harvests. In turn, this can affect the fruit export market, influencing prices and availability in other countries.
Adaptation Strategies for Growers
Facing higher temperatures and unpredictable weather, fruit growers are experimenting with several strategies to adapt:
- Using Shade Nets to Protect Crops
Shade nets help reduce the temperature around plants, protecting them from the worst of the summer heat. They also cool down winter temperatures to ensure plants accumulate enough chilling hours. These nets are already used in regions like Chile’s Central Valley to protect cherries and other fruit. Shade nets can provide a buffer, lowering ambient temperature and helping to promote productivity and preserve fruit quality. However, the installation and maintenance of these nets increase production costs.
- Developing Heat-Resistant Varieties
Research organizations and seed companies are working on developing fruit varieties that can withstand higher temperatures and drought. There may, however, be biological trade-offs preventing plant breeders from achieving both high yields and greater climate resilience through traditional plant crossings. It may be possible to overcome these challenges with genetic modification, although these varieties may be unacceptable in markets such as the European Union. Regardless of which methods are used, new varieties may come with added costs, either through increased investment in breeding programs or royalties for growers who want to use these improved plants.
- Moving Production to Cooler Regions
In more extreme cases, some growers may consider moving fruit production to higher elevations or more northern locations where temperatures are cooler. A recent study in Nature Reviews Earth & Environment found that up to 90% of traditional wine regions in southern Europe and California could disappear by 2100 if warming trends continue. This could prompt a shift toward cooler areas, like the Pacific Northwest or northern Europe, which might become more suitable for fruit cultivation in the future. Such relocations would come with significant costs, both for the growers and the communities affected by these moves.
Why Adaptation Alone May Not Be Enough
While these adaptation measures offer some relief, they come with limitations and costs. The emphasis in this article has been on the effects of rising temperatures, but there are also the related impacts of changing precipitation patterns to consider. Rising temperatures will likely bring more extreme weather, not just heat but also unpredictable rain, storms, and droughts. For example, in 2023, Hurricane Hilary struck California during the peak of the grape harvest, reducing production from an average of 92 million boxes to 73 million boxes—a 20% drop. Similar to shade nets, plastic covers can shelter plants from rain or hail, although they also come with costs and may increase the risk of disease by elevating temperature and moisture. Water cuts such as the ones being imposed in some areas of southern Spain, which is in the midst of a six-year drought, are much harder to protect against. Even with canopy covers and heat-resistant varieties, extreme weather events can have major impacts on production levels and prices.
If no further action is taken to reduce carbon emissions, the fresh fruit industry could see a future of shrinking harvests, higher prices, and increased instability. In addition to rising costs for consumers, there could be wider economic impacts, as the agriculture industry is linked to various other sectors.
The Bigger Picture: Fresh Fruit as a Climate Indicator
The fresh fruit industry might be among the first sectors to feel the full impact of global heating, acting as a “canary in the coal mine” for other industries. With its high exposure to temperature changes and weather extremes, the fruit industry has a unique opportunity to lead the way in developing sustainable practices. Practices such as regenerative agriculture, which improves soil health and resilience, and precision farming, which optimizes water and resource use, are two promising approaches. By pioneering these methods, the fresh fruit industry could serve as an example for other agricultural sectors and industries beyond agriculture.
However, it is also important to recognize that growers are facing rising costs and shrinking margins not only because of a shifting climate, but also because of greater labor, input, and logistics costs, as well as higher interest rates and difficulty accessing credit. Consumers are likewise facing a related cost of living crisis. There may be some “win-wins” with solutions such as regenerative agriculture and precision farming, although there may also be some inevitable trade-offs.
Two common suggestions for dealing with these costs are tax cuts to increase the overall size of the economy or higher taxes to redistribute wealth from better-off parts of the economy to the parts under greater strain. Whichever policy you prefer, producers and consumers are going to need help shouldering the costs of climate adaptation and mitigation. And it’s not just more money that the fresh fruit industry is going to need. It is also going to require collaboration across sectors. Reducing the risks associated with global heating will involve partnerships with policymakers, scientists, and technology developers. If given the right support, the fruit industry could play a major role in reducing carbon emissions and building resilience to climate impacts.
In the end, the challenges posed by global heating go beyond just the fresh fruit industry. As temperatures continue to rise, society may face even larger challenges. But by addressing these issues early, the fresh fruit industry could help pave the way toward a more sustainable and resilient future, demonstrating that effective action on global heating is possible and beneficial for all.
- Adam Formica is the head of research at Sensonomic, an Oslo, Norway-based software services provider.
