Climate change is one of the most significant challenges facing agriculture today, and its effects are particularly pronounced in regions that rely heavily on rainfed farming.
In Tunisia, where agriculture is a cornerstone of the economy and food security, the impact of climate change on rainfed durum wheat production is a growing concern.
A recent study published in the Journal of Cleaner Production provides a detailed analysis of how climate change will affect durum wheat yields in Tunisia and offers sustainable adaptation strategies to mitigate these effects.
The Importance of Durum Wheat in Tunisia
Durum wheat (Triticum durum) is a staple crop in Tunisia, particularly for small-scale farmers. It is primarily grown under rainfed conditions, meaning it depends entirely on rainfall for water.
Rainfed agriculture accounts for approximately 60% of Tunisia’s cereal production, and durum wheat alone provides around 70% of the nation’s wheat needs. Despite its importance, Tunisia is not self-sufficient in wheat production and relies on imports to meet its demand.
This reliance makes the country vulnerable to global market fluctuations and the adverse effects of climate change.Rainfed agriculture refers to farming that relies solely on rainfall for water, without the use of irrigation.
It is common in regions where water resources are limited, and it is highly vulnerable to changes in rainfall patterns and drought. Durum wheat, a type of wheat used primarily for making pasta, couscous, and other traditional foods, is highly valued for its high protein content and strong gluten.
In Tunisia, durum wheat is not only a dietary staple but also a critical source of income for small farmers.Climate change is expected to bring higher temperatures, reduced rainfall, and more frequent extreme weather events such as droughts and floods.
These changes could severely impact rainfed wheat production, threatening food security and the livelihoods of small farmers. The study aims to understand how climate change will affect durum wheat yields in Tunisia and identify sustainable adaptation strategies to ensure future food security.
Methods and Approach
The research combined field experiments and computer modeling to predict the effects of climate change on rainfed durum wheat production. The study used the AquaCrop model, a tool developed by the Food and Agriculture Organization, to simulate crop growth, water use, and yield under different climate scenarios.
The researchers also used climate data from the Med-CORDEX initiative, which provides detailed projections of future climate conditions in the Mediterranean region.AquaCrop is a crop simulation model developed by the FAO to predict crop yield, water use, and productivity under different environmental conditions.
It is particularly useful for assessing the impacts of climate change on agriculture and for developing adaptation strategies. Med-CORDEX (Mediterranean Coordinated Regional Climate Downscaling Experiment) is an initiative that provides high-resolution climate projections for the Mediterranean region.
It uses regional climate models (RCMs) to simulate future climate conditions based on different greenhouse gas emission scenarios.The study focused on two future time periods: 2040–2050 (mid-term) and 2080–2090 (long-term). It also considered two climate scenarios: RCP 4.5 and RCP 8.5.
These scenarios represent different levels of greenhouse gas emissions and their potential impacts on the climate. RCP stands for Representative Concentration Pathways, which are scenarios used to project future climate change based on different levels of greenhouse gas emissions.
RCP 4.5 represents a moderate emissions scenario where global temperatures are expected to rise by about 2.4°C by the end of the century, while RCP 8.5 represents a high-emissions scenario with a projected temperature rise of 4.3°C.
The research was conducted in the Beja region of northwestern Tunisia, a major area for rainfed durum wheat production. Field experiments were carried out over three growing seasons (2016–2019) to collect data on soil moisture, crop growth, and yield.
Yield Gaps and Reduced Productivity
The study also examined the yield gap, which is the difference between the maximum potential yield and the actual yield achieved by farmers. The yield gap is expected to increase significantly under climate change, reaching 55% by the end of the century under the RCP 8.5 scenario.
This means that even with optimal farming practices, farmers will struggle to achieve high yields due to the adverse effects of climate change.
What is Yield Gap?
The yield gap is the difference between the maximum potential yield (what could be achieved under ideal conditions) and the actual yield (what farmers achieve in practice). A large yield gap indicates that there is significant room for improvement in crop productivity.
How Climate Change Will Affect Durum Wheat
The study revealed several critical insights into how climate change will impact rainfed durum wheat production in Tunisia. One of the most significant impacts of climate change is the rise in temperatures.
The study found that by the end of the 21st century, the average temperature in the Beja region could increase by 4°C under the high-emissions scenario (RCP 8.5).
This rise in temperature will shorten the growing season of durum wheat by 5 days per decade, meaning the crop will have less time to grow and produce grain.The growing season is the period during which crops are able to grow and develop.
It is influenced by factors such as temperature, rainfall, and daylight hours. A shorter growing season can reduce the time available for crops to reach maturity, leading to lower yields.
Higher temperatures also accelerate the crop’s growth cycle, reducing the time available for biomass accumulation and grain formation. This could lead to lower yields, as the crop will not have enough time to reach its full potential.
The study found that for every 1°C increase in mean temperature, durum wheat yields could decrease by 2.5% to 7%, depending on the severity of the temperature rise.Rainfall is expected to decrease significantly in the coming decades.
The study projected a 37% reduction in precipitation by the end of the century under the RCP 8.5 scenario. This reduction in rainfall will exacerbate water scarcity, making it harder for rainfed wheat to thrive.
Drought, a period of abnormally low rainfall, is already a common occurrence in Tunisia, and climate change is expected to make droughts more frequent and severe.
The study found that the number of years requiring irrigation could increase from 3 years in the baseline period (2009–2020) to 9 years by the end of the century under the RCP 8.5 scenario.
This means that farmers will need to rely more on irrigation to sustain their crops, which could be challenging given the limited water resources in the region.As rainfall decreases and temperatures rise, the demand for irrigation will increase.
The study found that the total irrigation requirement for durum wheat could rise from 223 mm in the baseline period to 736 mm by the end of the century under the RCP 8.5 scenario.
This increase in irrigation demand will put additional pressure on Tunisia’s already limited water resources, making it harder for farmers to maintain their crops.
Irrigation, the artificial application of water to crops to supplement rainfall, is essential in regions where rainfall is insufficient to meet the water needs of crops. However, irrigation can be costly and requires access to reliable water sources.
The study also examined the yield gap, which is the difference between the maximum potential yield and the actual yield achieved by farmers. The yield gap is expected to increase significantly under climate change, reaching 55% by the end of the century under the RCP 8.5 scenario.
This means that even with optimal farming practices, farmers will struggle to achieve high yields due to the adverse effects of climate change. The yield gap is the difference between the maximum potential yield (what could be achieved under ideal conditions) and the actual yield.
A large yield gap indicates that there is significant room for improvement in crop productivity.One of the key adaptation strategies explored in the study is adjusting the sowing date of durum wheat.
The researchers found that delaying the sowing date could help mitigate some of the negative impacts of climate change. For example, under the RCP 8.5 scenario, the optimal sowing date shifted from mid-September in the baseline period to mid-December by the end of the century.
However, even with this adjustment, the study found that yield losses would still be significant, highlighting the need for additional adaptation strategies. The sowing date is the date on which seeds are planted in the soil.
Adjusting the sowing date can help farmers avoid extreme weather conditions during critical growth stages, such as flowering and grain formation.
Adaptation Strategies
The study emphasizes the importance of developing sustainable adaptation strategies to ensure the resilience of rainfed durum wheat production in Tunisia. Shifting the sowing date can help farmers avoid the most extreme heat and drought conditions during critical growth stages.
However, the study found that this strategy alone is not enough to fully mitigate the impacts of climate change. Farmers will need to combine this approach with other adaptation measures.Given the increasing demand for irrigation, improving water management practices will be crucial.
This could include investing in more efficient irrigation systems, such as drip irrigation, and promoting water-saving techniques like mulching and conservation tillage.
Additionally, policymakers should prioritize the development of water storage and distribution infrastructure to ensure that farmers have access to reliable water sources. Drip irrigation is a water-saving technique that delivers water directly to the roots of plants through a network of tubes and emitters.
It reduces water waste and improves water use efficiency.Another important adaptation strategy is the development of climate-resilient durum wheat varieties. These varieties should be able to withstand higher temperatures, drought, and other climate-related stresses.
Research institutions and agricultural organizations should focus on breeding and promoting these varieties to help farmers adapt to changing conditions. Climate-resilient crops are varieties that have been bred or genetically modified to withstand extreme weather conditions, such as drought, heat, or flooding.
These crops are essential for ensuring food security in the face of climate change.Sustainable farming practices, such as crop rotation, intercropping, and organic farming, can help improve soil health and reduce the vulnerability of crops to climate change.
These practices can also enhance water use efficiency and reduce the need for chemical inputs, making farming more sustainable in the long term. Crop rotation is the practice of growing different crops in the same area in sequential seasons.
It helps improve soil fertility, reduce pest and disease pressure, and enhance water use efficiency.Finally, the study highlights the need for strong policy support to help farmers adapt to climate change.
This could include providing financial incentives for adopting sustainable practices, investing in research and development, and creating early warning systems for extreme weather events.
Conclusion:
The study provides a clear picture of the challenges that climate change poses to rainfed durum wheat production in Tunisia. Rising temperatures, reduced rainfall, and increased drought will make it harder for farmers to grow this vital crop, threatening food security and livelihoods.
However, the research also offers hope by identifying several adaptation strategies that can help mitigate these impacts.Adjusting sowing dates, improving water management, developing climate-resilient crop varieties, and promoting sustainable farming practices are all essential steps toward building a more resilient agricultural system.
While the study focuses on Tunisia, its findings have broader implications for other regions that rely on rainfed agriculture. As climate change continues to affect food production worldwide, the lessons learned from this research can help guide adaptation efforts in other vulnerable areas.
Power Terms
1. AquaCrop Model
The AquaCrop model is a computer tool created by the Food and Agriculture Organization (FAO) to simulate how crops grow under different water conditions. It predicts crop yields by considering factors like soil moisture, weather, and farming practices. In the study, AquaCrop helped estimate how durum wheat in Tunisia would respond to future climate changes, such as higher temperatures or less rainfall. For example, it calculated how much irrigation water would be needed to maintain yields. The model uses inputs like canopy cover (how much ground the plant leaves cover) and soil data to make these predictions.
2. Med-CORDEX
Med-CORDEX is a set of regional climate models focused on the Mediterranean region. These models provide detailed projections of future climate conditions, such as temperature and rainfall, at a local scale. In the study, Med-CORDEX data helped predict how Tunisia’s climate might change by 2050 or 2100. This was crucial for understanding how droughts or heatwaves could affect wheat farming.
3. Representative Concentration Pathways (RCPs)
RCPs are scenarios that describe future levels of greenhouse gases in the atmosphere. The study used RCP 4.5 (moderate emissions) and RCP 8.5 (high emissions) to explore two possible futures. For example, RCP 8.5 predicts severe warming, leading to a 4°C temperature rise in Tunisia by 2100. These pathways helped researchers estimate how different levels of climate change would impact wheat yields.
4. Evapotranspiration (ETâ‚€)
Evapotranspiration is the total water lost from soil (evaporation) and plants (transpiration). The reference evapotranspiration (ETâ‚€) in the study was calculated using the Penman-Monteith equation (see term 16). This measurement is vital for planning irrigation, as it shows how much water crops need. In Tunisia, rising temperatures increased ETâ‚€, meaning farmers might need more water to grow wheat.
5. Yield Gap
The yield gap is the difference between the maximum possible crop yield (under ideal conditions) and the actual yield farmers achieve. In the study, climate change widened this gap by up to 55% under RCP 8.5 by 2100. This highlights how droughts or heat stress reduce wheat production, threatening food security.
6. Water Productivity
Water productivity measures how much crop yield is produced per unit of water used. The study found that water productivity improved in some scenarios due to higher COâ‚‚ levels (see term 11). However, water scarcity in Tunisia could still limit gains. For example, less rainfall meant farmers needed more irrigation to maintain yields.
7. Rainfed Agriculture
Rainfed agriculture relies on rainfall rather than irrigation. In Tunisia, 60% of wheat is rainfed, making it vulnerable to droughts. The study warned that reduced rainfall and hotter temperatures could shrink harvests, forcing farmers to adopt irrigation or new crop varieties.
8. Durum Wheat
Durum wheat is a hardy crop used to make pasta and couscous. It’s crucial for Tunisia’s economy, providing 70% of the country’s wheat. However, the study showed that rising temperatures could shorten its growing season, reducing yields by up to 7% per 1°C increase.
9. Climate Change Adaptation
Adaptation refers to strategies to reduce the harm caused by climate change. The study tested delaying sowing dates (see term 10) to avoid heat stress during critical growth phases. Other strategies include drought-resistant crops or better irrigation.
10. Sowing Date
Sowing date is when farmers plant seeds. The study found that delaying sowing from mid-September to mid-December by 2100 could help Tunisian wheat avoid extreme heat. However, even with this adjustment, yields still dropped due to water shortages.
11. COâ‚‚ Fertilization Effect
Higher COâ‚‚ levels can boost plant growth by improving photosynthesis. In the study, this effect partially offset yield losses under RCP 4.5. For example, wheat yields increased by 20% by 2050 due to COâ‚‚, but this benefit faded under extreme warming (RCP 8.5).
12. Bias Correction
Bias correction adjusts climate model data to match real-world observations. The study used this method to fix errors in Med-CORDEX rainfall predictions. For example, raw model data overestimated rainfall, so researchers scaled it down to reflect actual Tunisian weather.
13. Phenology
Phenology is the timing of plant growth stages, like flowering or ripening. Warmer temperatures sped up wheat phenology in the study, shortening the growing season by 5 days per decade. This left less time for grains to develop, lowering yields.
14. Canopy Cover
Canopy cover measures how much of the soil is shaded by plant leaves. AquaCrop uses this to estimate photosynthesis and water use. In Tunisia, drought reduced canopy cover, limiting the plant’s ability to produce grains.
15. Soil Water Content
Soil water content is the amount of moisture in the soil. The study measured this to predict irrigation needs. For example, clay soils in Tunisia held more water, but declining rainfall still caused shortages during critical growth phases.
16. Penman-Monteith Equation
This formula calculates reference evapotranspiration (ETâ‚€). It uses weather data like temperature, humidity, and wind speed. In the study, ETâ‚€ helped estimate how much water wheat needed. The equation is:
ET₀ = [0.408Δ(Rₙ−G) + γ(900/(T+273))u(es−ea)] / [Δ + γ(1+0.34u)]
where Δ = slope of vapor pressure curve, Rₙ = solar radiation, G = soil heat flux, T = temperature, u = wind speed, es = saturation vapor pressure, and ea = actual vapor pressure.
17. Crop Cycle Duration
Crop cycle duration is the time from planting to harvest. In Tunisia, higher temperatures shortened the wheat cycle by 27 days by 2100 under RCP 8.5. This reduced grain-filling periods, leading to smaller harvests.
18. Water Use Efficiency
Water use efficiency measures how well crops convert water into yield. The study found efficiency improved under higher COâ‚‚ levels but warned that water shortages could negate these gains in arid regions like Tunisia.
19. Heat Stress
Heat stress occurs when temperatures harm plant growth. The study showed that temperatures above 26°C during flowering reduced wheat fertility and grain size. By 2100, heat stress could cut yields by 18% under RCP 8.5.
20. Drought Events
Droughts are periods of unusually low rainfall. In Tunisia, severe droughts already cut wheat yields by 50%. The study predicted droughts would become 3x more frequent by 2100, forcing farmers to rely on irrigation.
21. Statistical Metrics (RMSE, KGE)
RMSE (Root Mean Square Error) measures the average error between predictions and observations. For example, the study used RMSE = 3.25°C to show temperature prediction errors. KGE (Kling-Gupta Efficiency) evaluates how well models match real data. A KGE close to 1 (perfect score) meant Med-CORDEX reliably predicted Tunisian rainfall patterns.
22. Irrigation Requirements
Irrigation requirements are the extra water needed beyond rainfall. The study found Tunisia’s wheat would need up to 736 mm of irrigation by 2100 under RCP 8.5, compared to 223 mm historically. This raises costs for farmers.
23. Climate Projections
Climate projections are forecasts of future weather patterns. Using Med-CORDEX, the study predicted Tunisia’s rainfall would drop 37% by 2100, while temperatures would rise 4°C. These projections guided adaptation strategies like shifting sowing dates.
24. Sustainable Agriculture
Sustainable agriculture balances food production with environmental health. The study urged Tunisia to adopt practices like drought-resistant crops or efficient irrigation to protect wheat farming from climate change.
25. Food Security
Food security means reliable access to affordable, nutritious food. Tunisia already imports wheat, and the study warned that climate-driven yield gaps could worsen shortages. Adapting farming practices is critical to avoid hunger.
Reference:
Ghazouani, H., Jabnoun, R., Harzallah, A., Ibrahimi, K., Amami, R., Boughattas, I., … & Sher, F. (2025). Projected long-term climate change impacts on rainfed durum wheat production and sustainable adaptation strategies. Journal of Cleaner Production, 144980.
