Aboubakar Mohamadou, Charles Alain Bita
Department of Monetary and Banking Economics, University of Ngaoundere, Ngaoundere, Cameroon.
DOI: 10.4236/me.2025.1610077   PDF    HTML   XML   62 Downloads   366 Views   Citations

Abstract

The aim of this study is to analyse the effects of environmental vulnerability on food availability in sub-Saharan Africa. This work uses cross-country data covering the period 2000-2024. Following the empirical models developed by Turner et al. (2003) and Wilbanks (2007), and the fixed effects and random effects method, this study concludes that environmental vulnerability has significant negative effects on food availability. In view of this negative impact, it is imperative to invest heavily in policies for climate change adaptation and sustainable natural resource management. This includes promoting climate-resilient agricultural practices, developing early warning systems for extreme weather events, and investing in efficient irrigation and watershed management.

Keywords

Environmental Vulnerability, Food Availability, Food Security, Sub-Saharan Africa

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1. Introduction

More than four decades after Sen seminal work (Sen, 1981), the relationship between environmental vulnerability and food security in sub-Saharan Africa (SSA) remains a major issue. Sen showed that famines are not only caused by food shortages, but often by a lack of access due to the absence of “titles” or rights. This approach shifted the debate from a strictly productivist perspective to an analysis that integrates economic, social and institutional dimensions. Today, environmental factors (climate hazards, soil degradation, water scarcity) are considered key determinants of food insecurity, particularly in agricultural economies.

Climate variability, the intensification of natural disasters and the degradation of resources weigh heavily on food systems in SSA (FAO, 2024). Climate change exacerbates this pressure by reducing agricultural yields and undermining the livelihoods of rural communities (Solidarités International, 2020). Prolonged droughts and repeated floods are compromising food security in the long term, as shown by Ceesay et al. (2022) and Aroyehun (2023).

Food availability, the first pillar of food security, refers to the amount of food accessible through production, stocks or imports (FAO, 2012). However, agricultural production in SSA remains very low and vulnerable to climate shocks (Misselhorn & Schipper, 2012). In 2020, cereal yields reached only 1.7 tonnes/ha, compared to 4.1 in South Asia and 6.7 in the OECD (FAOSTAT, 2022). This dependence on rainfall, with only 7% of land irrigated, exacerbates the risks. Research by Lobell et al. (2011) has shown that droughts and heat waves are already reducing maize, wheat and rice production in many regions.

Undernourishment is on the rise: in 2022, 282 million people were affected, or 25% of the population, a figure that is likely to reach 310 million by 2030 (FAO, 2023). Added to this is a heavy dependence on imports, with an annual bill exceeding USD 40 billion (AfDB, 2021), making the region vulnerable to global price shocks. Finally, production variability is increasing, with a coefficient of variation twice that of stable regions (IPCC, 2021), and each 0.5˚C increase in average temperature reduces GDP growth per capita by 0.8 percentage points (IMF, 2020).

These findings highlight the urgent need to understand the interactions between environmental vulnerability and food availability. The inability of the SaH region to feed its population, despite its agricultural potential, warrants further research and climate resilience policies.

2. Food Availability: State of the Art

This section focuses on a review of the state of the art on food availability. The aim is to present the theoretical foundations and empirical research that frame our issue. This approach allows us to situate our study in the scientific context and identify the main debates and gaps in the existing literature.

2.1. State of the Art: Theoretical

The theoretical analysis of food availability has undergone a major shift, moving from an approach focused on agricultural production to a multidimensional view. Neoclassical theory, as illustrated by Schultz (1964), considers that food availability depends on the optimisation of production factors. Farmers, viewed as rational agents, maximise yields through the efficient use of land, labour and capital. The Green Revolution of the 1960s and 1970s seemed to validate this approach: high-yield seeds, fertilisers and irrigation led to a sharp increase in cereal production in several developing countries. Agricultural policies then focused on the dissemination of technologies and input subsidies.

However, the failure of this revolution to eradicate hunger, particularly in sub-Saharan Africa, revealed the limitations of this purely productivist vision. Sen (1981) then proposed his theory of capabilities, distinguishing between physical availability and effective access to food. For him, food security is based on the “entitlements” that enable individuals to obtain food. Thus, famine can result from a collapse in income or inflation, even if markets remain well supplied. This perspective broadened the analysis to include socio-economic factors such as poverty, inequality and market failures.

More recently, the environmental dimension has emerged as essential. Climate change, described by the IPCC as a “threat multiplier”, weakens agricultural systems through droughts, floods and soil loss. At the same time, infrastructure and logistics chains are recognised as crucial: post-harvest losses greatly reduce the amount of food available. Finally, the institutionalist approach (North, 1990) emphasises the role of laws, land policies and social norms that condition incentives to produce. Food availability therefore appears to be a complex phenomenon, influenced by production, access, environmental conditions and institutions.

2.2. State of the Empirical Art

The state of the empirical art on food availability in sub-Saharan Africa (SSA) highlights the multiplicity of determinants and causal mechanisms. Early research focused on agricultural factors, confirming their central role. Muriu & Tadesse, (2020) showed that investments in small-scale irrigation in Ethiopia increased maize yields by 35%, strengthening food availability even during periods of drought. These results confirm that improving production techniques and agricultural resilience is a key lever.

At the same time, empirical data validate Sen’s capabilities theory by highlighting the importance of economic access to food. CGIAR studies have shown that the poorest households are the most affected by food price volatility. Adedeji (2021), using consumption data from Nigeria, found that price increases, often linked to supply shocks, significantly reduce consumption among vulnerable households, leading to increased food insecurity even when markets are well supplied.

Recent empirical research has also focused on the impact of environmental vulnerability. Van der Wiel (2022) used high-resolution climate data to demonstrate the direct effect of heat waves and irregular rainfall on cereal production. These shocks lead to significant yield declines and increase the risk of large-scale food shortages.

Another key area is losses along the supply chain. The FAO (2021) has estimated that nearly 25% of total production is lost after harvest due to a lack of storage infrastructure, inadequate roads and the absence of a cold chain. Alimi et al. (2022) have shown that improving road infrastructure reduces these losses and increases the effective supply of food, particularly in urban areas.

Finally, recent research emphasises the role of institutions. Souley and Bita (2024), using the generalised method of moments, demonstrated that strong institutions and regional economic integration promote food availability and strengthen resilience to shocks.

Thus, the empirical literature converges towards a systemic understanding of food availability, linking production, access, environment, logistics and governance. This sets the stage for analysing the channels through which environmental vulnerability affects food security in WSA.

3. Empirical Framework of the Study

This section presents the methodological framework that guided our study on food availability in Sub-Saharan Africa. We describe in detail the variables used in our analysis, specifying their definitions and measurements. Next, we identify the data sources used, ensuring the reliability and relevance of our information base. Finally, we will outline the econometric estimation technique.

3.1. Methodology

3.1.1. Presentation of the Econometric Model Used and Justification for the Choice of Variables

The model we have chosen to study the relationship between environmental vulnerability and food availability is based on the fundamental work of researchers in socio-ecological systems, notably Turner et al. (2003) and Wilbanks (2007), who emphasise the multidimensional nature of vulnerability. These authors demonstrate that environmental vulnerability, as a combination of exposure, sensitivity and adaptive capacity, directly impacts the ability of agricultural systems to ensure sufficient food availability.

The functional form of the model may vary depending on the nature of the assumed relationship between environmental vulnerability and food availability in sub-Saharan Africa. A first simple linear specification consists of estimating the direct effect of environmental vulnerability on food availability (calculated as the sum of local agricultural production, imports and food aid, minus food exports). This relationship allows us to test the main hypothesis of a negative effect of environmental vulnerability on national food supply.

Equation (1): Functional form of the model

${\text{LogFA}}_{it}={\beta }_0+{\beta }_1{\text{EV}}_{it}+{\epsilon }_{it}$

A more elaborate specification of the model includes moderating and control variables that may influence or mitigate this effect. First, country structural characteristics, such as cereal yield (CY), measure agricultural productivity and its ability to offset the effects of environmental stress.

Secondly, social variables such as rural population (RP) and agricultural employment (AE) are included in order to capture demographic pressure and the structure of the rural labour market, which are likely to modulate the relationship between vulnerability and food availability.

Thirdly, economic variables such as food imports (FI) and food exports (FE) will be used to measure the effects of trade on the food balance. These variables make it possible to identify whether a country compensates for low production with imports or, on the contrary, suffers a loss of food through exports.

Fourthly, access to arable land (AL), an indicator of available natural resources, plays an essential role in the capacity to produce locally, especially in the context of climate variability.

Fifthly, specific interactions will be tested, for example between environmental vulnerability (EV) and variables such as arable land (AL), freshwater withdrawal for agriculture (FWA), fertiliser use (FU), and access to electricity (EAC), in order to analyse whether efficient agriculture can mitigate the negative effects of vulnerability. These interactive variables provide a more nuanced framework for understanding the conditions under which vulnerability affects food availability to a greater or lesser extent. Such interactions will also make it possible to identify the countries or periods where the effects are most pronounced.

The main explanatory variable in the model remains environmental vulnerability, measured by the ND-GAIN EV index, while the dependent variable is food availability, according to the methodology of Yusuf and Mutia (2024). The model takes into account the specificities of sub-Saharan Africa, where climate hazards, structural fragilities and food dependency are interdependent.

Thus, this dual specification (direct effect and interactions) aims to test the hypothesis of a negative effect of environmental vulnerability on food availability, while exploring possible mitigation mechanisms through economic, social, and agricultural variables.

Equation (2): Direct relationship

$\begin{array}{c}{\text{LogFA}}_{it}={\beta }_0+{\beta }_1{\text{EV}}_{it-1}+{\beta }_2{\text{CY}}_{it}+{\beta }_3{\text{RP}}_{ij}+{\beta }_4{\text{FWA}}_{ij}\\ +{\beta }_5{\text{FI}}_{ij}+{\beta }_6{\text{FE}}_{ij}+{\beta }_7{\text{LogAL}}_{it}+{\epsilon }_{it}\end{array}$

This specification focuses on the direct impact of environmental vulnerability on food availability while controlling for other relevant factors. The coefficient β₁ represents the direct effect of environmental vulnerability on food availability.

Equation (3): Indirect relationship

$\begin{array}{c}{\text{LogFA}}_{it}={\beta }_0+{\beta }_1{\text{EV}}_{it}+{\beta }_2{\text{CY}}_{it}+{\beta }_3{\text{RP}}_{ij}+{\beta }_4{\text{FWA}}_{ij}+{\beta }_5{\text{FI}}_{ij}+{\beta }_6{\text{FE}}_{ij}\\ +{\beta }_7{\text{LogAL}}_{it}+{\beta }_8{\left(\text{EV}\ast \text{AL}\right)}_{ij}+{\beta }_9{\left(\text{EV}\ast \text{FWA}\right)}_{ij}+{\beta }_{10}{\left(\text{EV}\ast \text{FU}\right)}_{ij}\\ +{\beta }_{11}{\left(\text{EV}\ast \text{EAC}\right)}_{it}+{\epsilon }_{it}\end{array}$

In addition to the direct relationship between environmental vulnerability (EV) and food availability (FA), an indirect specification of the model is proposed to examine moderating or mediating effects through interaction terms. This approach aims to better understand the channels through which environmental vulnerability influences food availability, taking into account the economic, agricultural and social environment of sub-Saharan African countries.

With this in mind, the model incorporates cross-interactions between environmental vulnerability and certain variables such as FWA, FU and EAC. This expanded specification allows for the formulation of differentiated recommendations, showing that strengthening agricultural productivity, improving access to international food markets, or balanced export management can modulate the impact of vulnerability on national food supply. This approach makes the model more operational and relevant for guiding public policy.

3.1.2. Description of the Variables Used

Food availability refers to the total amount of food available, including local production, imports and aid, minus exports. It therefore depends on trade. This approach, used by Tadesse & Alimi (2020), reveals the importance of imports in ensuring regional food stability and security.

Between 2000 and 2024, food availability in sub-Saharan Africa rose from 2278 to 2478 kcal/person/day, an increase of 200 kcal. This increase reflects efforts in production, imports and food aid, despite temporary shocks. However, the optimal threshold of 2500 kcal has yet to be reached (Figure 1).

Figure 1. Evolution of food availability in SSA. Source: Authors.

• The variable of interest: environmental vulnerability

Environmental vulnerability refers to a system’s limited capacity to cope with climate shocks. According to Wilbanks (2007), it depends on both external threats and internal characteristics. Smith & Jones (2021) show, using the ND-GAIN index, that high vulnerability increases food instability, justifying targeted adaptation policies.

Figure 2. Evolution of environmental vulnerability in SSA. Source: Authors.

Between 2000 and 2024, the EV index of food vulnerability in sub-Saharan Africa fell from 0.679 to 0.338, reflecting improved resilience. This decline is the result of agricultural efforts and risk management policies. However, stagnation between 2006 and 2011 and persistent challenges (poverty, conflict, climate) are still hampering the reduction of vulnerability. (Figure 2)

• Simultaneous evolution of the dependent variable and the variable of interest

The analysis shows an inverse correlation between food availability and vulnerability in sub-Saharan Africa: the increase from 2278 to 2478 kcal/person/day is accompanied by a modest decrease in EV (0.463 to 0.432). This partial improvement highlights the fact that increasing food supply must be complemented by targeted social and structural policies. (Figure 3)

Figure 3. Evolution of environmental vulnerability and FA in SSA. Source: Authors.

• Control variables:

• Cereal yield:

Measured in kilograms per hectare of harvested land, includes wheat, rice, maize, barley, oats, rye, millet, sorghum, buckwheat and mixed cereals. Cereal production data refer only to crops harvested for dry grain. Cereal crops harvested for hay, or harvested green for human or animal consumption or silage, as well as those used for grazing, are excluded. The FAO attributes production data to the calendar year in which most of the harvest took place. Most crops harvested at the end of the year will be used the following year.

• Rural population:

Refers to people living in rural areas, as defined by national statistical offices. It is calculated as the difference between the total population and the urban population.

• Freshwater abstraction for agriculture

Freshwater withdrawal for agriculture corresponds to the share of water extracted from natural sources for irrigation, livestock farming and agricultural activities. Measured as a percentage of total withdrawals (World Bank), it indicates the pressure of the agricultural sector on water resources and is a key indicator of sustainability and food security.

• Agricultural employment:

Agricultural employment refers to the share of the working population employed in crop production, livestock farming, fishing, hunting and forestry. Measured as a percentage of total employment (World Bank, SL.AGR.EMPL.ZS), it assesses a country’s dependence on agriculture and serves as a key indicator in studies on food security, rural poverty and economic transitions.

• Food imports:

This indicator measures the share of food products in a country’s total merchandise imports, expressed as a percentage. It reflects a country’s level of dependence on foreign countries for its food supply. Merchandise imports include all traded goods whose economic ownership is transferred between a resident and a non-resident, with the exception of certain specific categories such as merchanting, non-monetary gold and certain components of services (travel, construction, government...).

• Food exports:

Represent the share of food products that a country sells abroad, generally measured in value or as a percentage of total merchandise exports. This variable makes it possible to assess a country’s integration into international food markets and its role in global food security. It is frequently used in economic studies to analyse the impact of trade on growth, agricultural income and food availability. For example, Hossain and Kim (2022) examined the effect of food exports on economic growth and food security in developing countries, using this variable as a key explanatory variable.

• Arable land:

This indicator measures the proportion of arable land in a country’s total land area, expressed as a percentage. Arable land refers to land temporarily cultivated for the production of crops for harvest (grains, vegetables, roots...), including land temporarily fallow (less than five years).

Not included in this category are: permanently cultivated land (fruit plantations, vineyards, coffee plantations...), permanent grassland, forests, and unproductive land (deserts, urban areas...). The indicator provides an overview of a country’s agricultural potential and its capacity to produce food or cash crops.

• Simultaneous evolution of the dependent variable and all control variables

The evolution of food availability (FA) in sub-Saharan Africa between 2000 and 2024 shows steady progress, supported by both a moderate improvement in cereal yields (CY) and a significant contribution from food imports (FI). This increase is accompanied by a slight decrease in environmental vulnerability (EV), suggesting that agroecological conditions are gradually becoming more favourable to food security (Figure 4).

However, the continued decline in the rural population (RP) and agricultural employment (AE) reflects a structural transition in the agricultural sector, which could weaken the productive base in the long term. Furthermore, the increase in food exports (FE) in certain periods has not slowed the rise in FA, probably due to higher imports. The stability of the proportion of arable land (LogAL) indicates little change in cultivated areas, suggesting that gains in FA are mainly due to agricultural intensification. Thus, the improvement in FA is based on a fragile balance between agricultural performance, trade openness and environmental resilience.

Figure 4. Evolution of the dependent variable and all control variables. Source: Authors.

3.2. Data Sources, and Estimation Technique

3.2.1. Data Sources

The data used in the model estimation come from various secondary sources. The data used in the study are panel data covering a total of 40 countries over the period 2000-2024, selected on the basis of data availability. All data used in this study come from the World Development Indicators (WDI), the FAOSTAT database and the ND-GAIN database. The sample covers countries in sub-Saharan Africa. The inclusion of these 40 countries in the same sample can be justified by their strong historical and cultural roots, in addition to their economic ties as part of economic integration zones.

Table 1 below presents the different indicators used to measure the explanatory and dependent variables based on existing theories.

Table 1. Measurements of variables and parameters to be estimated.

Variables	Measures	Parameters
FOOD AVAILABILITY (FA)	Calculated as follows: local agricultural production + imports and food aid – food exports.	//
ENVIRONMENTAL VULNERABILITY (EV)	Measured by the environmental vulnerability index calculated in the ND-GAIN database.	${\beta }_1$
CEREAL YIELD (CY)	Measured in kilograms per hectare of harvested land. Cereal production data only includes crops intended for dry grain production.	${\beta }_2$
RURAL POPULATION (RP)	This is calculated as the difference between the total population and the urban population.	${\beta }_3$
FRESHWATER WITHDRAWAL FOR AGRICULTURE (FWA)	measured as a percentage of total freshwater withdrawals (% of total freshwater withdrawals), as defined by the World Bank.	${\beta }_4$
FOOD IMPORTS (FI)	Measures the share of food products in a country’s total merchandise imports, expressed as a percentage.	${\beta }_5$
FOOD EXPORTS (FE)	Measures the share of food products in a country’s total merchandise exports, expressed as a percentage.	${\beta }_6$
ARABLE LAND (AL)	Measures the proportion of arable land in a country’s total land area, expressed as a percentage.	${\beta }_7$

Source: authors.

3.2.2. Estimation Technique

The analysis of the effects of environmental vulnerability on food availability frequently uses panel data, combining temporal and spatial observations. Fixed effects and random effects methods are essential econometric tools for processing this data. Hausman (1978) and Mundlak (1978) established the theoretical basis for managing unobservable heterogeneity between statistical units, thereby reducing biases related to country- or region-specific characteristics that can influence both vulnerability and food availability.

The fixed effects method explicitly controls for these unobserved factors by focusing on intra-group variation, which is useful when factors specific to each unit, such as local agricultural policies or climatic conditions, may bias the results. In contrast, the random effects method, proposed by Swamy (1970) and Amemiya (1971), treats these specific effects as random variables, increasing the efficiency of estimates when the independence between these effects and the explanatory variables is verified.

4. Presentation and Discussion of Study Results

This section is the core of our analysis, where we present and discuss the results of our econometric investigation. This will provide a comprehensive understanding of the dynamics of food availability in Sub-Saharan Africa.

4.1. Descriptive Statistics and Correlation Matrix

Table 2 provides an initial overview of our data, allowing us to better understand the characteristics of each variable. Food availability (LogFA), with an average of 5.819 and a standard deviation of 1.119 over 1000 observations, shows some variability, ranging from 1.998 to 7.500. We also note significant differences for variables such as cereal yield (CY) and food exports (FE), highlighting the diversity of situations in sub-Saharan Africa. These figures provide us with a solid basis for analysing their relationships. We will now proceed to execute the correlation matrix in order to explore the linear relationships between these variables.

Table 2. Descriptive statistics of the variables.

Variables	Obs	Means	Standard deviation	Min	Max
LogFA	1000	5.819	1.119	1.998	7.500
EV	1000	0.502	0.0623	0.338	0.6798
CY	1000	1500.786	1171.382	0.1	9453.7
RP	1000	59.377	16.800	8.693	91.754
FWA	1000	57.742	27.569	0.558	98.179
FI	1000	19.311	9.794	0.474	62.416
FE	1000	33.005	29.402	0.0157	100
LogAL	1000	0.989	0.528	0.493	1.718

Source: Authors.

Here we present the correlation matrix of our variables, highlighting the linear relationships between them (at the 5% threshold) (Table 3). We observe various significant correlations, such as that between Food Availability (LogFA) and Rural Population (RP) (0.367*), or the impact of Environmental Vulnerability (EV) on other factors. These initial observations provide us with valuable insights into the potential links that we will explore further. We will now proceed to perform stationarity tests, a crucial step in validating our model.

Table 3. Correlation matrix between variables (significance threshold = 5%).

	LogFA	EV	CY	RP	FWA	FI	FE	LogAL
LogFA	1
EV	0.122*	1
CY	−0.116*	0.066*	1
RP	0.367*	0.378*	−0.049	1
FWA	0.325*	0.244*	0.161*	0.352*	1
FI	−0.333*	0.216*	−0.114*	−0.048	−0.063*	1
FE	−0.229*	0.343*	0.091*	0.218*	0.227*	0.461	1
LogAL	0.210*	0.282*	0.249*	0.481*	0.102*	0.188*	0.384*	1

Source: Authors.

Table 4. Analysis of the stationarity test for the model variables.

	LEVEL TEST		DIFFERENCE TEST 01		DIFFERENCE TEST 02		INTEGRATION ORDER
	I-P-S stat	I-P-S prob	I-P-S stat	I-P-S Prob	I-P-S stat	I-P-S prob
LogFA	−8.348	0.000					I (0)
EV	−5.718	0.000					I (0)
CY	−9.609	0.000					I (0)
RP	−2.688	0.003					I (0)
FI	−5.2240	0.000					I (0)
FE	−7.279	0.000					I (0)

Source: Authors.

Table 4 presents the results of our stationarity tests for the model variables. We used the IPS (Im, Pesaran, Shin) test. The probability values (I-P-S prob) for all our variables (LogFA, EV, CY, RV, FI, FE) are below 0.05 (and even 0.01) in level. This indicates that all our variables are stationary at order I(0). This fully justifies our choice of the fixed-effect and random-effect estimation technique, which is suitable for stationary panel data, thus ensuring the validity and robustness of the estimates.

4.2. Presentation, Interpretation and Discussion of the Results

This section is dedicated to presenting the econometric results obtained from our model.

The Food Availability (FA) variable is log-transformed (Log(FA)) to allow the coefficients of the level explanatory variables (such as EV, CY, FI, AL) to be interpreted as semi-elasticities (β × 100). This indicates the percentage effect on the FA resulting from a one-unit change in the explanatory variable. Additionally, it helps to normalise the distribution and reduce the heteroscedasticity of a variable that is often highly skewed and unbounded below.

Using a log-level model in this work (log-transformed dependent variable, level independent variables) is particularly useful because the main concern is expressing the marginal effects in terms of a growth rate or percentage variation, which is more relevant for economic magnitudes such as food availability. Furthermore, this provides results that are easily interpretable in terms of the proportional impact (percentage) of environmental vulnerability on food supply, even though the EV variable is itself an index.

Table 5 provides the estimated coefficients for each explanatory variable, along with their corresponding Student’s t-statistics (in parentheses) and their level of significance. To determine which of these two models, fixed effects or random effects, is most appropriate for our analysis, we will perform the Hausman test. This test will allow us to choose the most efficient and robust specification.

Table 5. Model estimation results.

	(Fixed effect)	(Random effect)
	LogFA	LogFA
EV	−1.604**	−1.703***
	(−3.21)	(−3.43)
CY	0.0000987***	0.0000955***
	(8.49)	(8.10)
RP	−0.000733	−0.00116
	(−0.44)	(−0.70)
FWA	0.00148	0.00219
	(1.16)	(1.75)
FI	0.00591***	0.00560***
	(5.39)	(5.03)
FE	−0.00291***	−0.00300***
	(−5.86)	(−5.97)
LogAL	1.319***	1.217***
	(13.51)	(13.28)
Con	5.112***	5.258***
	(18.28)	(17.37)
Chi2	//	486.995
p-value	//	0.0000
Fisher	73.54	//
p-value	0.0000	//
Pseudo R2	0.3510	0.3502

Source: authors. Note: The figures in brackets represent Student’s statistics. * (p ≤ 0.1); ** (p ≤ 0.05); *** (p ≤ 0.01) represent significance at the 10%, 5% and 1% thresholds.

Table 6. Hausman test and choice of optimal model.

	(Fixed effect)	(Random effect)	Hausman
	LogFA	LogFA	(b) - (a)
EV	−1.604**	−1.703***	0.0990665
	(−3.21)	(−3.43)
CY	0.0000987***	0.0000955***	3.21e−06
	(8.49)	(8.10)
RP	−0.000733	−0.00116	0.0004281
	(−0.44)	(−0.70)
FWA	0.00148	0.00219	−0.0007177
	(1.16)	(1.75)
FI	0.00591***	0.00560***	0.0003098
	(5.39)	(5.03)
FE	−0.00291***	−0.00300***	0.0000869
	(−5.86)	(−5.97)
LogAL	1.319***	1.217***	0.101994
	(13.51)	(13.28)
Cons	5.112***	5.258***	//
	(18.28)	(17.37)
Hausman probability	//	//	0.0028
Chi2	//	486.995	//
p-value	//	0.0000	//
Fisher	73.54	//	//
p-value	0.0000	//	//
Pseudo R2	0.3510	0.3502	//
Wald test	//	487.00	//
Observations	999	999	//

Source: authors. Note: The figures in brackets represent Students’ statistics. * (p ≤ 0.1); ** (p ≤ 0.05); *** (p ≤ 0.01) represent significance at the 10%, 5% and 1% thresholds.

The result of the Hausman test indicates a zero probability (Prob > chi² = 0.0000), which leads to the rejection of the null hypothesis that the differences between fixed-effects and random-effects estimators are not systematic. In other words, country-specific effects are correlated with the explanatory variables in the model. Consequently, the fixed-effects model is the most appropriate for this analysis. This ensures unbiased and more reliable estimates in the study of food availability. (Table 6)

• Econometric and economic interpretations of variable coefficients

In this subsection, we delve into the analysis of the estimated coefficients of our model. We will interpret their econometric meanings and concrete economic implications.

• Environmental vulnerability (EV)

The estimated coefficient for environmental vulnerability (EV) is −1.604, statistically significant at the 5% threshold (p < 0.05). This result indicates that a one-unit increase in EV to an approximately 160.4% decrease in food availability (FA), all other things being equal. This significant reduction highlights the critical impact of environmental factors on a country’s ability to ensure adequate food security.

Economically, this relationship is consistent with the realities observed in vulnerable regions. Increased environmental vulnerability, often amplified by climate change (droughts, floods, soil degradation) directly affects agricultural productivity and disrupts supply chains, reducing local production and limiting access to food. This phenomenon is fully consistent with food security theory, which identifies environmental challenges as major threats to the stability and resilience of food systems.

The negative sign and significance of the EV confirm the findings of existing literature on the deleterious impacts of environmental degradation. The work of Lima et al. (2024), who developed an environmental vulnerability index, already implicitly recognises this link. Our study provides robust empirical confirmation and accurate quantification of the effect of EV on FA in sub-Saharan Africa, offering strong evidence to support the integration of environmental considerations into food security policies and highlighting the urgency of strengthening resilience to climate hazards.

• Cereal yield (CY)

The coefficient for cereal yield (CY) is estimated at 0.0000987, which is highly significant at the 1% threshold (p < 0.01). Although the absolute value is low, the high significance indicates that a one kilogram per hectare increase in cereal yield leads to an increase of approximately 0.00987% in FA, all other things being equal. This result demonstrates a positive and robust relationship, even if its direct unit impact is modest.

From an economic perspective, this finding is fundamental. Cereals are the staple of the global diet, and improving their yields directly increases food supply. Higher yields allow more to be produced on the same area of land, thereby contributing to food availability. These results are in line with the theory of agricultural production and food security, where sustainable intensification is seen as a major lever for ensuring sufficient supply.

Previous research, such as that by El Yacoubi et al. (2021), highlights the importance of cereal yields for food security. Our study provides a precise quantification of this effect in the context of sub-Saharan Africa, reinforcing the need to invest in improved seeds, efficient irrigation techniques and farmer training to sustainably boost productivity.

• Rural population (RP)

The coefficient for rural population (RP) is −0.000733, but it is not statistically significant (p > 0.1). Thus, even though a one-unit increase in the rural population is associated with an approximate 0.0000733% decrease in FA, no firm conclusions can be drawn about its direct impact.

The relationship between rural population and FA is complex. On the one hand, a larger rural population could increase the agricultural labour force and stimulate production. On the other hand, rapid population growth without parallel improvements in infrastructure or productivity can put pressure on land and water, potentially reducing per capita FA. The lack of significance suggests that these contradictory effects may offset each other or that other socio-economic factors play a more decisive role.

The literature reflects this ambivalence. Some studies highlight demographic pressure on resources, while others emphasise the importance of rural populations for food production. The work of Flanagan et al. (2011) illustrates this complexity and highlights the need for in-depth analysis of rural dynamics to understand their real impact on food availability in sub-Saharan Africa.

• Freshwater withdrawal for agriculture (FWA)

The coefficient for freshwater abstraction for agriculture (FWA) is 0.00148, which is not significant (p > 0.1). This indicates that a one percentage point increase in agricultural withdrawals is associated with an increase of approximately 0.000148% in FA, but this result is not statistically reliable.

Economically, although increased withdrawals could theoretically stimulate agricultural production, the non-significance can be explained by low water use efficiency. Higher volumes do not guarantee proportional gains in production due to losses, inefficient techniques or inadequate infrastructure. Furthermore, excessive withdrawals can compromise the sustainability of water resources.

The literature highlights the complexity of the water-agriculture relationship. Han (2025) emphasises the importance of technology and efficient management in addressing water scarcity. Our findings suggest that quantity alone is not sufficient; more efficient and sustainable use of water resources is essential to improve FA.

• Food imports (FI)

The food import coefficient (FI) is 0.00591, which is highly significant at the 1% threshold (p < 0.01). A one percentage point increase in the share of food imports leads to an increase of approximately 0.000591% in FA, all other things being equal.

Economically, this result reflects the crucial role of imports in supplementing domestic production, stabilising prices and diversifying supply. Imports help to fill production gaps and ensure sufficient supply, particularly in times of climatic or economic shocks.

Analyses such as those by Anautor (2025) confirm the importance of imports in stabilising food security. Our study provides a precise quantification of this effect, highlighting the importance of open trade policies and diversification of sources to strengthen food resilience.

• Food exports (FE)

The coefficient for food exports (FE) is −0.00291, which is highly significant at the 1% level (p < 0.01). A one percentage point increase in food exports reduces FA by approximately 0.000291%. Economically, this result reflects the dilemma between economic gains from exports and national food security. Exports generate foreign exchange, but a strong export orientation can reduce the availability of food for the local population. In countries with fragile food security, overly export-oriented production can exacerbate deficits.

The work of Hossain and Kim (2022) illustrates the complexity of the impact of exports on food security. Our study confirms that, in the context of sub-Saharan Africa, increasing food exports can adversely affect food availability, highlighting the need for a balance between foreign trade and food security.

• Arable land (LogAL)

The coefficient for arable land (LogAL) is 1.319, which is highly significant at the 1% threshold (p < 0.01). A 1% increase in the proportion of arable land leads to an increase of approximately 1.319% in FA. The elasticity greater than unity indicates that FA is more than proportionally sensitive to changes in the proportion of arable land.

Economically, arable land is an essential resource for food production. A larger proportion of arable land directly increases production capacity. The elasticity greater than 1 highlights the crucial importance of access to and use of such land in sub-Saharan Africa, where optimisation of the resource has a significant impact on food security.

Liu et al. (2010) confirm the importance of this land for agriculture. Our study reinforces this argument and provides solid empirical evidence of the effect of arable land on FA, supporting policies for sustainable management and investment in agricultural productivity.

• Constant (Cons)

The coefficient of the constant is 5.112, which is highly significant at the 1% level (p < 0.01). It represents the baseline level of FA when all other variables are zero, incorporating the effect of omitted factors that contribute to food availability. Economically, it reflects an inherent level of FA independent of the variables included in the model.

• Validation of results

The overall statistics confirm the robustness of the model. The Fisher value of 73.54 (p = 0.0000) indicates that the model is collectively significant. The Pseudo R² of 0.3510 means that 35.1% of the variance in FA is explained by the variables included. Finally, the high number of observations (999) confers great statistical robustness, reducing the risk that the results are due to chance.

• Post-estimation tests on the fixed-effect model

Since the probability of this test is below the 0.05 threshold, we reject the null hypothesis of homoscedasticity. This result indicates the presence of significant heteroscedasticity in the model errors, meaning that the variance of the errors is not constant (Table 7).

Table 7. Breusch-Pagan Lagrange Multiplier (LM) test.

Chi2	8292.51
Prob	0.000

Source: Authors.

Table 8 confirms the previous result. Since the probability is lower than the significance threshold of 0.05 (and even 0.01), this confirms the significant presence of heteroscedasticity in the errors of our model.

Table 8. Heteroscedasticity test.

Chi2	20879.27
Prob	0.000

Source: Authors.

Table 9 showing the results of the heteroscedasticity test, indicates a probability (Prob) of 0.000. This result, being well below the usual significance threshold of 0.05, leads us to reject the hypothesis of homoscedasticity. In this context, it seems imperative to perform sensitivity and robustness analyses and a heterogeneity test on our baseline results.

Table 9. Shapiro-Wilk normality test for residuals.

Variable	Obs	W	V	Z	Prob
Residues	999	0.84725	96.251	11.309	0.00000

Source: authors.

In order to correct the significant heteroscedasticity revealed by the Breusch-Pagan test, and to account for the intragroup autocorrelation of the residuals (i.e., the correlation of errors over time for the same country), we will re-estimate the model using Cluster-Robust Standard Errors (CRSE). By clustering these errors at the country level, this technique guarantees valid statistical inferences and reliable significance tests. This, in turn, allows for a more precise estimation of the real impact of Environmental Vulnerability on Food Availability.

The second column presents the Fixed Effects estimation with Cluster-Robust Standard Errors (CRSE) (Table 10), which has been corrected for both heteroscedasticity and intragroup autocorrelation. We observe that the coefficients for the explanatory variables remain virtually unchanged compared to the baseline result (first column), confirming the direction and magnitude of our effects. However, the standard errors in the second column are generally larger, reflecting a more cautious and reliable statistical inference.

Table 10. Cluster-Robust Standard Errors fixed effect estimation (CRSE).

	(Fixed effect)	(Fixed effect)
	Baseline Result	Cluster-Robust Standard Errors (CRSE)
EV	−1.604**	−1.60395***
	(−3.21)	(−4.32)
CY	0.0000987***	0.0000987***
	(8.49)	(10.54)
RP	−0.000733	−0.0007329*
	(−0.44)	(−1.70)
FWA	0.00148	0.0014769*
	(1.16)	(1.75)
FI	0.00591***	0.005911***
	(5.39)	(7.24)
FE	−0.00291***	−0.0029099***
	(−5.86)	(−10.85)
LogAL	1.319***	1.318933***
	(13.51)	(14.57)
Cons	5.112***	5.112335***
	(18.28)	(5.55)
Fisher	73.54	25.65
p-value	0.0000	0.0000
Pseudo R2	0.3510	0.3510
Observations	1000	1000

Source: authors.

It is essential to check whether this increase in the standard errors has reduced the statistical significance of the variables, particularly the negative effect of the VUE (Environmental Vulnerability). If the key variables maintain their level of significance, we conclude that the baseline results are robust to issues of residual errors. This re-estimation therefore strengthens the validity of the conclusions regarding the impact of Environmental Vulnerability.

5. Sensitivity Analysis, Robustness Analysis, and Heterogeneity Test of Basic Results

This section is devoted to assessing the reliability of our results. We will examine the sensitivity and robustness of our conclusions by varying the estimation methods and introducing new variables. In addition, we will perform heterogeneity tests to refine our understanding of the underlying dynamics.

Agricultural employment includes all persons involved in agricultural production, livestock farming, forestry and fishing, whether as their main or secondary activity. According to the FAO (2020), it is often the main source of income in rural areas, contributing to both sales and self-consumption.

It is important to include agricultural employment in a model for studying food security in sub-Saharan Africa. As the sector is a driver of production and the main provider of employment, its inclusion would make it possible to test the robustness of the results and analyse the impact of labour on food availability. This would help to assess the effects of employment policies on food stability in the region.

The potential endogeneity between Environmental Vulnerability (VE) and Food Availability (DA) is mitigated by including country and time fixed effects to control for time-invariant unobserved factors, and crucially, by using System GMM estimation. This method corrects for simultaneity and omitted variable bias through the instrumentation of potentially endogenous variables (including lagged DA) with their past values. This approach, essential for dynamic panel data, relies on the robust methodology developed by Blundell and Bond (1998).

The robustness analysis was conducted by comparing a fixed effects model with a model using the Generalised Method of Moments in System (GMM-syst), which incorporates agricultural employment (AE). This comparison aimed to verify the stability of the results (Table 11).

Table 11. Change in estimation technique (MMG-syst) and inclusion of new variable.

	(fixed effect)	(MMG-syst)
	LogFA	LogFA
LogFAt−1	//	0.8892124***
	//	(138.87)
EV	−1.604**	−1.444***
	(−3.21)	(−5.36)
CY	0.0000987***	0.0000298***
	(8.49)	(4.25)
RP	−0.000733	−0.00202**
	(−0.44)	(−2.65)
FWA	0.00148	//
	(1.16)	//
FI	0.00591***	0.00615***
	(5.39)	(8.30)
FE	−0.00291***	−0.00133***
	(−5.86)	(−8.90)
LogAL	1.319***	0.0637
	(13.51)	(1.95)
AE	//	0.00362***
	//	(4.49)
Cons	5.112***	1.135***
	(18.28)	(7.51)
Sargan		36.07464
p-value (Sargan)		0.8263
p-value AR(1)		0.0012
p-value AR(2)		0.6512
Observations		958
Instruments		24

Source: authors. Note: The figures in brackets represent Student’s statistics. * (p ≤ 0.1); ** (p ≤ 0.05); *** (p ≤ 0.01) represent significance at the 10%, 5% and 1% thresholds.

The main conclusions are robust: environmental vulnerability (EV) has a negative effect on food availability (FA), imports have a positive effect and exports have a negative effect. Although the rural population (RP) becomes significantly negative and the effect of arable land (LogAL) loses its significance, the directions of the effects of the key variables are maintained. These results confirm the reliability of the model. The next step is to analyse the transmission channels by introducing interaction variables between EV and other factors to understand how its effect is moderated.

EV*Arable Land (EV*AL): The interaction is negative and significant (−0.000242***), indicating that a larger proportion of arable land amplifies the negative impact of environmental vulnerability on food availability. This can be explained by a high dependence on extensive agriculture, making large farms more vulnerable to climate shocks. The result shows that the mere quantity of land does not guarantee resilience, and highlights the importance of sustainable management (Table 12).

EV*Water withdrawal (EV*FWA): The interaction coefficient is also negative and significant (−0.00482***). Increased freshwater withdrawals for agriculture, in a context of vulnerability, exacerbate the negative effect on food availability. Un r uncontrolled water use can lead to overexploitation of resources and make the agricultural system more fragile in the face of droughts, challenging the idea that more irrigation is always beneficial.

Table 12. Testing the transmission channels of the link between environmental vulnerability and food availability in SSA.

	(EV*FA)	(EV*FWA)	(EV*FU)	(EV*EAC)
	LogFA	LogFA	LogFA	LogFA
LogFAt−1	0.895***	0.886***	0.866***	0.898***
	(41.88)	(40.41)	(107.92)	(48.94)
EV	−0.851**	−0.927*	−1.145***	−0.891***
	(−2.89)	(−2.47)	(−3.39)	(−3.44)
CY	0.0000699***	0.0000388***	0.0000746***	0.0000514***
	(6.82)	(5.25)	(7.36)	(7.25)
RP	−0.00353***	−0.00198**	−0.000545	−0.00702***
	(−4.48)	(−2.61)	(−0.75)	(−9.14)
AE	0.00386***	0.00352***	0.00189**	−0.00170*
	(6.22)	(4.49)	(2.63)	(−2.06)
FI	0.00629***	0.00676***	0.00528***	0.00580***
	(10.03)	(10.66)	(8.45)	(8.50)
FE	−0.00133***	−0.00136***	−0.00141***	−0.00151***
	(−9.41)	(−8.59)	(−8.67)	(−8.25)
LogAL	0.275***	0.0514	0.0705*	0.159***
	(3.33)	(1.11)	(2.00)	(3.66)
EV*AL	−0.000242***
	(−7.59)
EV*FWA		−0.00482***
		(−4.62)
EV*FU			−0.00386***
			(−12.51)
EV*EAC				−0.0103***
				(−13.01)
Cons	0.829***	1.022***	1.101***	1.463***
	(4.83)	(8.82)	(6.14)	(11.11)
Sargan Chi2	35.711	36.036	34.407	36.403
Sargan p-value	0.8375	0.8275	0.8743	0.8159
AR(1) p-value	0.0017	0.0015	0.0015	0.0015
p-value AR(2)	0.5105	0.6355	0.5553	0.5541
Observations	958	958	958	958
Instruments	25	25	25	25

Source: author. Note: The figures in brackets represent Student’s statistics. * (p ≤ 0.1); ** (p ≤ 0.05); *** (p ≤ 0.01) represent significance at the 10%, 5% and 1% thresholds.

EV*Fertiliser use (EV*FU): This interaction is also negative and highly significant (−0.00386***). The use of fertilisers, often seen as a means of intensifying production, paradoxically makes the system more sensitive to the effects of environmental vulnerability. In a fragile environment, excessive use of chemical inputs can weaken ecosystems, suggesting that intensification must be carried out in a sustainable manner so as not to compromise long-term food security.

EV*Access to electricity (EV*EAC): The interaction is negative and significant (−0.0103***), which is surprising. The negative impact of environmental vulnerability is amplified when access to electricity is higher. This phenomenon could be due to unsustainable use of electricity, such as excessive groundwater pumping, which makes agriculture more vulnerable. This result emphasises the need to link rural electrification to sustainable resource management and climate adaptation policies.

To refine the analysis, the study tests for heterogeneity of effects based on country income levels (low, lower middle, upper middle), using the World Bank classification for fiscal year 2025. This step is crucial in determining whether the dynamics observed globally vary according to each country’s economic context and in identifying specificities that would be masked by an aggregate analysis.

Table 13. Heterogeneity by income level.

	(Low-income countries)	(Middle-income countries)	(Upper middle-income countries)
	LogFA	LogFA	LogFA
EV	−1.327***	−0.238	−2.346
	(−3.78)	(−0.29)	(−1.12)
CY	0.000230***	0.000449***	−0.0000177
	(16.98)	(13.42)	(−1.19)
RP	0.00430*	0.00664*	−0.0176***
	(2.35)	(2.47)	(−3.91)
AE	−0.00403***	0.00258	0.0153**
	(−4.77)	(1.45)	(2.68)
FI	0.00164*	0.00825***	0.000836
	(2.18)	(4.95)	(0.16)
FE	0.000534	−0.00556***	0.00897**
	(1.65)	(−7.32)	(2.76)
LogAL	0.967***	1.686***	0.463
	(11.18)	(10.89)	(1.78)
Cons	5.383***	3.134***	6.219***
	(19.32)	(7.65)	(7.22)
Fisher	161.24	77.26	4.07
p-value	0.0000	0.0000	0.0004
Pseudo R2	0.7378	0.5899	0.1505
Observations	425	399	175

Source: Authors. Note: The figures in brackets represent Students’ statistics. * (p ≤ 0.1); ** (p ≤ 0.05); *** (p ≤ 0.01) represent significance at the 10%, 5% and 1% thresholds.

For low-income countries, environmental vulnerability (EV) has a very significant negative impact on food availability (−1.327***). This is the result of their heavy dependence on rain-fed agriculture, fragile infrastructure and weak adaptive capacities (Table 13).

In middle-income countries, the effect of EV is not significant (−0.238). This could be explained by greater economic diversification and adaptive capacities that mitigate the direct impact of environmental shocks.

Counterintuitively, for upper-middle-income countries, the EV coefficient is negative and large (−2.346) but not significant. This may be due to the small sample size, general economic resilience, or unobserved factors that mask a direct effect. However, the negative sign suggests a trend.

6. Conclusion

This study conducted an in-depth analysis of the factors that determine food availability in sub-Saharan Africa, focusing on the effects of environmental vulnerability. The study followed a rigorous methodology, beginning with a review of the literature and a presentation of stylised facts, followed by a detailed description of the methodological framework, including the use of the system of generalised moments method for robustness. The results were discussed in depth and their robustness was confirmed through several tests.

The study identified concrete courses of action to strengthen food availability. A key recommendation is to promote sustainable agricultural practices. Policies should encourage innovations in water management and agroecological methods to reduce dependence on chemical inputs and improve crop resilience. The aim is to ensure that agriculture in the region can better withstand climate shocks.

Another key recommendation concerns rural electrification. It is important that electricity access projects are integrated with sustainable resource management initiatives. For example, electricity should be used for efficient irrigation systems, rather than allowing the overexploitation of water resources. By linking energy to sustainable development, a simple service can be transformed into a real lever for climate resilience.

Conflicts of Interest

The authors declare no conflicts of interest regarding the publication of this paper.

References

[1]	Adedeji, O. (2021). Impact of Food Price Volatility on Household Consumption in Nigeria. National Consumption Data. https://ideas.repec.org/a/eee/jfpoli/v102y2021ics0306919221000397.html
[2]	AfDB (African Development Bank) (2021). Report on Food Security in Sub-Saharan Africa. AfDB.
[3]	Alimi, T., Olayemi, A. O., & Adeyemi, O. O. (2022). Improving Food Supply through Infrastructure Development in Urban Africa. Journal of Food Security, 14, 45-62. [Google Scholar] [CrossRef]
[4]	Amemiya, T. (1971). The Estimation of the Variances in a Variance-Components Model. International Economic Review, 12, 1-13.
[5]	Anautor, A. (2025). Role of Food Imports in Stabilising Food Security. Journal of Global Food Policy, 18, 55-72.
[6]	Aroyehun, O. (2023). Climate Shocks and Food Security in Sub-Saharan Africa. Environmental Economics Review, 12, 78-95.
[7]	Blundell, R., & Bond, S. (1998). Initial Conditions and Moment Restrictions in Dynamic Panel Data Models. Journal of Econometrics, 87, 115-143. [Google Scholar] [CrossRef]
[8]	Ceesay, M., Jallow, B. P., & Bah, M. (2022). Droughts, Floods, and Food Availability in West Africa. African Journal of Agricultural Research, 17, 112–130. [Google Scholar] [CrossRef]
[9]	El Yacoubi, H., Boudjema, M., & Benali, M. (2021). Cereal Yields and Food Security in Sub-Saharan Africa. African Journal of Agricultural Economics, 12, 101-119. [Google Scholar] [CrossRef]
[10]	FAO (2012). The State of Food Insecurity in the World. Food and Agriculture Organisation of the United Nations.
[11]	FAO (2020). Agricultural Employment and Rural Livelihoods. Food and Agriculture Organisation of the United Nations.
[12]	FAO (2021). Food Loss and Waste in Sub-Saharan Africa: Challenges and Opportunities. FAO.
[13]	FAO (2023). Food Security Statistics. FAO.
[14]	FAO (2024). Climate Change and Agriculture in Sub-Saharan Africa. FAO.
[15]	FAOSTAT (2022). Agricultural Production and Yields Statistics. FAO.
[16]	Flanagan, A., MacIntyre, A., & O’Connell, S. (2011). Rural Dynamics and Food Insecurity in Sub-Saharan Africa. Policy Research Working Paper, The World Bank.
[17]	Han, J. W. (2025). Investigating Technological Solutions for Addressing Water Scarcity in Agricultural Production. https://arxiv.org/abs/2504.00056
[18]	Hausman, J. A. (1978). Specification Tests in Econometrics. Econometrica, 46, Article 1251.
[19]	Hossain, M., & Kim, S. (2022). Food Exports, Economic Growth, and Food Security in Developing Countries. Food Policy, 102, 102-118.
[20]	IMF (International Monetary Fund) (2020). Impact of Climate Change on GDP per Capita in Developing Countries. IMF.
[21]	IPCC (Intergovernmental Panel on Climate Change) (2021). Special Report on Climate and Food Security. IPCC.
[22]	Lima, P., Silva, J., & Costa, R. (2024). Environmental Vulnerability Index and Food Security. Environmental Economics Review, 15, 88-105. [Google Scholar] [CrossRef]
[23]	Liu, J., You, L., Amini, M., Obersteiner, M., Herrero, M., Zehnder, A. J. B. et al. (2010). A High-Resolution Assessment on Global Nitrogen Flows in Cropland. Proceedings of the National Academy of Sciences, 107, 8035-8040. [Google Scholar] [CrossRef] [PubMed]
[24]	Lobell, D. B., Schlenker, W., & Costa-Roberts, J. (2011). Climate Trends and Global Crop Production since 1980. Science, 333, 616-620. [Google Scholar] [CrossRef] [PubMed]
[25]	Misselhorn, A., & Schipper, E. L. F. (2012). Vulnerability of African Agriculture to Climate Variability. Global Environmental Change, 22, 56-65.
[26]	Mundlak, Y. (1978). On the Pooling of Time Series and Cross Section Data. Econometrica, 46, 69-85. [Google Scholar] [CrossRef]
[27]	Muriu, P., & Tadesse, G. (2020). Small-Scale Irrigation and Maize Yields in Ethiopia. Agricultural Water Management, 239, Article 106234.
[28]	North, D. C. (1990). Institutions, Institutional Change and Economic Performance. Cambridge University Press. [Google Scholar] [CrossRef]
[29]	Schultz, T. W. (1964). Transforming Traditional Agriculture. Yale University Press.
[30]	Sen, A. (1981). Poverty and Famines: An Essay on Entitlement and Deprivation. Oxford University Press.
[31]	Smith, R., & Jones, T. (2021). ND-GAIN Index and Food Security Implications. Climate Risk Management, 32, Article 100115.
[32]	Solidarités International (2020). Climate Change and Food Insecurity in Sub-Saharan Africa. Solidarités International.
[33]	Souley, A. B., & Bita, A. (2024). The Effects of Economic Integration on Food Security in Sub-Saharan Africa: An Innovative Analysis of Food Availability Using the Generalised Moments Method in Dynamic Panels. Alternatives Managériales & Economiques, 16, 89-110.
[34]	Swamy, P. A. V. B. (1970). Efficient Inference in a Random Coefficient Regression Model. Econometrica, 38, 311-323. [Google Scholar] [CrossRef]
[35]	Tadesse, G., & Alimi, T. (2020). The Role of Imports in Regional Food Security in Africa. Agricultural Economics, 51, 673-686.
[36]	Turner, B. L., Kasperson, R. E., Matson, P. A., McCarthy, J. J., Corell, R. W., Christensen, L. et al. (2003). A Framework for Vulnerability Analysis in Sustainability Science. Proceedings of the National Academy of Sciences, 100, 8074-8079. [Google Scholar] [CrossRef] [PubMed]
[37]	Van der Wiel, K. (2022). High-Resolution Climate Data and Cereal Yield Variability in Africa. Climate Risk Management, 37, 100-115.
[38]	Wilbanks, T. J. (2007). Sustainability Science and Vulnerability Assessments. Environmental Research Letters, 2, Article 045001.
[39]	Yusuf, R., & Mutia, A. (2024). Measuring Food Availability in sub-Saharan Africa: Methodological Perspectives. Journal of African Development Studies, 9, 33-52.