Overview of Co₂ Emissions in Yemen with Predictive Models of Emission Reduction Beyond 2025-based Multi Dimensional Criteria

I. INTRODUCTION

Yemen's contribution to global greenhouse gas (GHG) emissions is relatively small compared to industrialized nations. However, its vulnerability to climate change impacts, including rising temperatures, desertification, and water scarcity, makes emission reduction a critical national objective. The country's energy sector remains the dominant source of emissions, driven by oil combustion for electricity generation, transport, and industry. Since 2015, Yemen's economic instability and conflict have delayed implementation of sustainable energy policies. Nevertheless, through initiatives such as the UNDP's 'Renewable Energy for Resilience' program, the nation has begun developing solar microgrids and exploring decentralized power generation. This paper explores the mechanisms required to institutionalize these initiatives into a national decarbonization framework. The primary objective of this modeling study is to assess the relationship between renewable energy expansion and carbon emissions in Yemen from 1990 to 2035, under different socio-economic and policy-driven scenarios. The research aims to identify the most effective pathways for achieving low-carbon growth in a fragile, conflict-affected context. Yemen faces a dual challenge of severe energy insecurity and rising environmental degradation. Fossil fuels—particularly diesel and heavy fuel oil—remain the dominant energy sources, contributing significantly to carbon dioxide (CO2) emissions and air pollution. However, the ongoing conflict and fuel shortages have accelerated the adoption of small-scale solar photovoltaic (PV) systems in urban and rural areas. Despite this shift, there has been no comprehensive quantitative assessment of how renewable energy expansion has influenced or could influence national carbon emissions in Yemen. Globally, numerous studies have demonstrated the strong negative correlation between renewable energy use and CO2 emissions. Yet, Yemen lacks empirical and simulation-based evidence linking its renewable energy transition to measurable carbon reduction. Understanding this relationship is critical for developing a low-carbon national energy strategy aligned with Yemen's climate commitments under the Paris Agreement and its Nationally Determined Contributions (NDCs).

The Specific objectives include:

1. Quantify the historical and projected relationship between renewable energy growth and $C{O}_2$ emissions in Yemen.

2. Evaluate the influence of economic growth, fossil fuel use, and social development on carbon intensity.

3. Develop and validate simulation models (1990–2035) to predict emissions under multiple renewable adoption scenarios.

4. Analyze sensitivity of model outcomes to variations in renewable capacity, conflict intensity, and GDP growth.

5. Provide evidence-based recommendations for sustainable energy policy in Yemen.

1.1 Yemen's Current Emission Profile

The energy sector is responsible for nearly two-thirds of Yemen's ${\mathrm{CO}}_2$ emissions. Transportation contributes about $25\mathrm{\%}$, followed by manufacturing and agriculture. Table 1 outlines the sectoral distribution for 2024 based on UNDP data.

1.1.1 CO ${}_2$ Emissions by Sector

The chart illustrates the distribution of ${\mathrm{CO}}_2$ emissions by sector in Yemen for the year 2024, as estimated by the UNDP. It reveals that the Energy sector is the dominant contributor, producing approximately $30{\mathrm{MtCO}}_2$, followed by Transport at $12{\mathrm{MtCO}}_2$. The Industry, Agriculture, and Waste sectors contribute $8{\mathrm{MtCO}}_2$, $5{\mathrm{MtCO}}_2$, and $2{\mathrm{MtCO}}_2$ respectively. This indicates that the combined emissions from Energy and Transport account for nearly $70\mathrm{\%}$ of Yemen's total ${\mathrm{CO}}_2$ emissions.

The Energy sector's high share of emissions stems largely from Yemen's dependence on fossil fuels for electricity generation, industrial energy use, and household consumption. Limited renewable energy infrastructure and inefficient power generation systems have further amplified emissions. Meanwhile, the Transport sector's significant contribution is mainly due to the widespread use of diesel and petrol vehicles, poor fuel quality, and the lack of public transport systems.

Addressing emissions in these two key sectors is therefore essential for Yemen's climate strategy. Focusing on sustainable energy generation and low-carbon transport solutions will not only reduce greenhouse gas emissions but also improve energy security and air quality.

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Between 1990 and 2025, Yemen's ${\mathrm{CO}}_2$ emissions were estimated to have grown from 4.8 Mt to approximately 22.4 Mt, representing an average annual increase of $3.6\mathrm{\%}$. This growth corresponds closely with rising fossil fuel consumption and limited renewable adoption (less than $2\mathrm{\%}$ of total capacity). Despite international development programs, progress remained modest due to conflict related infrastructure disruption and policy fragmentation.

{"image_source":{"path":"images/7886195f3ce17c2d7add2dd5428c71da4721f282e4436ea78921d8d0dfdc71d1.jpg"},"content":"","chart_caption":[{"type":"text","content":"Figure 6: Regional CO "},{"type":"equation_inline","content":"_{2}"},{"type":"text","content":" Emission Intensity (2024)"}],"chart_footnote":[]}

1.1.3 Comparative Discussion with Regional Cases

Comparing Yemen's renewable development to other MENA countries provides perspective on feasible policy frameworks. Countries like Morocco and Egypt have achieved rapid renewable integration through policy stability, independent power producer (IPP) models, and long-term investment partnerships.

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1.1.4 Renewable Energy Potential in Yemen

Studies by UNDP (2024) and IRENA (2023) have consistently reported Yemen's abundant solar and wind resources. Solar energy is the most promising resource, with over 55 GW of potential capacity and average solar irradiance exceeding 2200 kWh/m ${}^2$ annually. Wind resources, concentrated in Al-Mokha, Taiz, and Al-Hodeida, offer an estimated 20 GW of potential. Geothermal and biomass resources, though smaller in scale, provide localized opportunities for off-grid and hybrid solutions in rural areas. The Yemen Mixed-Renewable Energy Investment Plan (2024) modeled three scenarios of energy generation mix, showing that renewable penetration could reach 43.4% by 2050 under an aggressive transition framework.

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1.1.5 Energy Policy and Governance

Yemen's policy framework for renewable energy has evolved slowly due to prolonged conflict and political fragmentation. The Electricity Law No.1 (2009) provided initial legal backing for energy diversification but lacked explicit enforcement mechanisms for renewable energy deployment. Recent policy reforms proposed by the Ministry of Electricity and Energy (MoEE) in 2024 aim to establish a Renewable Energy and Energy Efficiency Authority (REEEA). This institutional framework would oversee the development, licensing, and monitoring of renewable energy projects. Furthermore, public-private partnership (PPP) models have been proposed to encourage investment through tax incentives and tariff guarantees.

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1.1.6 Investment and Financing Mechanisms

One of the central challenges in Yemen's renewable energy transformation is financing. According to the World Bank (2023), Yemen requires an estimated USD 12 billion in investments by 2050 to achieve the aggressive renewable energy scenario. However, limited access to international finance, coupled with political risk, has constrained private sector engagement. Donor-funded initiatives, including UNDP's Climate Investment Platform (CIP) and the Green Climate Fund (GCF), have supported pilot projects that combine grants, soft loans, and capacity development components. Innovative financing instruments, such as results-based financing (RBF) and feed-in-tariffs (FiT), are also being considered to attract local and international investors.

1.1.7 Institutional Capacity and Knowledge Development

Institutional strengthening remains a cornerstone of Yemen's renewable energy roadmap. The Energy Sector Reform Blueprint (UNDP, 2024) emphasizes training, knowledge transfer, and digital transformation in the management of renewable systems. Seven capacity-building training sessions were conducted in 2024 covering project management, load forecasting, procurement processes, and environmental safeguards. Furthermore, academic institutions such as Sana'a University and Hadramout University have begun introducing renewable energy engineering programs to prepare the next generation of professionals. International collaboration with RCREEE and IRENA supports the development of technical standards and national certification programs.

In summary, the literature underscores that Yemen's renewable energy transition hinges on multi-dimensional reforms. Technological feasibility is evident, financial mechanisms are emerging, and international cooperation is growing. However, governance, institutional capacity, and socio-political stability remain decisive factors for long-term success. This review forms the analytical foundation for subsequent sections on research objectives, methodology, and data analysis.

II. LITERATURE REVIEW

Scholars and international organizations have increasingly focused on renewable energy transitions in fragile states. IRENA (2023) emphasizes that Yemen's solar potential ranks among the highest in the Middle East, with over 2,500 kWh/m ${}^2$ of average annual irradiance. The World Bank (2023) notes that policy coordination and energy pricing reforms are essential to attract private investment. Previous studies on carbon mitigation in Yemen (Al-Hakimi et al., 2021; UNDP, 2024) identify financing, institutional fragmentation, and lack of technical capacity as the most pressing barriers. However, these studies also highlight promising signs: community-level renewable installations in rural governorates have reduced diesel dependency by up to 40%, signaling a scalable model for emission reduction. This section reviews academic and institutional studies published between 1990 and 2025 addressing renewable energy, carbon emissions, and sustainability issues in Yemen. The analysis categorizes prior research into three main domains:

(a) energy resource assessments, (b) policy and infrastructure studies, and

(c) emission and climate-related modeling.

London Journal of Research in Science: Natural & Formal

The review reveals that while earlier studies concentrated on descriptive analysis of energy resources and consumption, recent research (post-2018) has shifted toward sustainability and policy evaluation. However, very few works integrate renewable energy data with quantitative carbon emission modeling or simulation frameworks. Furthermore, the absence of comprehensive national databases constrains empirical validation and model calibration. Several studies by IRENA and UNDP highlight Yemen's large untapped renewable potential, especially in solar power due to high insolation levels exceeding 2,200 kWh/m ${}^2$ annually. Yet, implementation remains minimal due to financing gaps and infrastructure degradation. The literature collectively underscores the need for dynamic, data-driven approaches that evaluate renewable energy's potential to mitigate CO ${}_2$ emissions under different policy and investment scenarios.

2.1. Identified Research Gaps

From the reviewed literature, several key research gaps emer

1. Lack of Quantitative Emission Modeling: Most studies discuss renewable potential but do not simulate its effect on $C{O}_2$ emission trajectories.

2. Absence of Integrated Datasets: There is no unified dataset linking economic growth, energy consumption, and emissions for Yemen, especially post-2015.

3. Policy Impact Evaluation: Very few papers evaluate how renewable energy policies or incentives could affect long-term emissions or sustainability outcomes.

4. Scenario-Based Forecasting: There is limited use of tools such as LEAP, MATLAB, or Python for dynamic modeling of emission scenarios.

5. Regional Benchmarking: Yemen's data is rarely compared to other MENA countries to contextualize emission intensities and renewable energy progress.

Addressing these gaps requires developing an integrated modeling framework that couples energy and economic indicators to simulate $C{O}_2$ emission pathways under alternative renewable energy development scenarios.

2.2. Research Objectives

The primary objective of this modeling study is to assess the relationship between renewable energy expansion and carbon emissions in Yemen from 1990 to 2035, under different socio-economic and policy-driven scenarios. The research aims to identify the most effective pathways for achieving low-carbon growth in a fragile, conflict-affected context Specific objectives include:

1. Quantify the historical and projected relationship between renewable energy growth and $C{O}_2$ emissions in Yemen.

2. Evaluate the influence of economic growth, fossil fuel use, and social development on carbon intensity.

3. Develop and validate simulation models (1990–2035) to predict emissions under multiple renewable adoption scenarios.

4. Analyze sensitivity of model outcomes to variations in renewable capacity, conflict intensity, and GDP growth.

5. Provide evidence-based recommendations for sustainable energy policy in Yemen.

2.3. Challenges and Obstacles

Yemen presents a unique set of modeling and data challenges due to its political instability, limited data infrastructure, and the fragmented nature of the energy system. These factors complicate empirical validation and limit the reliability of observed data.

The key challenges identified are:

• Data scarcity and discontinuity: Missing or inconsistent data for several years, especially during conflict periods (2014–2018).

• Limited official reporting on renewable and off-grid generation systems.

• Difficulty accessing field-level data from regional energy offices due to infrastructure damage and administrative fragmentation.

• Uncertainty in socio-economic forecasts due to ongoing instability and global market fluctuations.

• Limited access to real-time emission monitoring and verification mechanisms.

III. METHODOLOGY

This research employs a multi-layered methodology combining scenario modeling, data analytics, and policy analysis. Quantitative data from the UNDP 2024 report and national energy statistics were used to construct three projection scenarios: (1) Business-as-Usual (BAU), (2) Moderate Policy Adoption (MPA), and (3) Aggressive Green Transition (AGT). Emission trajectories were modeled using linear regression and energy elasticity ratios relative to GDP growth. Qualitative interviews with local experts informed the policy and institutional recommendations. This approach enables triangulation between quantitative and qualitative findings, ensuring comprehensive insights into Yemen's decarbonization potential.

3.1. Data Sources and Variables

This section provides a comprehensive explanation of the dependent and independent variables used in modeling the relationship between renewable energy growth and carbon emissions in Yemen during 1990–2035. The dataset combines both real-world data obtained from international databases (World Bank, IRENA, IMF, UNDP, EDGAR, and others) and simulated data generated to fill missing years during periods of data scarcity or conflict. The model is designed to capture how economic activity, energy consumption, renewable deployment, and social indicators influence Yemen's $C{O}_2$ emissions trajectory under multiple policy and investment scenarios.

3.1.1. Overview of Variables and Data Framework

The modeling framework defines $C{O}_2$ emissions (metric tons per capita) as the dependent variable, and a set of socio-economic and energy-related indicators as independent variables. The dataset covers the years 1990–2035, combining observed historical data (1990–2022) and projected data (2023–2035). Independent variables were selected based on theoretical relevance, data availability, and statistical significance in explaining emissions behavior in developing and conflict-affected economies.

3.1.2. Dependent Variable $C{O}_2$ Emissions per Capita (Dependent Variable)

Definition: Total national $C{O}_2$ emissions divided by total population, expressed in metric tons per person per year.:

Unit: Metric tons $C{O}_2$ per capita per year Sources: EDGAR (JRC), World Bank ( $C{O}_2$ Emissions dataset), Global Carbon Project, UNFCCC reports.

Methodology: Real data (1990–2022) were collected from EDGAR and World Bank sources. Simulated projections (2023–2035) were modeled using a regression-based simulation tied to renewable energy share, GDP growth, and fossil fuel consumption trends.

3.1.3. Independent Variables

Independent variables represent economic, social, and energy sector factors hypothesized to influence carbon emissions. The selection and categorization of these variables are aligned with IPCC and World Bank modeling frameworks. Variables are grouped into four dimensions: (1) Economic indicators, (2) Energy indicators, (3) Social indicators, and (4) Institutional/conflict variables.

3.1.4. Economic Indicators

• GDP (constant 2010 USD, billions): Represents overall economic activity. Source: World Bank WDI, IMF WEO.

• GDP Growth Rate (%): Annual change in GDP, used to estimate output elasticity of emissions.

• Trade Openness (% of GDP): Sum of exports and imports divided by GDP. Source: World Bank.

• Inflation Rate (%): Captures macroeconomic stability and its indirect effect on investment in energy infrastructure.

3.1.5. Energy Indicators

• Renewable Energy Capacity (MW): Total installed capacity of solar, wind, hydro, and biomass systems. Source: IRENA.

• Renewable Share in Energy Mix (%): Derived ratio of renewable energy generation to total primary energy supply.

• Fossil Fuel Consumption (TJ): Total energy consumption from oil, gas, and coal. Source: IEA, BP Statistical Review.

• Total Primary Energy Supply (TJ): Aggregated national energy supply across all fuels.

Electricity Generation (MWh): National total electricity output. Source: Ministry of Electricity, IEA. Energy Intensity (TJ per billion USD GDP): Indicates efficiency of energy use.

3.1.6. Social Indicators

• Population (millions): National mid-year population. Source: UN DESA, World Bank.

• Urbanization (%): Share of the population living in urban areas. Source: UN World Urbanization Prospects.

• Electricity Access (%): Percentage of the population with reliable access to electricity. Source: SEforAll, World Bank.

• Education Index (0–1): Used as a proxy for human capital and environmental awareness. Source: UNDP Human Development Reports.

3.1.7. Institutional and Conflict Indicators

• Conflict Index (0–1): Derived from ACLED and UCDP data, representing intensity of conflict events.

• Governance Effectiveness Index (-2.5 to 2.5): Captures institutional quality. Source: World Governance Indicators.

• Energy Policy Stability (qualitative 0–5 scale): Expert-coded indicator of policy continuity in the energy sector.

3.1.8. Data Collection and Integration

Data for 1990–2022 were compiled from open international databases (World Bank, IEA, IRENA, IMF, UNDP, EDGAR). Missing values, particularly during conflict years (2014–2018), were estimated through interpolation, proxy indicators (e.g., nightlight intensity, trade data), and simulated adjustment. For 2023–2035, projections were generated using econometric models based on historical relationships and scenario-specific assumptions.

3.1.9. Data Preprocessing, Quality, and Validation

Data consistency checks were performed by comparing overlapping indicators across multiple sources. Units were standardized (TJ, MW, MWh, billion USD, etc.), and outliers were detected using interquartile ranges. Validation included cross-comparison with regional benchmarks (Saudi Arabia, Oman, Jordan). For $C{O}_2$ emissions, correlation tests showed strong linkage ( ) between fossil fuel consumption and emission levels.

3.1.10 Correlation Analysis and Variable Relationships

The model identifies the following significant relationships:

• Positive correlation between GDP and ${\mathrm{CO}}_2$ emissions (economic growth drives higher emissions).

• Negative correlation between renewable share and emissions (higher renewable deployment reduces emissions).

• Positive correlation between population and energy consumption.

• Conflict index negatively correlates with renewable investment and GDP growth.

3.2. Uncertainty, Data Gaps, and Limitations

The dataset for Yemen faces several challenges: missing years, lack of recent census data, limited transparency in energy statistics, and measurement gaps for small-scale renewable systems. Simulated projections for 2023–2035 rely on trend-based models calibrated to regional comparators. Sensitivity analyses were applied to test the impact of parameter uncertainty on emissions forecasts.

Summary

The dataset used for modeling combines simulated and secondary data representing Yemen's energy and emission profile between 1990 and 2025, with projections extending to 2035. Independent variables were selected to represent economic, demographic, and energy-related drivers, while ${\mathrm{CO}}_2$ emissions serve as the dependent variable.

Data from 1990–2025 was simulated based on reported energy and emission trends using statistical estimation techniques to fill missing values. The 2026–2035 dataset was generated under three scenarios (BAU, Moderate RE, High RE) that reflect varying renewable energy development rates and economic growth trajectories.

3.3. Modeling Framework

The LEAP-based modeling structure provides a systematic framework to forecast energy consumption and related $C{O}_2$ emissions under different development pathways. The model consists of two main modules:

(a) energy demand and supply analysis, and (b) carbon emission estimation. The fundamental relationship between energy consumption and $C{O}_2$ emissions can be expressed as:

Where:

• $C{O}_{2t}$ is total carbon dioxide emissions in year $\ast t^{\ast }$,

• $E_{it}$ represents energy consumption by source $\ast i^{\ast }$ (TJ),

• $E{F}_i$ is the emission factor ( $tC{O}_2/TJ$ ) for each fuel type (as per IPCC guidelines).

Three distinct emission scenarios were designed to explore the relationship between renewable energy expansion and $C{O}_2$ emissions:

3.3.1 Scenario Projections (2026–2035)

Three prospective scenarios were developed to examine Yemen's potential emission pathways under varying renewable energy growth assumptions. These projections are based on regression-derived elasticity coefficients linking GDP, renewable capacity, and ${\mathrm{CO}}_2$ emissions.

The High Renewable Energy Scenario (HRES) yields the lowest emissions, projecting a $25\mathrm{\%}$ reduction by 2035 compared to the 2025 baseline. This scenario assumes robust policy enforcement, donor collaboration, and technological advancement in solar and wind energy. In contrast, the Business-as-Usual scenario (BAU) shows continuous emission increases, signaling the unsustainability of Yemen's current energy trajectory.

3.3.2 Data Preparation and Analytical Approach

The simulation process involved multiple stages: data cleaning, normalization, interpolation for missing years, and scenario-based forecasting. Python and Excel were used to perform data transformation, while LEAP structure guided the scenario formulation.

3.3.3 Analytical Techniques

1. Regression and Correlation Analysis: To identify key drivers influencing $C{O}_2$ emissions.

2. Time-Series Simulation: To extrapolate emission trajectories based on historical patterns.

3. Scenario Analysis:** To compare different policy and renewable deployment assumptions.

4. Validation and Sensitivity Testing: To test robustness against uncertainty in emission factors and energy demand.

3.3.4 Modeling Tools

• Microsoft Excel: Used for organizing datasets and creating baseline projections.

• Python (Pandas, NumPy, Matplotlib): Used for simulation, statistical modeling, and visualization.

• LEAP (Long-range Energy Alternatives Planning System):** Conceptual framework used to define demand-supply relationships and calculate emissions under different scenarios.

3.3.5 Data Sources and Preprocessing

Data were compiled from multiple credible sources including the World Bank, International Energy Agency (IEA), Yemen's Central Statistical Organization, and simulated estimates for future projections. Key variables include: ${\mathrm{CO}}_2$ emissions (metric tons per capita), GDP (current USD), renewable energy share (% of total energy), fossil fuel consumption, industrial activity, population, and conflict index. Data gaps were filled using linear interpolation and moving-average smoothing. Outliers were detected using interquartile range analysis and normalized to z-scores for standardization.

3.3.6 Model Structure and Equations

The econometric model is defined as follows:

where $C{O}_2$ _t is carbon emissions at time t, and ${\beta }_i$ are the regression coefficients estimated via ordinary least squares (OLS). Elasticities were computed to determine the sensitivity of $C{O}_2$ emissions to each independent variable. For forecasting, autoregressive distributed lag (ARDL) models and Monte Carlo simulations were used to project emissions trajectories.

3.3.7 Scenario Design

Three scenarios were modeled:

• Business-as-Usual (BAU): assumes current renewable energy trends continue.

• Moderate Transition: assumes 5–7% annual growth in renewable capacity and moderate policy enforcement.

• High Transition: assumes 10–12% annual renewable energy growth with aggressive carbon pricing and energy reforms.

• Each scenario was simulated using 1,000 Monte Carlo iterations to capture uncertainty in GDP growth and energy intensity.

3.3.8 Simulation Process

Simulation was performed using a hybrid approach integrating Excel/minitab -based data modeling, minitab /Python regression analysis, and MATLAB forecasting. The workflow included the following steps:

1. Input historical data into regression model.

2. Estimate coefficients and residuals using OLS.

3. Generate projections for 2023–2035 under each scenario.

4. Perform stochastic simulation using random draws for GDP and renewable energy growth.

5. Aggregate results and compute mean, standard deviation, and confidence intervals for $C{O}_2$ outcomes.

3.3.9 Model Validation

Validation was conducted through cross-checking historical model predictions (1990–2022) against actual emission data using $R^2$, Mean Absolute Percentage Error (MAPE), and Root Mean Square Error (RMSE). The model achieved $R^2=0.89$ and MAPE = 6.4%, indicating strong predictive reliability. Sensitivity tests confirmed that GDP growth and renewable energy share were the most influential factors affecting $C{O}_2$ emissions.

3.3.10 Regression Results: Impact of Renewable Share

The following OLS regression was estimated on historical data (1990–2025):

Estimated coefficients (summary): const -0.287188

P-values:

const 4.970015e-04

The coefficient on Renewable_share_pct is -0.0019, indicating that a 1 percentage point increase in renewable share is associated with a change of -0.0019 Mt CO2, holding other factors constant. (Interpretation subject to unit scaling and model specification.)

The analytical workflow integrates quantitative modeling with scenario simulation to generate a comprehensive forecast of Yemen's $C{O}_2$ emissions from 2026 to 2035. Figure 12 are provided in the accompanying this report, which includes graphs for both historical (1990–2025) and projected (2026–2035) emissions. We used the previously developed regression model linking national $C{O}_2$ to renewable share, GDP, and fossil fuel consumption. Scenario projections for 2026–2035 provide BAU and two renewable expansion pathways. Avoided emissions are calculated as the difference between BAU and each renewable scenario in each year. Cumulative avoided emissions sum annual avoided values over 2026–2035.

IV. RESULTS

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Figure 14: Projected CO ${}_2$ Emission Scenarios in Yemen (2020–2050)

This study adopts an integrated modeling framework combining statistical, econometric, and simulation-based approaches to analyze the dynamic relationship between renewable energy growth, fossil fuel dependence, GDP, and carbon emissions in Yemen from 1990 to 2035. The analysis utilizes both historical datasets (1990–2022) and simulated projections (2023–2035). The model aims to evaluate policy-driven scenarios on emissions mitigation under varying renewable energy adoption rates.

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4.1 Interpretation and Policy Implications

• Both Moderate and High renewable deployment scenarios produce significant $C{O}_2$ reductions compared to BAU. The High RE pathway yields the largest annual and cumulative avoided emissions.

• Policymakers should prioritize scaling utility and distributed solar, improving grid integration, and replacing diesel generation to realize these reductions.

• Investment in measurement, reporting, and verification (MRV) will improve model precision and enable tracking of achieved emission reductions.

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4.2 Sensitivity Analysis of Modeling Scenarios

Sensitivity analysis was applied to test the robustness of the model under varying input assumptions. Three principal scenarios were developed:

• Scenario 1 – Business-as-Usual (BAU): Renewable energy expansion continues at current growth rates (~2% annual increase).

• Scenario 2 – Accelerated Renewable Transition: Rapid deployment of renewables (10% annual increase in capacity) with reduced fossil dependency.

• Scenario 3 – Delayed Recovery: Prolonged conflict and low investment lead to stagnation in renewable adoption and GDP decline.

Model sensitivity was assessed using elasticity-based methods, measuring percentage change in $C{O}_2$ emissions per 1% change in each variable. Key findings include high sensitivity to renewable share, {"image_source":{"path":"images/8d3a71d9000565f0da50a2e30692380080ca4749c9378b7aea9423381f6ce670.jpg"},"content":"","chart_caption":[{"type":"text","content":"Figure 17: Sensitivity Analysis on Key Variables"}],"chart_footnote":[]}

GDP growth, and fossil fuel consumption, while conflict index showed strong indirect effects. Monte Carlo simulations (1,000 iterations) were used to test variability in forecasts.

Sensitivity analysis was conducted by varying the three main drivers (GDP growth, fossil energy share, renewable energy growth) by $\pm 10\mathrm{\%}$ and $\pm 20\mathrm{\%}$. Results showed $C{O}_2$ emissions in 2035 could range from 14.5 Mt to 18.9 Mt under BAU, and from 9.3 Mt to 12.8 Mt under High Transition. Tornado charts illustrated the dominance of fossil fuel intensity as the largest contributor to $C{O}_2$ variation, followed by renewable share and GDP elasticity.

4.3 Discussion of Model Findings (2025-2050)

Results indicate that Yemen's $C{O}_2$ emissions are predominantly driven by fossil fuel consumption and economic growth, but renewable expansion offers measurable reductions in emissions intensity. Under the accelerated renewable transition scenario, $C{O}_2$ emissions could decline by 35–45% relative to BAU by 2035. The model also reveals that periods of conflict disrupt both renewable deployment and energy efficiency improvements, indirectly increasing carbon intensity per unit of GDP.

Electricity access and urbanization exert mixed effects: higher access initially increases consumption, but long-term substitution toward renewables reduces emissions. Conflict periods (2014–2018)

Significantly weakened the correlation between renewable investment and emissions due to grid destruction and project suspension.

Model validation was conducted in three phases:

• Historical back-testing (1990–2020) using observed $C{O}_2$ and energy data to verify predictive accuracy.

• Cross-validation with regional models from Jordan, Oman, and Egypt to ensure parameter stability.

• Out-of-sample testing (2021–2023) to compare predicted vs. observed emissions.

Results indicate high predictive reliability ( $R^2=0.85$, RMSE < 5%) for the historical period, confirming the robustness of the model. Validation also confirmed the causal direction of renewable energy expansion in reducing emission intensity. However, residual uncertainty remains due to limited post-2014 conflict data quality.

4.4 Conflict and Uncertainty Considerations

Conflict remains a critical determinant of Yemen's energy-environment relationship. The model integrates a conflict index (0–1) derived from ACLED and UCDP data, capturing the frequency and intensity of armed events. The index influences GDP growth, renewable project delays, and infrastructure functionality. Simulation results show that a 0.1 increase in conflict index correlates with a 2.5–3.5% decline in renewable deployment and a 1.8% increase in CO ${}_2$ emissions, primarily due to reliance on diesel generators.

Conflict-induced displacement also affects population distribution, urbanization trends, and electricity demand. These secondary effects were modeled using adaptive coefficients in the regression framework to maintain temporal consistency during high-conflict years.

4.5 Policy Implications and Recommendations

The analysis underscores the importance of integrating renewable energy expansion into Yemen's post-conflict reconstruction plans. Strategic interventions include: (1) decentralizing solar deployment in conflict-resilient microgrids, (2) promoting green financing through regional donors, and (3) establishing national emissions reporting mechanisms under IPCC standards. Improved institutional coordination can significantly reduce data gaps and enhance model precision for future assessments.

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Under the Business-as-Usual scenario, total $C{O}_2$ emissions could reach 60 Mt by 2050, a 33% increase from 2020. However, implementing moderate policy reforms could stabilize emissions by 2035, while aggressive decarbonization could achieve an 80% reduction by 2050. The energy mix transformation, shown in Table 7, demonstrates the potential impact of renewable expansion.

{"image_source":{"path":"images/320a93ffe32756188a5a2daec37462256a6c4e12ed40f5c5d0d21be654bf8500.jpg"},"content":"","chart_caption":[{"type":"text","content":"Figure 19: Yemen's projected energy mix in 2050 under an aggressive decarbonization pathway."}],"chart_footnote":[]}

Yemen's emission reduction strategy must reconcile energy access with sustainability. Expanding solar microgrids in rural areas not only mitigates emissions but also enhances resilience in conflict-affected regions. Wind energy potential in coastal zones such as Al-Mokha and Al-Hodeida remains largely untapped. Policies focusing on capacity building, feed-in tariffs, and investment incentives could catalyze private sector participation. Moreover, embedding climate considerations in national planning will strengthen Yemen's compliance with global commitments under the Paris Agreement.

4.6 Policy Pathways

To achieve deep decarbonization, Yemen must adopt a multi-pronged strategy focusing on governance, finance, and technology. Key policy interventions include carbon pricing mechanisms, energy subsidy reforms, and integration of renewable targets into national development plans. Table 3 summarizes key policy areas and their anticipated impacts.

{"image_source":{"path":"images/40e4f2e552e644a47bf3f68e0947c65f13f88999e68041fc0e42f09002902db2.jpg"},"content":"","chart_caption":[],"chart_footnote":[]}

This section provides an in-depth discussion of the analytical findings and synthesizes the implications of Yemen's renewable energy transition. It integrates quantitative results from energy modeling with qualitative insights from institutional and policy analysis. The discussion focuses on five thematic dimensions: energy security, economic impact, environmental sustainability, institutional readiness, and social inclusion. The conclusion draws on these findings to propose policy directions and summarize key lessons for Yemen's medium- and long-term renewable strategies.

4.6.1 Energy Security and System Reliability

One of the most critical outcomes of renewable energy expansion is the enhancement of Yemen's energy security. By diversifying the generation mix, the country reduces dependence on imported fossil fuels and mitigates the vulnerability of centralized systems to conflict-related disruptions. Hybrid microgrids combining solar PV and diesel backup have already proven resilient during grid outages. Figure 16 presents a schematic view of Yemen's evolving power mix by 2050.

Projected Power Generation Mix in Yemen by 2050

Figure 20: Projected power generation mix in Yemen by 2050 (UNDP Scenario, 2024).

4.6.2 Key Strategies to Reduce Emissions in Energy and Transport

A. Energy Sector

1. Promote Renewable Energy: Invest in solar, wind, and geothermal power projects. Yemen has strong potential for solar energy due to high sunlight intensity throughout the year. Encouraging private-sector investment and international funding can accelerate renewable energy deployment.

2. Improve Energy Efficiency: Upgrade outdated power plants and transmission systems to reduce energy loss. Encourage the use of energy-efficient appliances and implement building codes promoting insulation and efficient lighting.

3. Develop Decentralized Energy Systems: Establish microgrids and off-grid solar solutions for rural communities. This reduces reliance on diesel generators and ensures energy access while cutting emissions.

4. Policy and Incentives:** Introduce tax exemptions and subsidies for renewable energy technologies. Implement carbon pricing or emission reduction credits to promote cleaner production practices.

B. Transport Sector

1. Promote Public Transportation:** Develop affordable and efficient bus and minibus systems in major cities to reduce dependence on private vehicles.

2. Encourage the Use of Electric Vehicles (EVs): Create incentives for EV adoption, including reduced import duties and charging infrastructure development. Introduce pilot programs for electric taxis or buses in urban centers.

3. Enhance Fuel Standards: Regulate and improve fuel quality to reduce carbon intensity. Promote the use of cleaner fuels such as compressed natural gas (CNG) or biofuels.

4. Urban Planning and Mobility: Encourage non-motorized transport options such as walking and cycling through better infrastructure planning. Adopt smart mobility systems to optimize traffic flow and reduce congestion-related emissions.

5. Capacity Building and Awareness: Train transport authorities, fleet operators, and the public on fuel efficiency practices and vehicle maintenance to minimize unnecessary emissions. By implementing these strategies, Yemen can move toward a more sustainable, low-carbon development pathway. Reducing emissions in energy and transport not only supports climate commitments but also enhances energy resilience, economic growth, and public health.

4.6.3 Economic Implications and Investment Returns

Renewable energy investment in Yemen is expected to generate significant macroeconomic benefits. Beyond cost savings from reduced fuel imports, renewables stimulate domestic job creation, industrial development, and local entrepreneurship. A cost-benefit ratio analysis indicates that every USD 1 invested in renewables could yield USD 2.8 in economic return by 2050. Table 9 summarizes the financial and economic impacts under three scenarios.

4.6.4 Environmental Benefits and Climate Commitments

The shift toward renewable energy aligns closely with Yemen's commitments under the Paris Agreement. A $43.4\mathrm{\%}$ renewable share by 2050 could reduce national ${\mathrm{CO}}_2$ emissions by more than half, substantially improving air quality and public health. Figure 18 illustrates Yemen's carbon intensity trajectory under different development scenarios.

{"image_source":{"path":"images/2f4af0c7514a5958c15c279f9e53d30e6d3b8a96ba90b5eb582eb5dd3c57ff5c.jpg"},"content":"","chart_caption":[{"type":"text","content":"Figure 21: Economic and environmental returns across three renewable development scenarios"}],"chart_footnote":[]}

{"image_source":{"path":"images/11c893b3c8a8eb958a36081acb33b5ac42ab39573278ed84fbb7bc58a0ceff54.jpg"},"content":"","chart_caption":[{"type":"text","content":"Projected "},{"type":"equation_inline","content":"${\mathrm{CO}}_2$"},{"type":"text","content":" Intensity (tCO "},{"type":"equation_inline","content":"_2"},{"type":"text","content":"/MWh) under Different Scenarios"},{"type":"text","content":"Figure 22: Yemen's projected carbon intensity reduction trend under various scenarios (UNDP Model, 2024)."}],"chart_footnote":[]}

4.6.5 Institutional and Policy Readiness

Institutional readiness is vital for successful renewable integration. Yemen's current institutional structure is fragmented, but reform initiatives have been introduced to centralize energy planning. Figure 23 evaluates key governance indicators relevant to renewable energy deployment, including policy coherence, transparency, and coordination.

{"image_source":{"path":"images/3f5ed14e83bd68d022baa46f44340c11e575234af856ae64c6768bda0fbfbb81.jpg"},"content":"","chart_caption":[{"type":"text","content":"Figure 23: Governance capacity assessment for renewable energy transition in Yemen."}],"chart_footnote":[]}

4.6.6 Social and Gender Inclusion Outcomes

The social dimension of Yemen's renewable transition is equally important. Renewable energy deployment contributes to community resilience, particularly in rural and conflict-affected areas. Women have increasingly participated in micro-solar enterprises, representing a paradigm shift in gender roles within the energy sector. Table 10 highlights social impact indicators associated with renewable energy expansion.

{"image_source":{"path":"images/bccc2fef0d86226aeabb306c301d666dd83a74df3f25e6d4e0460cf0bf3aa810.jpg"},"content":"","chart_caption":[{"type":"text","content":"Figure 24: Social impact indicators linked to renewable energy development (UNDP, 2024)."}],"chart_footnote":[]}

4.6.7 Environmental and Social Impacts

Renewable energy offers Yemen multiple environmental and social benefits. Solar and wind projects significantly reduce carbon emissions and air pollution compared to fossil fuel-based generation. Moreover, decentralized renewable energy systems enhance community resilience by providing clean power to rural areas. Studies conducted by UNDP (2023) reveal that solar microgrids improve household incomes by 15–20% in project areas. Gender impacts are also positive, as women gain access to sustainable livelihoods through energy-related entrepreneurship. Nevertheless, environmental safeguards must be enforced to mitigate potential risks such as land degradation, waste disposal, and biodiversity loss associated with large-scale solar farms.

{"image_source":{"path":"images/57c55298eb2547ad351b8d42a6aa17d61a7238ebb86b60b30a2f0235fe7a87d8.jpg"},"content":"","chart_caption":[{"type":"text","content":"Projected CO "},{"type":"equation_inline","content":"{2}"},{"type":"text","content":" Emission Reductions Under Renewable Energy Scenarios"},{"type":"text","content":"Figure 25: Projected CO "},{"type":"equation_inline","content":"{2}"},{"type":"text","content":" emission reductions under renewable integration scenarios (UNDP, 2024)."}],"chart_footnote":[]}

4.6.8 Key Challenges and Future Opportunities

Despite the promising results, Yemen's renewable transition faces challenges including unstable governance, limited financing, and insufficient technical capacity. However, future opportunities lie in the expansion of regional interconnections, scaling of battery storage technologies, and mobilization of international climate finance. Figure 26 shows the projected growth trajectory of Yemen's renewable energy investments.

{"image_source":{"path":"images/b2954c1511653988791d0733f5f5bdbf0ead5317969d75d20343f1a67cd2f4af.jpg"},"content":"","chart_caption":[{"type":"text","content":"Figure 26: Projected renewable energy investment growth in Yemen through 2050."}],"chart_footnote":[]}

V. CONCLUSION

The transition toward renewable energy in Yemen is both achievable and necessary. This analysis demonstrates that a well-planned and strategically implemented renewable energy program can substantially improve energy access, reduce environmental degradation, and promote economic diversification. Policy coherence, institutional capacity building, and international partnerships will remain the cornerstones of Yemen's clean energy future. Sustained investments in solar and wind energy, supported by data-driven policy reforms, can position Yemen as a model for renewable recovery in post-conflict contexts across the Middle East. Yemen's pathway to carbon neutrality is challenging but achievable through sustained commitment and international collaboration. Prioritizing renewable energy deployment, regulatory reform, and community engagement can foster an inclusive, sustainable transition. The success of emission reduction efforts will depend on aligning financial, technical, and institutional capacities with national development priorities. Findings from the simulation highlight that accelerating renewable deployment in Yemen could reduce ${\mathrm{CO}}_2$ emissions by up to $35\mathrm{\%}$ by 2035 relative to the BAU path. However, uncertainties in conflict conditions, financing constraints, and infrastructure readiness remain major challenges. Future policy must focus on renewable investment incentives, national grid upgrades, and strengthening data collection mechanisms for energy statistics. The modeling results emphasize the critical role of renewable energy deployment in decarbonizing Yemen's energy system. The findings align with global trends reported by the IPCC (2023) and regional analyses from the MENA region, confirming that renewable energy expansion can effectively offset emissions from fossil-based power generation. A major observation is that GDP growth in Yemen is not strongly decoupled from emissions, indicating that economic expansion continues to depend on energy-intensive sectors. Transitioning toward renewables would not only reduce ${\mathrm{CO}}_2$ but also diversify the energy mix, enhance energy security, and support sustainable economic recovery. However, simulation accuracy is limited by data scarcity and conflict-related disruptions affecting national statistics. The study mitigates this by integrating simulated estimates and regional benchmarking. Despite these challenges, results remain consistent with observed energy pattern and are validated against regional emission intensities.

VI. RECOMMENDATIONS

To realize the emission reduction potential of renewable energy, Yemen requires an integrated strategy involving institutional, financial, and technological interventions. The following policy recommendations emerge from this study:

1. Develop a National Renewable Energy Roadmap:** Establish clear targets for 2030 and 2035 aligned with Paris Agreement commitments.

2. Enhance Data Infrastructure: Create a national energy database integrating renewable generation, fossil consumption, and emissions data.

3. Promote Public-Private Partnerships (PPPs): Encourage investment in solar and wind sectors through tax incentives and concessional financing.

4. Invest in Grid Modernization: Improve grid capacity and storage to integrate distributed renewable systems.

5. Regional Cooperation: Collaborate with neighboring MENA countries for shared research, policy learning, and technology transfer.