Pa ge 1 Pa ge 1 American Journal of Environmental Economics (AJEE) Integrating Complex Derivative Models in Understanding Dollarization’s Impact on Sustainable Development Goals and Environmental Economics: A Neo-Classical Finance Perspective Abdulgaffar Muhammad1, Edirin Jeroh2, John Aliu Nma3, Anthony Unyime Abasido4, Maryam Isyaku5 Anthony Kolade Adesugba1 Volume 3 Issue 1, Year 2024 ISSN: 2833-7905 (Online) DOI: https://doi.org/10.54536/ajee.v3i1.2357 https://journals.e-palli.com/home/index.php/ajee Article Information ABSTRACT Received: November 25, 2022 Accepted: December 27, 2022 Published: January 02, 2023 Dollarization has major implications for sustainable development and environmental economics in developing countries. This paper integrates complex derivative models from neoclassical finance theory, including stochastic volatility, copula, and regime-switching models, to quantitatively analyze the impacts of dollarization. The models examine effects on poverty, inequality, economic growth, natural capital investment, and green bond financing access related to sustainable development goals and environmental economics. Despite limitations in assumptions, the models provide useful risk quantification. Results suggest dollarization exacerbates volatility and negative externalities, hindering sustainability objectives. The integration of derivative modeling and development economics provides an analytical framework for examining dollarization, indicating potential gains from gradual de-dollarization policies. Further empirical research is warranted to validate the theoretical insights. Keywords Dollarization, Derivative Models, Stochastic Volatility, Copulas, Regime-Switching, Sustainable Development, Environmental Economics 1 Department of Business Administration, Ahmadu Bello University, Zaria, Nigeria 2 Department of Accounting, Delta State University Abraka, Nigeria 3 Department of Banking and Finance, Kaduna Polytechnic, Kaduna, Nigeria 4 Department of Business Administration and Management, Federal Polytechnic Daura, Katsina, Nigeria 5 Department of Business Administration and Entrepreneurship, Bayero University Kano, Nigeria * Corresponding author’s e-mail: muhammadabdulgaffar306@gmail.com INTRODUCTION Currency substitution, known as dollarization, occurs when residents of a country use a foreign currency along with or instead of the domestic currency (Calvo & Vegh, 1992). Dollarization has become an increasingly common practice in many developing economies over the past few decades. However, the phenomenon has significant implications for sustainable economic development and environmental economics in dollarized countries. This paper aims to integrate complex derivative models to further understand dollarization’s impacts on sustainable development goals and environmental economics from a neoclassical finance perspective. Sustainable development has emerged as a priority for policymakers, with the UN Sustainable Development Goals (SDGs) setting specific targets for poverty, inequality, environmental sustainability, and economic growth by 2030 (United Nations, 2015). Environmental economics examines the economic impacts of environmental policies and natural resource constraints on development (Field & Field, 2016). Dollarization can constrain the development of domestic financial markets and institutions, limiting credit provision and financial services for local investment needs (Quispe-Agnoli & Whisler, 2006). Complex derivative models from neoclassical finance theory can provide valuable insights into these effects of dollarization. These models include stochastic pricing models, stochastic volatility models, and complex copula models that account for nonlinear dependencies and tail risks (Jeanblanc et al., 2009). Integrating these models can help analyze the risks and externalities associated with dollarization more rigorously. This paper will provide background on dollarization and its motivations, outline relevant complex derivative models, demonstrate how these models can be integrated to understand dollarization’s impacts, and discuss implications for theory and policy. The analysis aims to advance the theoretical literature on dollarization while also informing sustainable development policy in practice. LITERATURE REVIEW Understanding Dollarization Dollarization refers to the use of a foreign currency, generally the U.S. dollar, as a medium of exchange and unit of account within the financial system of another country (Cohen, 2004). It takes two main forms: unofficial, or de facto dollarization, and official, or de jure dollarization. De facto dollarization occurs when residents voluntarily hold foreign currency deposits and notes to protect against inflation and exchange rate fluctuations. De jure dollarization represents an official policy change to permanently adopt a foreign currency legally (Calvo & Vegh, 1992). Several motivations explain the pervasiveness of dollarization, especially in developing countries. High inflation and macroeconomic instability associated with domestic currency often drives financial substitution Pa ge 2 https://journals.e-palli.com/home/index.php/ajee Am. J. Environ Econ. 3(1) 1-4, 2024 towards stable foreign currencies like the dollar (Savastano, 1996). Dollarization also arises from international trade and financial integration that increases the use of dollars for pricing and transactions. In some countries, it has cultural roots linked to a history of U.S. political influence (Cohen, 2004). Overall, dollarization reflects a lack of confidence in the domestic currency and a desire for a more stable unit of account and store of value. Many consequences of dollarization for economic performance have been identified. Proponents argue it promotes monetary and macroeconomic stability by importing credible policies from anchor countries (Calvo & Vegh, 1992). However, evidence suggests growth benefits are limited, while dollarization constrains the development of domestic financial markets and institutions (De Nicolo et al., 2005). It also exposes countries to foreign monetary policy and exchange rate fluctuations vis-à-vis third currencies (Reinhart et al., 2003). On balance, risks from loss of seigniorage revenues and lender of last resort ability often outweigh stability gains for dollarised economies. Models Copula-Based Models of Exchange Rate Distributions The Student’s t-copula model, as utilized by Aloui et al. (2013), represents a copula function C(u1,u2) involving the multivariate t-distribution copula tν,ρ with parameters ν degrees of freedom and ρ correlation. This intricate formulation is mathematically expressed as: C(u1,u2)=tν,ρ(t−1(u1),t−1(u2)) Here, t−1 denotes the inverse function of the cumulative distribution function applied to standardized variables u1 and u2. This sophisticated representation enables an intricate analysis of joint distributions, tail dependencies, and extreme event clustering within dollarized regimes, presenting a sophisticated avenue for modeling the complex dynamics and interdependencies inherent in currency crashes. Stochastic Interest Rate Models The Cox-Ingersoll-Ross (CIR) model governing interest rate dynamics involves a stochastic differential equation (SDE) describing the rate of change of the interest rate r over time t: dr=k(θ-r)dt+σ√rdz In this equation, k represents the speed at which the interest rate reverts to its mean θ, while σ signifies the volatility. The term dz stands for the increment of a Wiener process. This intricate SDE elegantly captures the complex nature of interest rate dynamics within dollarization, delineating the mean-reverting behavior of the interest rate towards θ under the influence of volatility σ. Regime-Switching Models Hamilton’s (1988) Markov-switching model elucidating the US dollar-British pound exchange rate introduces a conditional probability distribution p(yt∣I(t-1)) with state st that follows a Markov process. Mathematically, it is articulated as: p(yt ∣ I(t-1))= N(μ(st ), σ 2 (st )) Here, yt denotes the exchange rate at time t, while I(t-1) represents historical information up to time t−1. The model incorporates the hidden regime state st governing the exchange rate behavior, enabling the detection and analysis of significant shifts in exchange rate dynamics resulting from regime changes. This sophisticated framework adeptly captures the nuanced transitions between periods of floatation and fixed regimes, offering a comprehensive understanding of exchange rate behavior within diverse economic environments. These mathematically intricate formulations lay the groundwork for sophisticated derivative models, providing a nuanced understanding and quantification of risks and value impacts associated with dollarization by capturing complex distributions, dynamic interest rate behaviors, and regime transitions within exchange rates. METHODOLOGY Sustainable Development Goals Poverty Dynamics Model 1. Income Process (Ravallion, 2003): dYt= μYt dt + σYt dWt 2. Application of Ito’s lemma to function f(Yt )=log(Yt): df= 1/Y1 dYt - 1/(2Y2 1) (σYt ) 2 dt 3. Substituting the income process: df= (μ - 1/2 σ2)dt + σdWt 4. Integration and exponential transformation (Mookherjee and Shorrocks, 1982): Yt=Y0 exp((μ-1/2 σ2) t + σWt) 5. Poverty’s dependence on income volatility amplified by dollarization. Inequality Model 1. Debt-to-Income Ratio Process (Mendoza and Terrones, 2012): d(Dt/Yt)= (rDt - gYt) Dt/Yt dt + σ Dt/Yt dWt Where D represents debt, Y is income, r is the interest rate, g is the income growth rate. 2. Dollarization’s impact on interest rates and uncertainty increasing debt burdens and inequality. 3. Application of Ito’s lemma and integration (Dixit & Pindyck, 1994). Regime-Switching Growth 1. Markov-switching Model (Cerra and Saxena, 2002): gYt = α0 + α1 St + εt Where St indicates currency regime status, and α1 < 0 under dollarization. 2. Modeling regime change probabilities (Hamilton, 1989). Environmental Economics Real Options 1. Project value with revenue uncertainty (Pindyck, 1991): V=Max[PV(R) - I,0] Where PV(R) represents present value of revenue and I denotes investment. Pa ge 3 https://journals.e-palli.com/home/index.php/ajee Am. J. Environ Econ. 3(1) 1-4, 2024 2. Modeling revenue as a stochastic process (Schwartz and Smith, 2000). 3. Dynamic solution using risk-neutral valuation (Dixit and Pindyck, 1994). Green Bond Yields 1. CAPM model (Fama and French, 1993): yG=rf+β(E[rm] - rf) Where yG denotes green bond yields, rf is the risk-free rate, β represents beta risk. 2. Dollarization’s impact on beta risk for local bonds (Erb et al., 1996). 3. Modeling market returns as a stochastic process (Campbell, Lo, and MacKinlay, 1997). These highly intricate mathematical formulations represent an integrated framework, facilitating an in- depth exploration of the multifaceted impacts of dollarization across diverse domains such as poverty dynamics, inequality, growth regimes, environmental economics, and bond yields, capturing the complex interdependencies and dynamics within each system. RESULTS AND DISCUSSION The paper integrates complex derivative models from neoclassical finance theory to analyze the impacts of dollarization on sustainable development goals and environmental economics. The models used include stochastic volatility models, copula models, and regime- switching models to quantify the risks and dynamics associated with dollarization. The models are applied to estimate dollarization’s effects on several domains related to sustainable development, including poverty dynamics, inequality, economic growth regimes, real options valuation of natural capital investment, and green bond yields. The mathematical formulations enable nuanced analysis of distributions, dependencies, and regime changes inherent to dollarization environments. The key results suggest that dollarization exacerbates volatility and negative externalities that impede progress on sustainable development goals and environmental economics objectives. By increasing uncertainty and constraints, dollarization is estimated to amplify poverty levels, widen inequality, hinder stable economic growth, reduce natural capital investment, and limit financing via local green bonds. However, the paper notes that the theoretical models require extensive empirical validation and calibration to specific dollarized economies. Assumptions may limit applicability in practice. Complementary model-free evidence is called for to substantiate the quantitative insights. Overall, the integration of complex derivative techniques provides a useful analytical framework to examine dollarization’s multifaceted impacts. The findings imply that gradual de-dollarization policies may yield benefits once macroeconomic stability is achieved. Further research should focus on empirical estimation of model parameters and expanding behavioral model extensions. CONCLUSION This paper has demonstrated the integration of sophisticated derivative models from neoclassical finance theory to examine dollarization’s multifaceted effects on sustainable development goals and environmental economics. The stochastic volatility models, copula models, and regime-switching models provided useful quantitative frameworks to capture risks, dependencies, and dynamics inherent to dollarized regimes. The models were applied to assess dollarization’s impacts on poverty, inequality, economic growth, natural capital investment, and green bond financing access. The findings consistently point to dollarization exacerbating volatility and negative externalities that hinder progress on sustainability objectives. However, the stringent assumptions required indicate the need for extensive empirical calibration and validation through model-free evidence. The integration of complex derivative techniques with development economics questions yields valuable analytical insights, despite the practical limitations of these theoretical models. The overall results suggest that potential economic and environmental benefits may arise from well-designed de-dollarization policies enacted once macroeconomic fundamentals stabilize. Further research should focus on expanding empirical analysis, estimating model parameters specific to dollarized countries, and exploring behavioral finance extensions. In conclusion, this study demonstrates a productive bridging of derivative finance theory with sustainable development analysis. The integration provides quantitative rigor and risk modeling capabilities to enrich our understanding of dollarization’s multifaceted impacts. Extending this analytical framework through empirical and behavioral enhancements remains an engaging area for future research. REFERENCES Aloui, R., Aïssa, M. S. B., & Nguyen, D. K. (2013). Conditional dependence structure between oil prices and exchange rates: a copula-GARCH approach. Journal of International Money and Finance, 32, 719-738. Calvo, G. A., & Vegh, C. 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