تغییرات ساختاری و توسعه پایدار

In this paper, we show that the commonly observed decline in primary (natural resource using) sector output and employment shares, often termed structural change, can be explained as an endogenous response to the presence of nature's constraint. Structural change takes place even if consumer preferences are homothetic, and technological progress does not discriminate against the primary sector. Under certain conditions, structural change allows an open economy to grow with natural resource sustainability. Sustained and environmentally sustainable economic growth is possible even if the natural resource is exploited under open access. Well-defined property rights are neither necessary, nor sufficient for sustainable growth. We show that there is no unique relationship between natural resource endowment and the rate of economic growth over the long run. Resource-rich economies may grow faster or slower than resource-poor ones.

While some economists remain concerned that continuous growth places unsustainable demands on the natural resources, others believe that improving technology makes growth and environmental sustainability compatible. In this paper we revisit this issue and ask three questions. First, given a distortion-free economy that uses a renewable natural resource as factor of production, what makes sustainable growth possible? Second, if the natural resource is characterized by ill-defined property rights, a pervasive feature in many countries [11], is sustainable growth still possible? Third, is the long-run rate of economic growth affected by ill-defined property rights? We consider a small open economy which uses three assets to produce two final goods, one resource based and the other produced without using the resource. One asset is specific to the non-resource sector (“physical capital”), another is specific to the resource-based sector (natural capital) and the third asset (“human or knowledge capital”) enhances the productivity of labor in both sectors. We present an intuitive but novel explanation for sustainable growth: endogenous structural change. Structural change refers to a reduction of output and employment shares of the primary or natural resource sector during the growth process, a widely accepted stylized fact of the modern growth process [13], [24] and [26]. First we derive the conditions for sustainable development when property rights are well-defined on all assets including the natural resource, and markets are competitive using the “benevolent social planner” paradigm. Next we consider the case where the natural resource is subject to ill-defined property rights but property rights are well defined for the other two assets and markets are competitive. In both cases the model predicts a decreasing share of the primary (resource-based) sector's output in total output, a decreasing share of the total labor force employed in the primary sector, and unbalanced asset accumulation causing a continuous change in the composition of factors of production toward those most intensively used by the non-primary sectors. The model thus predicts a broader version of structural change than usual. We also find that labor productivity grows in both the resource and non-resources sectors. These predictions seem consistent with well accepted stylized facts.1 We also show that property rights on the natural resource are neither necessary nor sufficient for sustainable economic growth. Lack of property rights cause a lower equilibrium level of the natural resource (and a lower welfare level at each point in time) but their absence threatens neither the feasibility nor the actual rate of economic growth over the long run. That is, the equilibrium rate of economic growth is unrelated to the level of natural resource endowment; resource-rich countries may not grow any faster over the long run than resource-poor ones. Intuitively, structural change is an endogenous response to the nature's constraint which implies that the natural resource remains constant over the long run. Even if technical change has identical impacts across sectors, growth in the productivity of man-made assets in the primary sector cannot match the growth in productivity in the non-resource sector where all assets continuously expand over time. This implies that the non-resource sector is able to continuously pull labor from the primary sector and to grow faster than the primary sector. Under open access, there is no investment in the natural asset, and the natural resource is over-harvested. However, despite these problems, labor market interactions preserve structural change and the level of the natural resource also remains constant over the long run, albeit at a lower level than under perfect property rights. Given well functioning markets elsewhere, increases in man-made capital still imply a divergence of productivity growth across the two sectors. To maintain equilibrium in the labor market, labor is drawn towards the non-resource sector. The result that optimal environmental policy is not necessary for sustainable growth is in sharp contrast with the findings by the literature focusing on pollution rather than renewable natural resources, in which optimal environmental policy is a necessary condition for sustainable growth [1] and [38]. The reason is that this literature assumes that pollution only affects the utility function but it has no feed-back (negative) effects on the productivity of the production sector. Thus, in the absence of environmental policy that imposes a cost to pollution emissions, firms have no incentives to restrain emissions; sustainable growth is, therefore, infeasible. By contrast, when the environment is also a factor of production, as the natural resource becomes scarcer firms have an incentive to substitute and to shift toward non-resource using sectors. The literature on sustainable growth is, with a few exceptions, based on models with a single final good where the growth of income and environmental damage derive from the same sector.2 Often this implies that sustained and environmentally sustainable growth is possible only after making special assumptions. Smulders and Gradus [36] assume a unitary elasticity of substitution between pollution and physical capital in production and that abatement expenditures are relatively more effective in reducing pollution than increases in pollution from growth.3 Similarly, Huang and Cai [23] assume the presence of government spending externalities on pollution control, and Schou [34] posits human capital externalities as sources of sustainable growth. Stokey [38] proposes exogenous technical change as the reason for sustained and environmentally sustainable growth. Aghion and Howitt [1] show that sustainable growth is possible without exogenous technical change, or exogenously imposed externalities. However, they remain concerned with the assumption that the elasticity of marginal utility of consumption has to be greater than one (or that utility is highly concave), which is necessary in both Stokey's and Aghion and Howitt's models to attain sustainable growth.4 This assumption ensures that individuals are willing to make the required sacrifices in consumption needed for sustainability. The fact that we focus on natural resources as a factor of production means that in sharp contrast with their analyses, we neither need optimal environmental policy nor to impose the assumption of a greater than unitary elasticity of the marginal utility as necessary conditions for sustainable development.5 A recent paper by Eliasson and Turnovsky [19] is concerned with sustainable and endogenous growth in a two-sector small open economy with renewable natural resources as a factor of production. Our paper differs from Eliasson and Turnovsky in several respects. Firstly, we do not rely on capital accumulation externalities as they do to induce productivity growth. Productivity in our model grows due to endogenous increases in human or knowledge capital. Secondly, while there is structural change in their model, it is limited to changes in the composition of the value of output. There is no structural change in the composition of inputs employed. More importantly, structural change in their model is the result of the assumption that productivity grows only in the non-resource industry (due to the presence of an externality) while any productivity growth in the resource sector is a priori ruled out. In contrast, in our model structural change is an endogenous response brought about due to an unbalanced growth in assets and labor market interactions despite that labor-augmenting technical change takes place at the same rate in both the resource and non-resource sectors. McAusland [30] also relies on learning-by-doing externalities to generate economic growth in a model with two factors of production. Further, she focuses exclusively on the case of open access, and then studies the possibility of sustainable growth in both a closed and open economy. In contrast, we consider the open economy case, but study sustainable growth under well-defined property rights, and under ill-defined property rights or open access. The present paper is also related to the literature explaining structural change. In this literature structural change is the result of non-homothetic preferences [18], [24] and [27] or of imbalanced technical change [4] and [5]. As consumers place a higher value on certain types of goods on becoming wealthier, the economy changes its demand toward non-resource goods. Also, if technical change is sector biased toward the non-resource sector structural change will take place. By contrast, we show that structural change is likely to take place even if preferences are homothetic and technical change is balanced. Given a constraint on the size of the natural asset, a relatively well functioning economy adjusts assets, and subsequently outputs, biasing growth towards the non-resource sector. The paper is organized as follows. Section 2 presents the model, Section 3 defines and characterizes the long-run equilibrium, Section 4 examines the consequences of the absence of an optimal environmental policy, and Section 5 concludes.

We have shown that structural change allows an open economy to grow at a constant rate with environmental sustainability. Endogenous structural change is a response to the presence of a constraint on natural capital which takes place even if consumer preferences are homothetic and if technological progress does not discriminate against the primary or dirty sector. In the long run growth equilibrium the primary sector remains stagnant while the non-resource using sector grows continuously by attracting an increasing volume of increasingly productive labor from the primary sector. Property rights on the natural resource (or optimal environmental policy) are neither necessary nor sufficient for environmentally sustainable economic growth. The rate of growth of the economy over the long run is not affected by environmental policy and the feasibility of environmental sustainability with positive long-run growth is not hampered by incomplete property rights. Optimal environmental policy induces a higher equilibrium stock level of natural resources vis-à-vis the open access case. The rate of economic growth is thus not affected by the (equilibrium) level of resource endowment. Resource-rich and resource-poor economies can grow at similar rates over the long run as long as their non-environmental policies are identical and their non-resource sectors are similar. Moreover, a resource-poor economy (say, an economy that has imperfect resource property rights) can grow faster than a resource-rich economy (say, an economy that has perfect property rights) if the latter has more appropriate non-environmental policies. The real determinant of the feasibility and speed of sustainable growth is the development of a sufficiently productive clean sector that can successfully compete with the primary sector for factors of production, and a sufficiently rapid pace of accumulation of knowledge that enables labor-augmenting productivity and structural change. Market failures that affect, for example, the ability of the economy to invest in knowledge, may frustrate in the long-run structural change and ultimately the capacity of the economy to achieve both positive growth and environmental sustainability.