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It is increasingly evident that the direction of technological change responds to economic incentives. We review the literature on directed technical change in the context of environmental economics and labor economics, and we show that these fields have much in common both theoretically and empirically. We emphasize the importance of a balanced growth path and show that the lack of such a path is closely related to the slow development of green technologies in environmental economics and to growing inequality in labor economics. We discuss whether the direction of innovation is efficient.

Do contractual frictions matter when firms are engaged in repeated interactions? This paper argues that long-term relationships, which allow firms to (partly) overcome the static costs associated with low contractibility, will under certain circumstances create dynamic inefficiencies. We consider the repeated interaction between final good producers and intermediate input suppliers, where the provision of the intermediate input is noncontractible. A producer/supplier pair can be a good match or a bad match, with bad matches featuring lower productivity. This allows us to build a cooperative equilibrium where producers can switch suppliers and start cooperation immediately with new suppliers. Every period, one supplier has the opportunity to innovate, and in the baseline model, innovations are imitated after one period. We show that (i) innovations need to be larger to break up existing relationships in the cooperative equilibrium than in either a set-up where the input is contractible or when we preclude cooperation in long-term relationships, (ii) the rate of innovation in the cooperative equilibrium is lower than in the contractible case, and may even be lower than in the non-cooperative equilibrium and (iii) cooperation may reduce welfare. Next, we assume that the frontier technology diffuses slowly to suppliers (instead of after one period). In that case, for sufficiently slow diffusion, the innovation rate in the cooperative equilibrium may be higher than even in the contractible case. Finally, we show that cooperation may also increase relationship specific innovations.

Do higher wages lead to more automation innovation? To answer this question, we first introduce a new measure of automation by using the frequency of certain keywords in patent text to identify automation innovations in machinery. We validate our measure by showing that it is correlated with a reduction in routine tasks in a cross-sectoral analysis in the US. Then we build a firm-level panel dataset on automation patents. We combine macroeconomic data from 41 countries and information on geographical patent history to build firm-specific measures of low-skill and high-skill wages. We find that an increase in low-skill wages leads to more automation innovation with an elasticity between 2 and 4. An increase in high-skill wages tends to reduce automation innovation. Placebo regressions show that the effect is specific to automation innovations. Finally, we use the Hartz labor market reforms in Germany for an event study and find that they are associated with a relative reduction in automation innovations.

International audience; In this paper we use cross-state panel data to show a positive and significant correlation between various measures of innovativeness and top income inequality in the United States over the past decades. Two distinct instrumentation strategies suggest that this correlation (partly) reflects a causality from innovativeness to top income inequality, and the effect is significant: for example, when measured by the number of patent per capita, innovativeness accounts on average across US states for around 17% of the total increase in the top 1% income share between 1975 and 2010. Yet, innovation does not appear to increase other measures of inequality which do not focus on top incomes. Next, we show that the positive effects of innovation on the top 1% income share are dampened in states with higher lobbying intensity. Finally, from cross-section regressions performed at the commuting zone (CZ) level, we find that: (i) innovativeness is positively correlated with upward social mobility; (ii) the positive correlation between innovativeness and social mobility, is driven mainly by entrant innovators and less so by incumbent innovators, and it is dampened in states with higher lobbying intensity. Overall, our findings vindicate the Schumpeterian view whereby the rise in top income shares is partly related to innovation-led growth, where innovation itself fosters social mobility at the top through creative destruction.

This paper builds a two-country, two-sector (polluting, nonpolluting) trade model with directed technical change, examining whether unilateral environmental policies can ensure sustainable growth. The emission rate of the polluting sector depends on its relative use of a clean and a dirty input. A unilateral policy combining clean research subsidies and a trade tax can ensure sustainable growth, while unilateral carbon taxes alone increase innovation in the polluting sector abroad and generally cannot ensure sustainable growth. Relative to autarky and exogenous technical change respectively, trade and directed technical change accelerate environmental degradation either under laissez-faire or with unilateral carbon taxes, yet both help reduce environmental degradation under the appropriate unilateral policy. I characterize the optimal unilateral policy analytically and numerically using calibrated simulations. Knowledge spillovers have the potential to reduce the otherwise large welfare costs of restricting policy to onecountry.

This paper develops a dynamic Heckscher Ohlin Samuelson model with sector-specific human capital and overlapping generations to characterize the dynamics and welfare implications of gradual labor market adjustment to trade. Our model is tractable enough to yield sharp analytic results, that complement and clarify an emerging empirical literature on labor market adjustment to trade. Existing generations that have accumulated specific human capital in one sector can switch sectors when the economy is hit by a trade shock. Nonetheless, the shock induces few workers to switch, generating a protracted adjustment that operates largely through the entry of new generations. This results in wages being tied to the sector of employment in the short-run but to the skill type in the long-run. Relative to a world with general human capital, welfare is improved for the skill group whose type-intensive sector shrinks. We extend the model to include physical capital and show that the transition is longer when capital is mobile. We also introduce nonpecuniary sector preferences and show that larger gross flows are associated with a longer transition.

A key question in the economics of climate change is the importance of global policy coordination in reducing carbon emissions. In this paper, we study this question using a two-country (North–South) extension of Acemoglu et al. (2012) which introduces directed technical change into a general equilibrium model of climate change. We find that, first, the optimal policy necessarily requires global policy coordination, with the implementation of research subsidies and carbon taxes in both North and South. Second, under certain circumstances, appropriately chosen environmental regulations in the North alone can prevent the worst environmental disasters. In particular, such disasters can be prevented by a combination of carbon taxes and clean research subsidies under the restrictive conditions that (a) the two inputs are substitutable in both countries; (b) there is no international trade between the North and the South; and (c) the South imitates technologies invented in the North. Third, international trade between the North and the South typically makes it more difficult to prevent environmental disasters through unilateral policies in the North, because environmental regulation in the North may induce full specialization by the South in dirty input production, as imitation of clean technologies by the South then ceases to be profitable. Hence, given current circumstances, global policy coordination is highly desirable.

International audience; Can directed technical change be used to combat climate change? We construct new firm-level panel data on auto industry innovation distinguishing between “dirty” (internal combustion engine) and “clean” (e.g., electric, hybrid, and hydrogen) patents across 80 countries over several decades. We show that firms tend to innovate more in clean (and less in dirty) technologies when they face higher tax-inclusive fuel prices. Furthermore, there is path dependence in the type of innovation (clean/dirty) both from aggregate spillovers and from the firm’s own innovation history. We simulate the increases in carbon taxes needed to allow clean technologies to overtake dirty technologies.

This paper develops a dynamic Heckscher Ohlin Samuelson model with sector-specific human capital and overlapping generations to characterize the dynamics and welfare implications of gradual labor market adjustment to trade. Our model is tractable enough to yield sharp analytic results, that complement and clarify an emerging empirical literature on labor market adjustment to trade. Existing generations that have accumulated specific human capital in one sector can switch sectors when the economy is hit by a trade shock. Nonetheless, the shock induces few workers to switch, generating a protracted adjustment that operates largely through the entry of new generations. This results in wages being tied to the sector of employment in the short-run but to the skill type in the long-run. Relative to a world with general human capital, welfare is improved for the skill group whose type-intensive sector shrinks. We extend the model to include physical capital and show that the transition is longer when capital is mobile. We also introduce nonpecuniary sector preferences and show that larger gross flows are associated with a longer transition.

In this paper we use cross-state panel data to show that top income inequality is (at least partly) driven by innovation. We first establish a positive and significant correlation between various measures of innovativeness and top income inequality in cross-state panel regressions. Two distinct instrumentation strategies suggest that this correlation (partly) reflects a causality from innovativeness to top income inequality, and the effect is significant: for example, when measured by the number of patent per capita, innovativeness accounts on average across US states for around 17% of the total increase in the top 1% income share between 1975 and 2010. Finally, we show that innovation does not increase broader measures of inequality which do not focus on top incomes, and that innovation is positively correlated with social mobility, but less so in states with more intense lobbying activities.

What are the effects of cyclical fiscal policy on industry growth? We show that industries with a relatively heavier reliance on external finance or lower asset tangibility tend to grow faster (in terms of both value added and of labor productivity growth) in countries that implement fiscal policies that are more countercyclical. We reach this conclusion using Rajan and Zingales׳s (1998) difference-in-difference methodology on a panel data sample of manufacturing industries across 15 OECD countries over the period 1980–2005.

This paper builds a two-country (North, South), two-sector (polluting, nonpolluting) trade model with directed technical change, examining whether unilateral environmental policies can ensure sustainable growth. The polluting good is produced with a clean and a dirty input. I show that a temporary Northern policy combining clean research subsidies and a trade tax can ensure sustainable growth but Northern carbon taxes alone cannot. Trade and directed technical change accelerate environmental degradation either under laissez-faire or if the North implements carbon taxes, yet both help reduce environmental degradation under the appropriate unilateral policy. I characterize the optimal unilateral policy analytically and numerically using calibrated simulations.

Persistently increasing wage inequality, polarization of the wage distribution, and stagnating real wages for low skill workers are some of the most salient features of modern labor markets, but are di fficult to reconcile with the theoretical literature on economic growth. To better understand the mechanisms driving these phenomena, we construct an endogenous growth model of directed technical change with automation (the introduction of machines which replace low-skill labor and complement high-skill labor) and horizontal innovation (the introduction of new products, which increases demand for both types of labor). The economy endogenously follows three phases: First, both low-skill wages and automation are low, while income inequality and the labor share are constant. Second, increases in low-skill wages stimulate investment in automation, which depresses the growth rate of future low-skill wages (potentially to negative), and reduces the total labor share. Finally, the share of automated products stabilizes and low-skill wages grow at a positive but lower rate than high-skill wages. Adding middle skill workers allows the model to generate a phase of wage polarization after one of uniform increase in income inequality. We show that this framework can quantitatively account for the evolution of the skill premium, the skill ratio and the labor share in the US since the 1960s.

Can directed technical change be used to combat climate change? We construct new firm-level panel data on auto industry innovation distinguishing between 'dirty' (internal combustion engine) and 'clean' (e.g. electric and hybrid) patents across 80 countries over several decades. We show that firms tend to innovate relatively more in clean technologies when they face higher tax-inclusive fuel prices. Furthermore, there is path dependence in the type of innovation both from aggregate spillovers and from the firm's own innovation history. Using our model we simulate the increases in carbon taxes needed to allow clean to overtake dirty technologies.

This paper introduces endogenous and directed technical change in a growth model with environmental constraints. A unique final good is produced by combining inputs from two sectors. One of these sectors uses “dirty” machines and thus creates environmental degradation. Research can be directed to improving the technology of machines in either sector. We characterize dynamic tax policies that achieve sustainable growth or maximize intertemporal welfare. We show that: (i) in the case where the inputs are sufficiently substitutable, sustainable long-run growth can be achieved with temporary taxation of dirty innovation and production; (ii) optimal policy involves both “carbon taxes” and research subsidies, so that excessive use of carbon taxes is avoided; (iii) delay in intervention is costly: the sooner and the stronger is the policy response, the shorter is the slow growth transition phase; (iv) the use of an exhaustible resource in dirty input production helps the switch to clean innovation under laissez-faire when the two inputs are substitutes. Under reasonable parameter values and with sufficient substitutability between inputs, it is optimal to redirect technical change towards clean technologies immediately and optimal environmental regulation need not reduce long-run growth., Toulouse Network for Information Technology, Canadian Institute for Advanced Research, Bruegel

This paper introduces endogenous and directed technical change in a growth model with environmental constraints and limited resources. A unique final good is produced by combining inputs from two sectors. One of these sectors uses "dirty" machines and thus creates environmental degradation. Research can be directed to improving the technology of machines in either sector. We characterize dynamic tax policies that achieve sustainable growth or maximize intertemporal welfare, as a function of the degree of substitutability between clean and dirty inputs, environmental and resource stocks, and cross-country technological spillovers. We show that: (i) in the case where the inputs are sufficiently substitutable, sustainable long-run growth can be achieved with temporary taxation of dirty innovation and production; (ii) optimal policy involves both "carbon taxes" and research subsidies, so that excessive use of carbon taxes is avoided; (iii) delay in intervention is costly: the sooner and the stronger is the policy response, the shorter is the slow growth transition phase; (iv) the use of an exhaustible resource in dirty input production helps the switch to clean innovation under laissez-faire when the two inputs are substitutes. Under reasonable parameter values (corresponding to those used in existing models with exogenous technology) and with sufficient substitutability between inputs, it is optimal to redirect technical change towards clean technologies immediately and optimal environmental regulation need not reduce long-run growth. We also show that in a two-country extension, even though optimal environmental policy involves global policy coordination, when the two inputs are sufficiently substitutable environmental regulation only in the North may be sufficient to avoid a global disaster.

This paper evaluates whether the cyclical pattern of fiscal policy can affect growth. We first build a simple endogenous growth model where entrepreneurs can invest either in short-run projects or in long-term growth enhancing projects. Long-term projects involve a liquidity risk which credit constrained firms try to overcome by borrowing on the basis of their short-run profits. By increasing firms' market size in recessions, a countercyclical fiscal policy will boost investment in productivity-enhancing long-term projects, and the more so in sectors that rely more on external financing or which display lower asset tangibility. Second, the paper tests this prediction using Rajan and Zingales (1998)'s diff-and-diff methodology on a panel data sample of manufacturing industries across 17 OECD countries over the period 1980-2005. The evidence confirms that the positive effects of a more countercyclical fiscal policy on value added growth, productivity growth, and R&D expenditure, are indeed larger in industries with heavier reliance on external finance or lower asset tangibility.