The creation of a common European currency has been scrutinized in the context of optimum currency area theory since its origin in Mundell (1961). The debate gained particular prominence in light of the endogeneity hypothesis (Frankel and Rose 1998), which argues that once two countries establish a common currency, their economic structures and cycles increasingly align due to strengthening intra-industry trade. By contrast, the specialization hypothesis (Eichengreen 1992; Krugman and Venables 1996) argues that the creation of a currency union will predominantly increase inter-industry trade, ultimately lowering business cycle correlation. To test these views, we establish several indices of bilateral trade intensity across EU members using input–output data, measuring gross and so-called value-added trade, which also considers the contribution of intermediary goods in the production of final exports. The results of the fixed effect panel data framework indicate a strong and robust empirical relationship between growth correlations and intra-industry trade, much in line with both Mundell’s and Frankel and Rose’s theories. However, we cannot establish a similarly robust relationship between total trade intensity and growth correlations. We reconcile these results by identifying a statistically significant relationship between economic alignment and trade when only considering industrial production, highlighting the importance of pan-European industrial supply chains for European economic integration. Rerunning our regression framework on the subsample of the eurozone indicates that the common currency area displayed even stronger properties of an optimum currency area than the entire European Union.

The creation of a common European currency has been scrutinized in the context of optimum currency area theory since its origin in Mundell (1961). The debate gained particular prominence in light of the ’endogeneity’ theorem (Frankel and Rose, 1998), which argues that, once two countries establish a common currency, their economic structures and cycles increasingly align due to strengthening intra-industry trade. By contrast, the ’specialization’ theorem (Eichengreen, 1992; Krugman, 2013) argues that the creation of a currency union will predominantly increase inter-industry trade, ultimately lowering business cycle correlation. To test these views, we establish several indices of bilateral trade intensity across EU members using input-output data, measuring gross and so-called ’value-added’ trade, which also considers the contribution of intermediary goods in the production of final exports. The results of the fixed effect panel framework indicate a strong and robust empirical relationship between growth correlations and intra-industry trade, much in line with both Mundell’s and Frankel and Rose’s theories. However, we cannot establish a similarly robust relationship between total trade intensity and growth correlations. We reconcile these results by identifying a statistically significant relationship between economic alignment and trade when only considering industrial production, highlighting the importance of pan-European industrial supply chains for European economic integration. In contrast to the EU-28, the Eurozone does not display properties of an Optimum Currency Area. We partially attribute this to the Eurozone periphery, which shows a high degree of misalignment within itself; excluding the Eurozone periphery from our initial regressions further improves the results.

Which renewable energy (RE) policy instrument is most effective in expanding the international diffusion of RE and what is the role of innovation? We consider rich policy and patent data for 189 countries and territories to investigate these diversely debated questions for wind and solar photovoltaic capacities. This allows us, firstly, to contribute to the limited evidence on the effect of RE innovation on RE diffusion and its interrelated influence with RE support policies. Secondly, we can evaluate the disentangled individual policies' effectiveness in a broad instrument-country context. Thirdly, we control for the inherent endogeneity of policy instruments and innovation. We find that RE innovation, which appears to be largely policy-induced, is among the most promising ways to increase RE capacities. The most effective policy instruments tend to be quotas with certificate trading, tendering, and fiscal instruments that provide specific investment support, i.e. investment tax credits and capital subsidies. Less tangible and projectable measures, such as the most commonly implemented sales-related tax reductions and RE targets, are least effective. While interactions between instruments influence the composition of a well-designed policy mix, there are also differences in the policies' effectiveness and role of innovation depending on the countries' level of development.

Greenhouse gas emission (GHGE) taxes on food products have recently been proposed as means to help reduce agricultural emissions. Numerous authors have calculated potential GHGE reductions in case such a tax was implemented in certain countries or regions. They did however assume a reduced production of GHGE-intense foods equal to the decline in demand induced by the tax. This omits, however, possible increases of net-exports that might offset such a demand reduction. Herein, the market dynamic behind this so-called “emission leakage” is explained and its effect quantified for a greenhouse gas tax in the European Union. We use the European Forest and Agricultural Sector Optimization Model for the quantitative analysis and simulate a greenhouse gas tax on all food products, based on their individual emission levels. The partial equilibrium model covers all world regions and hence the tax's effects on international trade of agricultural commodities can be examined. It was found that 43% of the greenhouse gas reduction indicted by a domestic consumption reduction is lost through emission leakage. This already includes the mitigating effects of a production shift from inefficient to efficient producers that is another consequence of increased exports from the European Union. A greenhouse gas emission tax on food products is hence much less efficient than previously proposed, if it is not introduced globally or trade is not restricted.