The ECJ Judgment on the Extensions of the ETS to Aviation: An Economist's Discontent
Few EU decisions have caused more international outcry than the extension of the EU Emissions Trading System (ETS) to apply to aviation. The directive was legally challenged by US airlines before a UK court, which referred the case to the European Court of Justice (ECJ) for a preliminary ruling concerning the compatibility of the directive with international law. This paper discusses the argumentation by the ECJ and the Advocate General from an economic perspective. Such an analysis is warranted in light of the fact that the contested measure is an economic regulation, the international laws that are invoked have clear economic objectives, and the ECJ judgment and the opinion by the Advocate General at least partly rely on economic concepts and mechanisms. An economic analysis also seems warranted from a legal point of view since the quality of the judgment and of the opinion presumably depend on the soundness of their economic reasoning. It is found that the argumentation by the legal authorities is highly questionable in important parts, when viewed from an economic perspective.
Can border carbon taxes fit into the global trade regime? Bruegel Policy Brief 2013/06, 9 December 2013
One complement to domestic climate policies could be the regulation of carbon dioxide emissions arising during the production of imported products. Such ‘border carbon adjustments’ (BCAs) are said to have several benefits, but are also severely criticised. This Policy Brief highlights some weaknesses in the standard argumentation for BCAs. But there is an alternative argument for border carbon measures, based on the fact that countries expose each other to climate externalities. The reformulated argument is economically more convincing, and provides a more convincing justification for the extraterritorial feature of border carbon measures. However, there are also several important factors mitigating against the implementation of such measures, including the risk that these measures will be used for protectionism. 
 
One complement to domestic climate policies could be the regulation of carbon dioxide emissions arising during the production of imported products. Such ‘border carbon adjustments’ (BCAs) are said to have several benefits, but are also severely criticised. This Policy Brief highlights some weaknesses in the standard argumentation for BCAs. But there is an alternative argument for border carbon measures, based on the fact that countries expose each other to climate externalities. The reformulated argument is economically more convincing, and provides a more convincing justification for the extraterritorial feature of border carbon measures. However, there are also several important factors mitigating against the implementation of such measures, including the risk that these measures will be used for protectionism.
Estimates of the Climate Response to Aircraft CO2 and NOx Emissions Scenarios
A combination of linear response models is used to estimate the transient changes in the global means of carbon dioxide (CO2) concentration, surface temperature, and sea level due to aviation. Apart from CO2, the forcing caused by ozone (O3) changes due to nitrogen oxide (NOx) emissions from aircraft is also considered. The model is applied to aviation using several CO2 emissions scenarios, based on reported fuel consumption in the past and scenarios for the future, and corresponding NOx emissions. Aviation CO2 emissions from the past until 1995 enlarged the atmospheric CO2 concentration by 1.4 ppmv (1.7% of the anthropogenic CO2 increase since 1800). By 1995, the global mean surface temperature had increased by about 0.004 K, and the sea level had risen by 0.045 cm. In one scenario (Fa1), which assumes a threefold increase in aviation fuel consumption until 2050 and an annual increase rate of 1% thereafter until 2100, the model predicts a CO2 concentration change of 13 ppmv by 2100, causing temperature increases of 0.01, 0.025, 0.05 K and sea level increases of 0.1, 0.3, and 0.5 cm in the years 2015, 2050, and 2100, respectively. For other recently published scenarios, the results range from 5 to 17 ppmv for CO2 concentration increase in the year 2050, and 0.02 to 0.05 K for temperature increase. Under the assumption that present-day aircraft-induced O3 changes cause an equilibrium surface warming of 0.05 K, the transient responses amount to 0.03 K in surface temperature for scenario Fa1 in 1995. The radiative forcing due to an aircraft-induced O3 increase causes a larger temperature change than aircraft CO2 forcing. Also, climate reacts more promptly to changes in O3 than to changes in CO2 emissions from aviation. Finally, even under the assumption of a rather small equilibrium temperature change from aircraft-induced O3 (0.01 K for the 1992 NOx emissions), a proposed new combustor technology which reduces specific NOx emissions will cause a smaller temperature change during the next century than the standard technology does, despite a slightly enhanced fuel consumption. Regional effects are not considered here, but may be larger than the global mean responses.