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.
Aviation and climate change
We describe the current status of knowledge regarding the contribution of aviation to anthropogenic climate forcing. The emissions and associated radiative forcings from aviation are compared to those from other modes of transport. The different analytical metrics used to quantify climate forcing are presented showing their relevancies and uncertainties. The discussion then focuses on the use of radiative forcing, one of the most commonly used metric, in accounting for the climate change contribution from aviation with a particular look at how the contribution from CO2 and non-CO2 greenhouse gases can be compared.
Sources and chemistry of NOx in the upper troposphere over the United States
The origin of NOx in the upper troposphere over the central United States is examined using aircraft observations obtained during the SUCCESS campaign in April–May of 1996. Correlations between NOy (sum of NOx and its oxidation products) and CO at 8–12 km altitude indicate that NOx originates primarily from convective transport of polluted boundary layer air. Lightning and aircraft emissions appear to be only minor sources of NOx. Chemical steady state model calculations constrained by local observations of NO underestimate the measured NOx/NOy concentration ratio at 8–12 km altitude by a factor of two on average. The magnitude of the underestimate is correlated with concentrations of condensation nuclei, which we take as a proxy for the age of air in the upper troposphere. We conclude that the NOx/NOy ratio is maintained above chemical steady state by frequent convective injections of fresh NOx from the polluted boundary layer and by the long lifetime of NOx in the upper troposphere (5–10 days). In contrast to previous studies, we find no evidence for fast heterogeneous recycling from HNO3 to NOx in the upper troposphere.