This thesis consists of five papers dealing with fairly heterogeneous issues, based on the problems or topics analyzed, but also based on the methodologies used to approach them. The overriding motives are the design of environmental policies in the context of a typical developing country (where Costa Rica is used as a representative of such countries), and the study and application of techniques that can provide the necessary information for policy-making.

We explore the possibilities of using incentive-based environmental regulations of CO2 emissions from international civil aviation. In theory incentive-based instruments such as an emission charge or a tradable emission permit system are better regulations than so-called command-and-control regulations such as emission limits or technology standards.

Over the last two decades many airline markets have been deregulated, resulting in increased competition and use of different types of networks. At the same time there has been an intense discussion on environmental taxation of airline traffic. It is likely that an optimal environmental tax and the effects of a tax differ between different types of aviation markets.

In this paper we analyse the possibility of an incentive-based (IB) environmental regulation of domestic civil aviation in Sweden.