A recent literature, dealing with special markets characterized by bilateral network externalities, is summarized and critically assessed. Specific features of these markets, in terms of pricing principles and externalities, are discussed first. Afterwards, several issues related to competition between platforms are considered. Finally, implications for competition policy and prospects for future research are briefly discussed.

Human-generated greenhouse gases depend on the level and emissions intensity of economic activities. Therefore, most climate-change studies are based on the models and scenarios of economic growth. Economic growth itself, however, is likely to be affected by climate-change impacts. These impacts affect the economy in multiple and complex ways: changes in productivity, resource endowments, production and consumption patterns. We use a new dynamic, multi-regional computable general equilibrium (CGE) model of the world economy to answer the following questions: Will climate-change impacts significantly affect growth and wealth distribution in the world? Should forecasts of human-induced greenhouse gas emissions be revised, once the climate-change impacts are taken into account? We found that, even though economic growth and emission paths do not change significantly at the global level, relevant differences exist at the regional and sectoral level. In particular, developing countries appear to suffer the most from the climate-change impacts.