Tourism and the nitrogen cycle: contribution to emissions, deposition and impacts

Tourism is a large and growing phenomenon and economic sector. The main environmental impacts of tourism are related to transport, as is illustrated by tourism's estimated 5% contribution to global carbon dioxide emissions in 2005. Transport is also a major source of nitrogen oxides (NOx) that contribute to air pollution, especially due to the formation of ozone, and to nitrogen deposition. Disruption of the nitrogen cycle has been identified as one of the key issues of global environmental change. Furthermore, transport contributes significantly to the emission of nitrous oxides (N2O), being an important greenhouse gas. Not much is known about tourism's contribution to global NOx and N2O emissions. Even less is known about the spatial distribution of tourism-related emissions of NOx and the ensuing deposition and environmental impacts. This regional focus is crucial as tourism emissions are characterized by strong spatial concentration, thus causing hot spots of NOx emissions and deposition with related environmental effects.

This thesis aims to provide spatially explicit estimates for tourism-related global NOx and N2O emissions, and explore the current and potential future contribution of tourism-related NOx emissions to regional nitrogen deposition and its potential regional environmental impact.