Stefan has extensively worked with sustainable tourism in the Western Indian Ocean (fieldwork in Mauritius, Seychelles, Zanzibar, Madagascar, Sri Lanka) as well as in Jordan. He has also worked with sustainable transports (mostly aviation), renewable energy, carbon offsets & Kyoto, as well as tourism and climate change. His research interests include tourism and climate change, tourism and development, mobility studies, renewable energy, low-carbon tourism, as well as climate policy and carbon trading.