How much CO2 is produced in a city of almost 100.000 inhabitants? The answer: it depends. Cities are different. 70% of Iserlohns size is used for forestry and agriculture. The city is home to energy-intensive businesses in the areas of metal processing, pharmaceutics or international waste disposal. The Gaia-Institute collected data about the local conditions. How is electricity being produced? What is the heat requirement for buildings? What is the car density? All these aspects affect the carbon footprint. The conclusion: Iserlohn is a positive example of how to reduce CO2 emissions.