Many lakes are found at high-latitudes in arctic areas. As they receive and process terrestrial organic carbon, these lakes link terrestrial and aquatic carbon cycles, while emitting CO2 to the atmosphere. Yet, their remote location and long winter periods make studying these systems difficult. This period of ice-cover and subsequent ice-melt is of significant importance for understanding CO2 emission from arctic clear water systems, Dirk Verheijen shows in his thesis at Umeå University, Sweden.