Arctic tundra ecosystems have been major carbon sinks throughout the Holocene. However, during the past decades high latitude environments have been observed to warm faster and to a greater extend than lower latitudes. It remains unclear whether this warming trend will cause tundra ecosystems to become a net carbon source or whether changes in the ecosystems, such as adaptation of microbial and plant communities and increased biomass production, will offset possible increased carbon emissions. In order to investigate and address this uncertainty, landscape scale measurements of carbon exchange are necessary in different arctic ecosystems.