My research has been centered around biosphere–atmosphere exchange in terrestrial ecosystems. The first 10 years mainly dealt with spread and deposition of heavy metals from industrial activities such as power plants, steel works and mining (Greenland), including environmental assessments. The next 10 years were centered on aspects of acid rain and atmospheric chemistry. During this phase I started working with micro-meteorology and implemented flux measurement methods of nitrogen oxides and ozone. During the later years, the main emphasis has been on greenhouse gas exchange including long-term measurements of CO2 fluxes and effects of climate change. My main contribution to the international research community is long-term flux measurements of CO2 over different ecosystems. The data and results have been made available to the international research community through the NASA-funded organisation FLUXNET.