Lead
With the release of the Summary for Policymakers of the IPCC Working Group I on September 27, 2013 the role of carbon dioxide (CO2) as the main actor in climate change is further strengthened. It explicitly states:“Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750.”The task for the research community therefore is to further investigate the biogeochemical cycles, i.e. monitoring the concentrations of relevant greenhouse gases, quantifying their temporal and spatial emissions, improving Earth system models in order to understand the underlying processes and to assess the climate change impacts on natural resources, economy and society. This and the previous projects aimed at establishing the longest CO2 record in Switzerland, namely at Jungfraujoch.

Lay summary

The longest CO2 record in Switzerland has only started in late 2000, since the end of 2004 in a continuous manner. This record was complemented by associated parameters such as (i) continuous O2 measurements and (ii) discrete flask sampling for Ar/N2 and isotope compositions on CO2 and the main air components. The focus of the upcoming project period – besides the common interpretation of the full suite atmospheric measurements – will be on specific (triple) isotope ratio measurements, namely d17O, d18O, and D17O of atmospheric molecular oxygen (O2) and both tropospheric and stratospheric water vapour (H2O). Preliminary measurements done at our laboratory have revealed interesting variations in D17O.

Triple isotopic composition of oxygen allows us to investigate biogeochemical processes as well as gas exchange fluxes between the upper troposphere and lower stratosphere.