Radiokohlenstoff und Tracer für fossiles CO2 Research Topics
Research Topics
Long-term observations of 14CO2 in the global atmosphere
Radiocarbon (14C) is a natural radioactive isotope of carbon produced in the atmosphere by the reaction of cosmic rays with atmospheric nitrogen. The radioactive half-life of 14C is 5700 years, and its abundance is measured as the ratio of 14C to C atoms. In an undisturbed Earth system, atmospheric 14CO2 activity corresponds to an equilibrium between the production of 14CO2 in the atmosphere and its decay in all carbon reservoirs that exchange CO2 with the atmosphere. However, this natural balance between 14CO2 and CO2 (reference level) has been disturbed by human activities over the last century. On the one hand by the continuous release of 14C-free CO2 from the combustion of fossil fuels, known as the Suess effect, and on the other hand by above-ground nuclear weapons tests in the 1950s and early 1960s (14C bomb effect). After the partial nuclear test ban treaty of 1963 came into force, 14CO2 peaked in the northern hemisphere. The subsequent decline in the 14C/C ratio is the result of carbon exchange between the atmosphere, ocean and biosphere. Today, the decline of the 14C/C ratio in CO2 is dominated by the ongoing input of 14C-free CO2 from the combustion of fossil fuels.
Long-term observations of 14CO2 in the regional and urban atmosphere
Carbon dioxide (CO2), which is released during the combustion of fossil fuels, does not contain radiocarbon. At a monitoring station located near fossil fuel emissions, the atmospheric 14C/C ratio in CO2 is therefore diluted by 14C-free fossil CO2 emissions. Comparing the 14C/C ratio at a contaminated station such as the ICOS pilot station Heidelberg with that in clean air, e.g. at Jungfraujoch, one can estimate the locally added CO2 concentration from fossil fuels at the contaminated station (red histogram). Note that in Heidelberg about half of the local CO2 concentration is of biogenic (non-fossil) origin compared to the background air (green histogram).
Current research projects
ICOS Cities (PAUL)
'Pilot Application in Urban Landscapes - Towards integrated city observatories for greenhouse gases' (PAUL) is a four-year H2020 project to support the EUROPEAN GREEN DEAL by creating opportunities to monitor and verify greenhouse gas emissions from densely populated urban areas across Europe.
Our contribution: Feasibility studies and performance of 14CO2 analyses on relaxed eddy accumulation samples. Carrying out the 14CO2 measurements for the urban observations in Paris
CORSO
CO2MVS Research on Supplementary Observations
CORSO will support the establishment of the new CO2MVS (CO2 Monitoring and Verification System) by providing at global and local scales the opportunity to optimise observations of co-emitting species using their emission ratios and uncertainties to better estimate anthropogenic CO2 emissions. Furthermore, the added value of high temporal resolution 14CO2 and APO observations for inversion calculations at global and regional scales will be assessed to better estimate the impact of fossil fuels and biospheric fluxes on atmospheric CO2 concentrations.
Our contribution: Analysis of all air samples collected in 2024 at 11 selected Class 1 ICOS stations and at the Bialystok station in Poland. Compilation and comparison of 14CO2 data from globally distributed background stations.
Completed research projects
VERIFY
VERIFY is developing a system for determining greenhouse gas emissions to support countries' emissions reporting to the Secretariat of the UN Framework Convention on Climate Change. Emissions are estimated on the basis of observations on land, at sea and in the atmosphere.
Our contribution: Testing of alternative tracers (CO, NOx) for fossil CO2
ATTO
Amazon Tall Tower Observatory - Contributions to carbon cycle and climate research
Our contribution: 14CO2- and 222Rn-measurements, development of a radon soil flux map for Brazil
traceRadon
Radon-Metrologie für die Beobachtung des Klimawandels und den Strahlenschutz
Our contribution in co-operation with other project members: Comparison of the Heidelberg radon monitor with other atmospheric radon monitors, improvement of a radon soil flux map for Europe