Ingeborg Levin (1953-2024).

Pioneer in radiocarbon and atmospheric research.

Estimating regional fossil fuel CO concentrations from CO observations: challenges and uncertainties.

The direct way to estimate the regional fossil fuel CO surplus (ΔffCO) at a station is by measuring the ΔCO depletion compared with a respective background. However, this approach has several challenges, which are (i) the choice of an appropriate ΔCO background, (ii) potential contaminations through nuclear CO emissions and (iii) masking of ΔffCO by C-enriched biosphere respiration. Here we evaluate these challenges and estimate potential biases and typical uncertainties of C-based ΔffCO estimates in Europe.

Making the case for an International Decade of Radiocarbon.

Radiocarbon (C) is a critical tool for understanding the global carbon cycle. During the Anthropocene, two new processes influenced C in atmospheric, land and ocean carbon reservoirs. First, C-free carbon derived from fossil fuel burning has diluted C, at rates that have accelerated with time.

Verification of greenhouse gas emission reductions: the prospect of atmospheric monitoring in polluted areas.

Independent verification of greenhouse gas emissions reporting is a legal requirement of the Kyoto Protocol, which has not yet been fully accomplished. Here, we show that dedicated long-term atmospheric measurements of greenhouse gases, such as carbon dioxide (CO(2)) and methane (CH(4)), continuously conducted at polluted sites can provide the necessary tool for this undertaking. From our measurements at the semi-polluted Heidelberg site in the upper Rhine Valley, we find that in the catchment area CH(4) emissions decreased on average by 32±6% from the second half of the 1990s until the first half of the 2000s, but the observed long-term trend of emissions is considerably smaller than that previously reported for southwest Germany.

Radiocarbon observations in atmospheric CO2: determining fossil fuel CO2 over Europe using Jungfraujoch observations as background.

Monthly mean 14CO2 observations at two regional stations in Germany (Schauinsland observatory, Black Forest, and Heidelberg, upper Rhine valley) are compared with free tropospheric background measurements at the High Alpine Research Station Jungfraujoch (Swiss Alps) to estimate the regional fossil fuel CO2 surplus at the regional stations. The long-term mean fossil fuel CO2 surplus at Schauinsland is 1.31+/-0.