Atmospheric carbonyl sulfide sources from anthropogenic activity: Implications for carbon cycle constraints

Carbonyl sulfide (COS) has recently emerged as an atmospheric tracer of gross primary production. All modeling studies of COS air‐monitoring data rely on a climatological anthropogenic inventory that does not reflect present conditions or support interpretation of ice core and firn trends. Here we develop a global anthropogenic inventory for the years 1850 to 2013 based on new emission measurements and material‐specific data. By applying methods from a recent regional inventory to global data, we find that the anthropogenic source is similar in magnitude to the plant sink, confounding carbon cycle applications. However, a material‐specific approach results in a current anthropogenic source that is only one third of plant uptake and is concentrated in Asia, supporting carbon cycle applications of global air‐monitoring data. Furthermore, changes in the anthropogenic source alone cannot explain the century‐scale mixing ratio growth, which suggests that ice and firn data may provide the first global history of gross primary production.