The Science

Current climate models disagree on how much carbon dioxide (CO₂) land ecosystems take up for photosynthesis. In response, atmospheric scientists, biogeochemists, and oceanographers have proposed measuring a gas called carbonyl sulfide (COS) to help quantify the contribution that photosynthesis makes to carbon uptake.

The Impact

Photosynthesis is a key climate forcing process in the terrestrial biosphere. It removes CO₂ from the atmosphere and stores carbon in plants, slowing the rate of climate change. Measurements of atmospheric COS provide the first global-scale estimates of this carbon-climate feedback.

Summary

Ten years ago, scientists discovered a massive and persistent biosphere signal in atmospheric COS measurements. In these data, COS and CO₂ levels follow a similar seasonal pattern, but the COS signal is much stronger over continental regions, suggesting that the terrestrial biosphere is a sink for COS. The remarkable discovery led scientists to wonder: Could COS be used as a tracer for carbon uptake? An explosive growth in COS studies followed as scientists attempted to answer this question, including a COS record from the present to the Last Glacial Maximum, satellite-based maps of the dynamics of COS in the global atmosphere, and measurements of ecosystem fluxes of COS.

Principal Investigator

J. Elliott Campbell
University of California, Santa Cruz
elliott.campbell@ucsc.edu

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
daniel.stover@science.doe.gov

Funding

Terrestrial Ecosystem Science program of the Office of Biological and Environmental Research, within the U.S. Department of Energy Office of Science, under Contract No. DE-SC0011999.

References