Inverse modeling of carbonyl sulfide to constrain photosynthesis across scales

This research explored whether carbonyl sulfide (COS), a trace gas, can be used to better understand plant photosynthesis. By combining experiments, modeling, inverse modeling, and analyses across scales from leaf to globe, we confirmed that COS leaf uptake is useful for estimating CO2 uptake through photosynthesis. However, COS leaf uptake does not always follow CO2 in a simple way, especially under high temperatures and during stomatal closure, which makes it challenging to use COS as a direct global indicator of carbon uptake. Current limitations come from gaps in observations, incomplete knowledge of plant processes, and constraints in existing models. Overall, this work highlights the potential of COS as a complementary tool, while emphasizing the need for further research and improved data to make it reliable at larger scales.