Over the last few years, significant advances have been made in both in situ and remote sensing technologies for measuring greenhouse gases (GHGs). The successful launch of global observing systems such as the Orbiting Carbon Observatory (OCO-2), the Soil Moisture Active Passive (SMAP) missions as well as deployment of localized surface networks and aircraft campaigns such as the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) and the Megacities Carbon Project, is starting to yield more information on natural and anthropogenic sources than ever before. While these multiple observational platforms provide a significant potential for the monitoring of GHG emissions, more and more uncertainties are coming to light regarding our understanding of the global and regional budgets of GHGs, errors due to deficiency in atmospheric transport modeling (especially related to convection and vertical mixing), and identification and quantification of climate feedback sensitivities. This session solicits abstracts that address these uncertainties using models and observations and provide new insights on understanding GHG dynamics at various spatial (local to global) and temporal (sub-diurnal to decadal) scales. We encourage contributions on current and prospective observation technologies for GHGs, modeling studies to quantify budgets and/or uncertainties in GHG flux estimates, and evaluation and benchmarking of GHG estimates from Earth System Models using contemporary observations. We also encourage studies of perturbations to the carbon balance of terrestrial ecosystems in response to climate variability and change, especially as they combine models and observations or pertain to carbon-climate feedback. In addition, we seek contributions on improved quantification and understanding of underlying GHG emissions at the urban scale, policy issues related to GHG monitoring and regulation, and how the current state of the science is informing policy decisions.