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The seasonal amplitude of atmospheric CO2 has increased over the past 50 years. This increase is linked to a larger seasonal amplitude of global net biosphere exchange (NBE), driven by changes in atmospheric CO2 concentration, temperate, soil moisture, ecosystem processes, and cropland productivity. A handful of studies report discrepancies between eddy flux or atmospheric observations and the seasonal amplitude of NBE estimated by Dynamic Global Vegetation Models (DGVMs). In this study, by contrast, we use global observations from OCO-2 and in situ sites to evaluate the seasonal amplitude of NBE in an ensemble of DGVMs from the TRENDY model inter-comparison. Specifically, we input the TRENDY model estimates for the years 2015-2018 into GEOS-Chem and compare the resulting atmospheric CO2 estimates against OCO-2 and in situ data. We also compare the TRENDY models against …