The increasing seasonality of atmospheric CO₂ is strongly linked with enhanced land vegetation activities in the last 5 decades, for which the importance of increasing CO₂, climate and land use/cover change was evaluated in single model studies (Zeng et al., 2014; Forkel et al., 2016). Here we examine the relative importance of these factors in multiple models. Our results highlight models can show similar results in some benchmarks with different underlying regional dynamics.