Stronger sensitivity of plant photosynthesis to rising CO₂ in high elevation ecosystems

The CO₂ fertilization effect (CFE) is often regarded as a key driver of the increasing terrestrial carbon sink over recent decades. However, its spatial pattern remains highly uncertain, with limited empirical and model-based studies addressing its elevational patterns. This uncertainty significantly affects projections of future terrestrial carbon dynamics and challenges the potential role of land ecosystems as nature-based climate solutions.Theoretically, CFE is expected to increase with elevation due to the heightened sensitivity of carboxylation under reduced CO₂ partial pressure. To our knowledge, this study is the first empirical effort to investigate the elevational response of CFE. Our findings help address a major uncertainty in climate-carbon feedback studies