Global carbon dioxide (CO₂) evasion from inland waters (rivers, lakes, and reservoirs) and carbon (C) export from land to oceans are significant components of the global carbon budget. However, the magnitudes, spatiotemporal patterns, and mechanisms underlying these fluxes remain poorly constrained. In this study, we utilized a coupled terrestrial–aquatic model to evaluate the impacts of climate change, land use, atmospheric CO₂ concentration, nitrogen (N) deposition, and nitrogen fertilizer and manure applications on global CO₂ evasion and riverine C export along the terrestrial-aquatic continuum over the past two centuries.

Our estimates for the preindustrial period (1800s) indicate terrestrial C loadings, riverine C export, and CO₂ evasion were 1,820 ± 507, 765 ± 132, and 841 ± 190 Tg C yr⁻¹, respectively. From 1800 to 2019, multifactorial global changes led to a 25% increase (461 Tg C yr⁻¹) in terrestrial C loadings, reaching 2,281 Tg C yr⁻¹ in the 2010s. Of this increase, 23% (104 Tg C yr⁻¹) was exported to the ocean, while 59% (273 Tg C yr⁻¹) was emitted to the atmosphere. Our findings highlight a dramatic shift in the global C cycle over the past two centuries due to human activities. We estimate that approximately 2.3 Pg C yr⁻¹ entered inland water ecosystems in the 2010s. A major portion of this C loading was emitted as CO₂ (1.1 Pg C yr⁻¹) and exported to the oceans via rivers (0.9 Pg C yr⁻¹). Our results demonstrate that global inland waters recycle and export nearly half of the net land C sink to the atmosphere and oceans, underscoring their critical role in the global C balance. This significant flux should be incorporated into future carbon budget assessments. Enhanced observations in headwater zones and Arctic regions, along with improved process-based models, are needed to refine estimates of inland water C fluxes.