Spatially explicit modeling of global tidal marsh accumulated carbon storage revealed its heterogeneous evolutionary patterns across world regions during 2001-2020.

Tidal marsh ecosystems play a critical role in mitigating global climate change and achieving carbon-neutral targets. Yet, intensifying anthropogenic activities have led to significant losses in tidal marsh areas, which have substantially undermined their carbon sequestration potential. To comprehensively assess the carbon sequestration capacity of tidal marsh ecosystems and inform effective protection and restoration strategies, this study conducted spatially explicit modeling of global tidal marsh accumulated carbon storage at a 1 km resolution from 2001 to 2020 and analyzed their spatiotemporal evolutionary patterns at both global and regional scales. Results indicated that: (1) Global tidal marsh accumulated carbon storage increased from 2.89 Pg to 5.87 Pg between 2001 and 2020, with the United States, Canada, and Russia collectively accounting for 74% of the total; (2) Hotspot analysis revealed a spatial polarization of accumulated carbon storage; (3) Tidal marsh carbon accumulation rates showed substantial heterogeneity across climate zones, averaging 15.8 t C ha yr globally, with CAR in tropical regions significantly exceeding those in temperate and boreal zones. These findings and the 1-km accumulated carbon storage dataset developed in this study provide valuable insights for identifying ecologically vulnerable regions worldwide and evaluating the effectiveness of tidal marsh restoration initiatives, which are supportive of promoting the sustainable management of tidal marsh ecosystems.