Shoreline Migration, Sediment Accumulation, and Blue Carbon Storage

Satellite image of the Ganges River Delta.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors.

Source: AGU Advances

Coastal river deltas are important components of the global carbon cycle, providing significant long-term net carbon sinks. Silvestre et al. [2026] describe an experimental framework that links shoreline migration to preserved organic material in the subsurface coastal marsh. The experimental results provide insights into how natural, self-driven (autogenic) shifts in a coastline create, move, and bury organic-rich, carbon-storing sediments (termed paleo-blue carbon) over time. The control of shoreline migration by autogenic processes results in larger areal subsurface extent of paleo-blue carbon relative to surface wetland area and enhance carbon burial rates. The author’s results allow rates of organic matter accumulation to be constrained, affecting estimates of the relative size of carbon reservoirs in coastal wetlands.

Diagram of the change in shoreline at times T1 (solid line, green shading) and T2 (dashed line, aqua shading) that occurs on a delta experiencing autogenic transgression, rate of sea level rise landward exceeds the rate of sediment input. The wetland accretion zone (Bw) extend downstream of the shoreline, which increases the longitudinal distance where organic-rich, non-riverine sediment is preserved (black colored seams in subsurface). Credit: Silvestre et al. [2026], Figure 1a

Citation: Silvestre, J. R., Sanks, K. M., Zapp, S. M., Hou, Y., Shaw, J. B., Mukherjee, U., et al. (2026). Autogenic shoreline migration and its effect on the storage of carbon in marginal marine successions. AGU Advances, 7, e2025AV002067. https://doi.org/10.1029/2025AV002067

—Eileen Hofmann, Editor, AGU Advances