Since coastal wetlands have been severely degraded and polluted by human activities, they have increasingly become a significant source of greenhouse gases (GHGs), so understanding the characteristics of their emissions is critical for devising future climate change mitigation strategies. This study modified a model based on carbon balance to forecast carbon stored and CO₂, CH₄ emissions in four types of typical tidal flats—Phragmites australis (PA), Spartina alterniflora (SA), Suaeda japonica (SJ), and Bare Tidal Flat (BTF) in Korea’s Ganghwa province from 2017 to 2047. The model was built using biomass data from salt plant species collected in different locations. The results indicate that the total annual simulated flow of CH₄ increased over time in all four areas, most notably in SA, while CO₂ remained relatively stable. The mean CO₂ and CH₄ fluxes in the four types of representative tidal flats were in the range of 0.03 to 19.1 mg m⁻² d⁻¹ and 0.007 to 5.23 mg m⁻² d⁻¹, respectively, across all seasons. Besides, the results indicate that the amount of carbon accumulated in the top soil increases linearly over time in nearly all areas studied, ranging from 0.01 to 0.13 (kgC m⁻² yr⁻¹). In general, the study provides a model for Korean tidal flats that incorporates carbon storage and GHG emissions in the intertidal zone in order to develop potential GHG reduction scenarios.