A research team led by the Institute of Atmospheric Physics of the Chinese Academy of Sciences (CAS), in collaboration with researchers from Nanjing University, Tsinghua University, and several other CAS institutes, has developed a new model to assess the carbon sequestration capacity of global salt marshes, filling a gap in blue carbon accounting.

Named SAL-GPP, the new model is the first process-based model specifically designed for salt marsh ecosystems. Unlike traditional terrestrial carbon models, which overlook coastal-specific environmental factors, SAL-GPP uniquely incorporates tidal and salinity stress modules to simulate photosynthesis in both C3 and C4 salt marsh plants across different salinity gradients.

The study was recently published in Environmental Science & Technology.

"Salt marshes are among the most efficient blue carbon ecosystems on Earth, storing substantial amounts of carbon despite their limited distribution," said Prof. LI Tingting, corresponding author of the study. "However, previous global carbon assessments have largely overlooked the contributions of coastal wetlands due to limitations in existing models."

The team validated the model using data from multiple flux tower sites worldwide. Results showed strong performance, with a coefficient of determination (R²) of 0.82 for daily productivity simulations—indicating a strong correlation between the model's predictions and actual observations.

Using SAL-GPP, the researchers generated the world's first high-resolution (500-meter) global salt marsh productivity dataset covering the period 2011–2020. Simulations reveal that global salt marshes have an average annual gross primary production of 66.89 ± 11.68 Tg C yr^-1, with hotspots in the southeastern United States, Western Europe, China's southeastern coast, and Australia collectively accounting for nearly 64% of the global total.

Compared to mainstream remote sensing products such as MODIS, GLASS, and GOSIF, as well as 17 TRENDY model simulations, the new dataset demonstrates superior accuracy. It provides crucial scientific support for integrating coastal wetlands into global carbon budgets.

This research was supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China.

Schematic diagram of the SAL-GPP model framework. (Image by ZHOU Zhuoya et al.)