Long-Term Land Use/Land Cover Change and Climate-Driven Projection of Soil Organic Carbon Stocks and Sequestration Using the RothC Model in the Northern Nile Delta, Egypt

Soil organic carbon (SOC) is a major component of the global carbon cycle. This study aimed to: (i) monitor five decades’ land use/land cover (LULC) changes in the northern Nile delta using Landsat imagery; (ii) quantify baseline SOC stocks (SOCs) in 2021; (iii) project SOCs and potential SOC sequestration (PSOCS) to 2100 under four SSP2-4.5 climate scenarios using RothC model; and (iv) evaluate uncertainty in SOCs and PSOCS projections using the Monte Carlo approach. Sixty soil samples were collected during the winter and summer seasons of 2018/2019 (30 per season). Agricultural land expanded from 12% in 1972 to 35% in 2021, while fish farms, established in the 1990s, accounted for 24% of the area by 2021. SOCs varied across LULC types and seasons. Between 13 and 28% of agricultural land exceeding 7 Mg C ha−1 in summer and winter, respectively. Barren land and sabkha were characterized by low SOCs (<3 Mg C ha−1). Model predictions indicate that mean SOCs will increase from 5.83 (2021) to 6.16 (mid-century), followed by a decline to 5.96 Mg C ha−1 by 2100. Estimated PSOCS range from 0.13 to 0.32 Mg C ha−1. Monte Carlo uncertainty analysis yielded median SOCs between 6.01 and 6.27 Mg C ha−1 and median PSOCS between 0.18 and 0.44 Mg C ha−1, reflecting moderate projection uncertainty.