Climate change impacts on soil organic carbon stocks of Mediterranean agricultural areas: A case study in Northern Egypt

- The impact of global change on soil organic C in Egypt was predicted with CarboSOIL.
- Predictions were obtained for soils under different land uses in 2030, 2050 and 2100.
- The intensity of impacts depends largely on land use types.
- Increased soil organic C content was predicted in depth.
- Agricultural irrigated soils are especially sensitive to organic C losses.

Mediterranean agricultural areas are characterised by low soil organic C (SOC) contents and as a consequence they are often degraded and highly vulnerable to environmental changes. Climate change is expected to have a large impact upon these areas but they may be key for mitigation of its effects given their potential for soil C sequestration. Several approaches have been proposed to evaluate climate change impacts on SOC stocks, being soil C models amongst the most effective tools to assess C stocks, dynamics and distribution and to predict trends under climate change scenarios. In this study, we applied the CarboSOIL model and global climate models to predict and analyse the effects of short- (2030), medium- (2050) and long-term (2100) climate changes on SOC contents at standard soil depths (0-25, 25-50 and 50-75 cm) in a Mediterranean arid area (El Fayoum, Northern Egypt) for different land use types. The validation of CarboSOIL with field data proved the consistency of the model. Overall decreases of SOC contents in the topsoil soil layer and increases in the subsoil layers are expected in the short, medium and long term. However, intensity of these changes will depend on the land use type and our results suggest that agricultural land uses relying on irrigation will be particularly vulnerable to losses of SOC stocks. This study demonstrates the importance of assessing SOC contents and dynamics along the soil profile and the potential for soil C sequestration particularly in the subsoil. The methods used in this research can be applied in other Mediterranean areas with available information on soil, land use and climate.