Evaluating Urban Impacts on Energy, Carbon, and Hydrological Cycles Across Morocco

Abstract

Urbanization is a pervasive form of land-use change that alters surface energy, carbon, and water fluxes. Using the Simple Biosphere 2 (SiB2) land surface model, we quantify the effects of urban land transformation on land surface temperature (LST), gross primary productivity (GPP), and surface water discharge across Morocco. We find that urban effects on LST exhibit strong seasonality as urban areas are consistently warmer than surrounding rural land in winter, whereas summer conditions can produce urban heat sink effects, with rural surfaces becoming warmer than urban centers by up to 0.4 °C as a seasonal mean. We quantify the relationship between urbanization intensity and its local impact on LST, showing that it holds strongly throughout most of the year but weakens in summer, when background regional climate and topography play a greater role. Urbanization was found to reduce ecosystem productivity, with the largest urban induced GPP losses occurring in northern urban settings. Across the Climate Modeling Grid (CMG) cells meeting the study’s inclusion criterion of ≥5% impervious surface area (ISA), three counterfactual pre-urbanization scenarios were developed to quantify the range of GPP losses associated with urban land transformation, estimating potential losses of up to 120 Gg C/year when urbanization occurs on the most productive vegetative land covers. We also show that impervious surfaces systematically increase surface runoff, particularly during autumn and winter in northern Mediterranean cities, where elevated rainfall may amplify flash-flood susceptibility. These results indicate that urbanization exerts a measurable and policy-relevant influence on Morocco’s surface energy, water and carbon budgets, underscoring the need to account for it in future development planning.