Mapping Decadal Soil Dynamics and Projecting Climate-Driven Degradation Impacts on Global Agricultural Yields: The HUMERIS Framework

Climate change and more frequent weather extremes are degrading soils faster than most land management frameworks anticipated. Rising temperatures and shifting rainfall disrupt the biochemical and physical processes that keep soils functional: accelerating organic matter loss, nutrient depletion, and salinization across regions that produce much of the world's food. This study tracks how soil properties have changed over the past four decades and estimates what those changes mean for crop yields, combining digital soil mapping, climate warming scenarios, and econometric production models. The first component builds on the HUMERIS framework, using Google Earth Engine and Random Forest algorithms to reconstruct annual dynamics (1985–2023) for organic carbon (OC), nitrogen (N), pH, and electrical conductivity (ECe). Historical trends diverge sharply by land use. High-latitude regions show climate-driven accumulation of OC and N. Areas converted from natural ecosystems to cropland show a consistent relative decline of roughly −0.2% per year in those properties. The pattern is clear: agricultural conversion erodes the soil properties that sustain long-term fertility. The second component projects forward. Applying HUMERIS under +2°C and +4°C warming scenarios from CMIP6, the model predicts substantial OC losses across mid-latitude regions and subpolar peatlands, where higher sustained temperatures accelerate organic matter decomposition. Salinization expands across arid and semi-arid zones (the Mediterranean Basin and Australia especially) as lower rainfall and stronger evapotranspiration drive salt accumulation in topsoil layers. To put numbers on the agricultural consequences, projected soil properties were fed into a Cobb-Douglas production function estimated for maize, wheat, rice, and soybean, controlling for labor, capital, fertilizer, and irrigation. The results indicate a production-weighted global yield decline of 1.0% under +2°C, rising non-linearly to 3.8% under +4°C. Most of the damage is concentrated in temperate mid-latitude systems, where the absolute loss of historical OC stocks is largest. Taken together, the findings suggest that climate change is not just warming the planet, it is quietly relocating its most productive agricultural land. This work provides a quantified link between soil degradation and yield loss that can inform where land protection and soil management investments are most urgent.