The other factors are these. Large-scale changes in Savanna vegetation cover are also major abiotic factors affecting the Savanna. This may reflect the drying trend in the regional rainfall patterns. Modeled removal of Savannas from global vegetation cover has larger effects on global precipitation than any other biome and, in four out of five savannas studied globally, modeled Savanna-grassland conversion resulted in 10% lower rainfall, suggesting positive feedback between human impacts and changing climate.